The Singapore Engineer September 2019 by The Singapore Engineer

THE MAGAZINE OF THE INSTITUTION OF ENGINEERS, SINGAPORE

THE SINGAPORE ENGINEER

September 2019 | MCI (P) 105/03/2019

COVER STORY: Creating a high-rise building with a sloping faรงade in a congested site

PLUS

HDB AWARDS: Projects honoured for excellence in design as well as in engineering and construction CONCRETE TECHNOLOGY: New concrete systems created by research PROJECT APPLICATION: Upgrading the Bisagno Stream in Genova for increased safety

www.ies.org.sg

I BUILD ON EXPERIENCE I see the possibilities my career can bring. Because a career in the built environment is one that can create direct yet far-reaching impact. At BCA, my work on policy measures help to drive change in the built environment sector and make a positive difference. We constantly shape the landscape to prepare for the future of Singapore, rally the built environment sector to achieve farreaching goals beyond today, and improve the living environment for Singaporeans from all walks of life. Be part of this transformation, and join us for a fun and meaningful career. Find out more about our career opportunities at www.bca.gov.sg

Lim Yong Xian Senior Engineer

CONTENTS FEATURES COVER STORY

16 Creating a high-rise building with a sloping faรงade in a congested site Frasers Tower was a Winner of the Design and Engineering Safety Award 2019 at BCA AWARDS 2019.

HDB AWARDS

26 Projects honoured for excellence in design as well as in engineering and construction A total of 27 awards were presented this year to architectural consultants, engineers and building contractors.

CONCRETE TECHNOLOGY

32 New concrete systems created by research Interesting results are obtained through the application of optimisation theory and machine learning, as well as concepts based on natural growth.

President Prof Yeoh Lean Weng Chief Editor T Bhaskaran t_b_n8@yahoo.com

Publications Manager Desmond Teo desmond@iesnet.org.sg Publications Executive Queek Jiayu jiayu@iesnet.org.sg

Editorial Panel Dr Chandra Segaran Prof Simon Yu Dr Ang Keng Been Dr Victor Sim Mr Syafiq Shahul Media Representative MultiNine Corporation Pte Ltd sales@multi9.com.sg

Design & layout by 2EZ Asia Pte Ltd Cover designed by Irin Kuah Cover images by Meinhardt (Singapore) Pte Ltd Published by The Institution of Engineers, Singapore 70 Bukit Tinggi Road, Singapore 289758 Tel: 6469 5000 I Fax: 6467 1108 Printed in Singapore

THE SINGAPORE ENGINEER September 2019

www.ies.org.sg

PROJECT APPLICATION

39 Upgrading the Bisagno Stream in Genova for increased safety A section of the bed of the waterway in Italy was widened and reinforcement rods were protected against corrosion. 42 Formwork solution for a subway station in San Francisco When completed, the Chinatown Subway Station will form the northern end of San Francisco’s Central Subway System.

43 A trio of cranes deployed in Paris metro station project Special foundation work for the future KremlinBicêtre Hospital metro station is nearing completion. 44 Building the world’s longest and deepest subsea road tunnel It is part of the reconstruction of the Coastal Highway Route E39 in Norway.

42 REGULAR SECTIONS 04 INDUSTRY NEWS 10 EVENTS 45 IES UPDATE

The Singapore Engineer is published monthly by The Institution of Engineers, Singapore (IES). The publication is distributed free-of-charge to IES members and affiliates. Views expressed in this publication do not necessarily reflect those of the Editor or IES. All rights reserved. No part of this magazine shall be reproduced, mechanically or electronically, without the prior consent of IES. Whilst every care is taken to ensure accuracy of the content at press time, IES will not be liable for any discrepancies. Unsolicited contributions are welcome but their inclusion in the magazine is at the discretion of the Editor.

THE SINGAPORE ENGINEER September 2019

INDUSTRY NEWS

Regenerating the old and using technology

to help deliver a sustainable future More than 600 real estate decision-makers and technology trail-blazers came together recently for the Urban Land Institute’s (ULI) 2019 ULI Asia Pacific Summit, and discussed ways of delivering a sustainable future. Held in Shanghai, China, over three days, the summit highlighted how technology can change the way urban spaces are developed, how data is driving businesses to adapt to new trends, the importance of urban regeneration and the business case for healthy buildings. Dr Wang Jian, Chairman of Technology Steering Committee, Alibaba Group, delivered this year’s keyone address on ‘Technology and Humanity - What is the Future?’ His talk covered how technology can be used to merge the human and digital worlds. Dr Wang outlined how Alibaba’s City Brain is solving traffic congestion in Hangzhou and encouraged the audience to be unafraid of new technology, noting that when electricity was first introduced, people were scared of it. Making real estate sustainable is not an optional extra for businesses that want to improve their bottom line, declared a panel of distinguished developers. Panellists discussing the topic ‘Delivering a Sustainable Future - the Impact of Real Estate’ included David Warneford, Managing Director, Hines, Australia, who said that the reality in the modern era is that “You cannot be commercially successful unless you are sustainable”. Boston Properties CEO Owen Thomas noted sustainability is not just a matter of energy use, but encompasses social and governance factors, too. At the ULI Members Luncheon, leading Chinese developers mentioned that although they are concerned about the effects of the US-China trade dispute, they still believe that growth in domestic consumption will support local real estate markets. The session included Feng Lin, Chief Executive, CIFI Group; Angela Zhao, Co-President, Real Estate, GLP China; and Ding Liye, Senior Vice President, China Vanke and CEO, SPCG Group. Real estate is famously technophobic, but the data era is now driving businesses to adapt to new trends, such as wellness, flexibility and meeting the aspirations of millennials. Developers, designers, futurists and millennials were all represented on the panel titled ‘The Evolution of a Dinosaur: Real Estate and the Future of Work’, co-hosted by Phil Kim, Managing Director Asia Pacific, Jerde Partnership, and Bill Lee, Senior Director, PropTech Investments and Real Estate Development, Gaw Capital Partners. Mr Lee said that data is the foundation for evolving real estate, allowing developers to build in flexibility and retail landlords to track shoppers. 04

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The 2019 ULI Asia Pacific Summit was held in Shanghai, China.

Shanghai has large numbers of heritage properties around the city, which are being conserved in a variety of ways. The ‘Shaping Neighbourhoods through Urban Regeneration’ session looked at several innovative regenerations of Shanghai buildings and neighbourhoods. “Shanghai has multiple historic resources”, said Filippo Gabbiani, Founder and Principal Architect, Kokaistudios, which took a derelict building in the French Concession and transformed it into a luxury retail destination that is now also home to the exclusive Kee Club. The case for healthy buildings is clear to the experts who took part in the ‘Healthy Buildings - Not in the Eye of the Beholder’ session, although they concede that investors and tenants need more convincing. The thesis is pretty straightforward, explained Billy Grayson, Executive Director, ULI’s Centre for Sustainability and Economic Performance. Staff costs account for 90% of a tenant’s expenses, compared with 1% for energy and 9% for rent and operating costs. Therefore, a small increase in staff productivity is like getting all your energy for free, said Bob Pratt, Global Co-Head and Managing Director, Design and Construction, Tishman Speyer. The ULI Asia Pacific Awards for Excellence were relaunched this year. Applicants from 50 projects competed across a range of criteria including design, planning, construction, sustainability, replicability and positive impact on their communities. Ten award winners were chosen by an expert jury from across the region, with three winners picked from mainland China. Day 3 saw a selection of study tours that explored how people live, work and shop in today’s Shanghai.

INDUSTRY NEWS

SBS Transit, SMRT, and ST Engineering sign MOU on improving railway engineering competence To foster greater knowledge-sharing and grow local rail maintenance and engineering capabilities, SBS Transit (SBST), SMRT Trains, and ST Engineering signed a Memorandum of Understanding (MOU) on 17 June 2019. Under the MOU, the parties will share engineering knowledge and capabilities in various areas with each other to add depth and breadth to their maintenance and engineering expertise. One of the areas for collaboration is in electronic cards as they are critical components of the MRT trains and signalling systems. To reduce the incidences of faults and decrease the down-time for repair work, local companies need to have deep understanding and maintenance expertise of the various systems, noted ST Engineering in their press release. The MOU will facilitate efforts to improve local capabilities in electronic card repair and diagnostic support, which will in turn contribute to better rail reliability. As

part of the three-year agreement, the three companies are free to explore other areas for collaboration. Mr Leong Yim Sing, SBST’s Head of Rail, said, “This MOU will further deepen our capabilities in rail engineering and maintenance as well as allow us to leverage on each other’s strengths and experiences to develop innovative solutions to improve rail reliability and performance.” “This MOU underscores SMRT’s intent to further strengthen our engineering capabilities and improve our rail reliability. This collaboration will enable us to synergise the expertise, resources and new technologies of our partners in a cost-effective manner,” added SMRT Trains CEO Lee Ling Wee. The MOU was signed by Mr Leong Yim Sing, Senior Vice President, Head of Rail, SBST; Mr Lee Ling Wee, CEO, SMRT Trains; Mr Tan Peng Kuan, President, Commercial Business, Land Systems, ST Engineering and Mr Yong Thiam Chong, President (Mobility), Electronics, ST Engineering.

Schneider Electric partners with Solar Impulse Foundation to speed up implementation of sustainable solutions French energy group Schneider Electric, through its Foundation, has entered into a four-year partnership with the Solar Impulse Foundation to select 1,000 solutions that protect the environment in a profitable way and awarding them the Solar Impulse Efficient Solution label. This label promotes solutions, assessed by independent experts, which combine technical innovation, profitability and environmental protection, demonstrating that solutions to fight climate change do exist and should not be regarded as expensive fixes but tremendous opportunities for clean growth. “By contributing to this project through the Schneider Electric Foundation, we want to push our employees to develop new solutions and implement the available ones,” stated Jean-Pascal Tricoire, Chairman and CEO of Schneider Electric and President of the Schneider Electric Foundation. To date, 179 solutions have already been selected, including biodegradable packaging made from milk protein, a solarpowered water purification plant, an enzyme-based plastic recycling technology and a zero-waste construction process.

The Solar Impulse Efficient Solution label is awarded to solutions after an anonymous assessment of a six-part application file, including an evaluation of their lifecycle Bertrand Piccard, Chairman of the Solar Impulse (in terms of Foundation (left), and Jean-Pascal Tricoire, carbon emissions, Chairman and CEO of Schneider Electric and recyclability, and President of the Schneider Electric Foundation. so on), business Photo: Schneider Electric model and the target country for implementation.

These will be promoted to corporate and political leaders worldwide through the Solar Impulse Foundation.

Through this partnership, Schneider Electric will help promote viable solutions that can achieve at least five of the 17 United Nations Sustainable Development Goals – clean, accessible water for all; affordable and clean energy; industry, innovation and infrastructure; sustainable cities and communities; and responsible consumption and production.

“Together, we will make every effort to accelerate the selection of profitable solutions that can protect the environment and work towards their large-scale deployment,” said Bertrand Piccard, Chairman of the Solar Impulse Foundation.

The Schneider Electric Foundation will promote the project within the group to mobilise experts to help with assessments, and has already set up a steering committee to select group solutions that protect the environment and enable access to electricity.

THE SINGAPORE ENGINEER September 2019

INDUSTRY NEWS

Singapore ratifies

international convention on WSH On 12 June 2019, Minister for Manpower Josephine Teo announced that Singapore had ratified the International Labour Organization’s (ILO) Occupational Safety and Health (OSH) Convention, also known as C155. The announcement was made at the centenary session of the International Labour Conference, which took place in Geneva, Switzerland. C155 is a key OSH Convention that requires ratifying countries to formulate, implement and periodically review a coherent national policy on OSH, in consultation with employers and workers. Singapore is the second ASEAN country to ratify this Convention, after Vietnam.

The conference delegation from Singapore included NTUC president Mary Liew and secretary-general Ng Chee Meng, SNEF president Dr Robert Yap, union members, employer representatives and officials from the Ministry of Manpower. This year’s Conference centred on the Report of the ILO’s Global Commission on the Future of Work, entitled “Work for a brighter future”. Singapore recently launched its Workplace Safety and Health (WSH) 2028 strategies to make its workplaces among the safest and healthiest in the world. The target is to reduce the workplace fatality rate from the current average of 1.4 per 100,000 over the past three years, to less than 1 by 2028, on a sustained basis.

THE SINGAPORE ENGINEER September 2019

INDUSTRY NEWS

Autonomous, self-docking boats bring new purpose to Amsterdam’s canals The city of Amsterdam envisions a future where fleets of autonomous boats cruise its many canals to transport goods and people, collect trash, or self-assemble into floating stages and bridges. To further that vision, MIT researchers have given new capabilities to their fleet of robotic boats that lets them target and clasp onto each other, and keep trying if they fail. The “Roboat” project, as it is called, is developed in collaboration with the Amsterdam Institute for Advanced Metropolitan Solutions. The idea is to build a fleet of autonomous robotic boats, equipped with sensors, thrusters, microcontrollers, GPS modules, cameras, and other hardware, that provides intelligent mobility on water to relieve congestion in the city’s busy streets. Apart from providing on-demand transportation on waterways, it is envisioned that the roboat units can be used to automatically form “pop-up” structures, such as foot bridges and performance stages. The structures could then automatically disassemble at set times and reform into target structures for different activities. Additionally, the roboat units could be used as agile sensors to gather data on the city’s infrastructure, and air and water quality. “In Amsterdam, canals were once used for transportation and other things the roads are now used for. Roads near canals are now very congested and have noise and pollution, so the city wants to add more functionality back to the canals,” said first author Mr Luis Mateos, a graduate student in the Department of Urban Studies and Planning (DUSP) and a researcher in the MIT Senseable City Lab.

The socket component is a wide funnel that guides the ball component into a receptor. Inside the funnel, a laser beam acts like a security system that detects when the ball crosses into the receptor. That activates a mechanism with three arms that closes around and captures the ball, while also sending a feedback signal to both roboats that the connection is complete. Each docking station, typically a fixed roboat, has a sheet of paper imprinted with an augmented reality tag, called an AprilTag, which resembles a simplified QR code. Commonly used for robotic applications, AprilTags enable robots to detect and compute their precise 3D position and orientation relative to the tag. When a traveling roboat is roughly one or two metres away from the stationary AprilTag, the roboat calculates its position and orientation to the tag. Using that information, the roboat steers itself toward it and by keeping the camera and tag perfectly aligned, the roboat is able to precisely connect. The researchers are now designing roboat units roughly four times the size of the current models, which are more stable in the water. Further upgrades in the pipeline include tentacle-like rubber grippers that tighten around the socket pin, which can give the roboat units more control in situations such as towing platforms or other units through narrow canals, and a system that displays the AprilTags on a monitor to enable commands to be issued to multiple units to assemble in a given order.

In a paper presented at the International Conference on Robotics and Automation, the researchers describe roboat units that are able to identify and connect to docking stations. Control algorithms guide the roboats to the target, where they automatically connect to a customised latching mechanism with millimetre precision. If the connection is missed, the roboat will back up and try again. The researchers tested the latching technique in a swimming pool at MIT and in the Charles River, where waters are rougher. In both instances, the roboat units were usually able to successfully connect in about 10 seconds, starting from around 1 metre away, or succeeded after a few failed attempts. Each roboat is equipped with latching mechanisms, including ball and socket components, on its front, back, and sides. The ball component resembles a badminton shuttlecock — a cone-shaped, rubber body with a metal ball at the end. 08

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MIT researchers have given their fleet of autonomous “roboats” the ability to automatically target and clasp onto each other — and keep trying if they fail. The roboats are being designed to transport people, collect trash, and self-assemble into floating structures in the canals of Amsterdam. Photo: MIT

INDUSTRY NEWS

New office set up to grow

tech sector in Singapore The Economic Development Board (EDB), Enterprise Singapore (ESG) and Infocomm Media Development Authority (IMDA) have joined forces to support and capitalise on growth opportunities for Singapore’s technology sector with the establishment of Digital Industry Singapore (DISG). Staffed by 45 existing officers from the three statutory boards, DISG “will transform the way the Singapore government engages with the technology sector” as a single interface for the industry. Noting that Singapore was home to 80 of the top 100 global technology companies, and more than 4,000 home-grown and international start-ups, DISG Chief Digital Industry Officer Kiren Kumar said that his office would tap on the resources of its parent boards to establish Singapore as a global-Asia tech hub, from which new products, services, business models and partnerships will spring forth. On the consumer technology front, DISG will assist companies to tap into the growing, mobile-first Asian market to capture opportunities in areas such as ride-hailing, ecommerce, fintech and new media. In the enterprise technology segment, DISG will leverage Singapore’s established base of diverse industry sectors

and ongoing investments to digitalise the economy to help companies build new solutions in areas such as cybersecurity, artificial intelligence, payments and cloud solutions that can scale globally. The office will also work with industry and relevant government agencies to create policies that will guide investments in areas such as data, talent, trade and digital infrastructure. This enhances Singapore’s capabilities and competitiveness. These efforts are expected to create up to 10,000 new jobs within the technology sector over the next three years. Beyond roles in engineering, software and product development, DISG expects that jobs in other functions, such as finance, human resources, innovation and business development, will also be created. To prepare Singaporeans for these frontier jobs, DISG will work closely with IMDA, the industry and local education institutions to implement training programmes and onthe-job training. These will cover areas such as artificial intelligence, cybersecurity, data science, network engineering, software development, user experience design and product management.

New Chair for ULI Singapore Ms Ong Choon Fah, CEO and Head, Research & Consulting at Edmund Tie & Company, has been appointed Chair of Singapore for the Urban Land Institute (ULI), an interdisciplinary research and education institute with more than 43,000 members dedicated to leadership in real estate and land use and creating thriving communities worldwide. Ms Ong has more than 25 years of experience in real estate and Ms Ong Choon Fah academia spanning various sectors, with public and private sector clients, for-profit and non-profit organisations, occupiers, investors, institutions and REITs. She succeeds Mr Khoo Teng Chye, Executive Director for the Centre for Liveable Cities (CLC), Ministry of National Development (MND), who held the position of ULI Singapore Chairman for two years, and who, as ULI’s first regional Council Chair to come from the public sector, greatly enhanced the engagement between the public and private sectors.

Stepping into her new position, Ms Ong plans to focus her efforts on the following: • Expanding ULI’s Advisory Services Programme by introducing Technical Assistance Panels (TAPs) to Singapore. TAPs are part of the ULI Advisory Programme formed to address land use challenges that require local knowledge to resolve. • Forming another Product Council - a specific group of ULI members, that will meet regularly and exchange information and share best practice around a particular issue related to the responsible use of land. • Building up ULI’s NEXT Member Network in Singapore. NEXT is a specific ULI programme that engages and supports ULI members aged 35 to 45 in all of ULI’s activities. NEXT supports the ULI mission by identifying, connecting, and elevating the next generation of leaders for the built environment and ULI globally. “It is an honour for me to be invited to be Chair of ULI Singapore, building on the outstanding work that Teng Chye has done. I obviously want to cater to the needs of ULI’s existing members but I also want to further promote the great work that ULI is doing in Singapore and to work with both the public and educational sectors in helping to extend ULI’s mission in the market”, said Ms Ong.

THE SINGAPORE ENGINEER September 2019

EVENTS

Intelligent Transport Systems World Congress

to be held in Singapore

The venue for the 26th ITS World Congress. Image by Suntec Singapore Convention and Exhibition Centre.

The 26th Intelligent Transport Systems World Congress (ITS World Congress) will be held from 21 to 25 October 2019 at Suntec Singapore Convention and Exhibition Centre. This is the first time that the anuual event is being hosted in Singapore. Addressing the theme ‘Smart Mobility, Empowering Cities’, the 26th ITS World Congress will bring together the latest global technology, innovation and talent, thereby creating unique opportunities to enhance the transportation experience across the world today and in the future. Organised by Singapore’s Land Transport Authority (LTA) and the Intelligent Transportation Society Singapore (ITS Singapore), in collaboration with ITS Asia-Pacific, ITS America and ERTICO - ITS Europe, this year’s edition of the event will address pertinent industry topics such as automated vehicles, multimodal transport of people and goods, big data analytics, innovative pricing and travel demand management, as well as cybersecurity and data privacy. Delegates and participants can look forward to a robust line-up of technology demonstrations, technical tours, a high-level policy round-table, plenary and congress sessions, and a strong line-up of exhibitors at the congress, whilst also discovering what Singapore has to offer as a leader in the field of intelligent transportation systems. The event is expected to host, over the five days, more than 300 exhibitors, 10,000 participants and 20 technical tours and demonstrations. 10

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Technical programme themes The 2019 congress aims to deliver a comprehensive fiveday programme centred around eight broad themes: • Intelligent, Connected & Automated Vehicles • Crowdsourcing & Big Data Analytics • Sustainable Smart Cities • Multimodal Transport of People & Goods • Safety for Drivers & Vulnerable Users • Policies, Standards & Harmonisation • Innovative Pricing & Travel Demand Management • Cybersecurity & Data Privacy More information on the event can be found on https:// itsworldcongress2019.com/.

EVENTS

Bentley Systems to host infrastructure leaders at the Year in Infrastructure 2019 Conference in Singapore

Bentley Systems’ Year in Infrastructure 2019 Conference will be held at Marina Bay Sands, Singapore. The structural design for Marina Bay Sands, by ARUP, was a Year in Infrastructure 2010 Award Winner for Innovation in Structural Engineering.

Bentley Systems, a leading global provider of software solutions and digital twin cloud services for advancing the design, construction, and operations of infrastructure will host its Year in Infrastructure 2019 Conference and Awards Ceremony at the Sands Expo and Convention Centre, Marina Bay Sands, Singapore. ‘Advancing BIM through Digital Twins’ is the theme of this year’s conference which takes place from 21 to 24 October 2019. The Year in Infrastructure Conference is an annual global gathering of leaders in infrastructure design, construction, and operations, to address best practices and technologies for going digital. This year’s conference features nearly 100 speakers and more than 150 informative sessions including keynotes by leading industry experts, user success stories, interactive workshops, panel discussions, and technology demonstrations. Dr Ayesha Khanna, Co-Founder and CEO of ADDO AI, an Artificial Intelligence (AI) advisory firm headquartered in Singapore, is one of the guest keynote speakers for this year’s conference. Dr Khanna has been a strategic advisor on Artificial Intelligence, Smart Cities and Fintech to clients including SMRT, SOMPO, and Smart Dubai. She was also named one of Southeast Asia’s ground-breaking female entrepreneurs, by Forbes magazine in 2018. Mr Keith Clarke, Chairman of the Board for UK-based Forum for the Future, is the other featured guest keynote speaker. Mr Clarke is a Chartered Architect with more than 40 years of experience in construction and engineering, and was formerly the Chief Executive of the global engineering and design consultancy firm, Atkins. He is a Non-Executive Director for Sirius Minerals plc, Chair of Future Cities Catapult and Tidal Lagoon Power plc, Vice President of the Institute of Civil Engineers, Patron of the Environmental Industries Commission at Oxford, and has honorary fellowships from the Royal Academy of Engineering, the Institution of Structural Engineers, and Cardiff University. He is also Visiting Professor for Sustainable Design at Aston University. 12

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Dr Ayesha Khanna, keynote speaker for the Year in Infrastructure 2019 Conference.

Mr Keith Clarke, keynote speaker for the Year in Infrastructure 2019 Conference.

Attendees will also hear from other industry thoughtleaders and learn about technologies and best practices that are shaping the future of infrastructure delivery and operations. Speakers from Bentley’s strategic partner organisations, including Microsoft, Siemens, and Topcon, will participate in technology demonstrations, presentations, and discussions on numerous topics. New to this year’s conference are ACCELERATE sessions led by Bentley’s application experts. Featuring more than 20 topics, the sessions provide insights into how organisations can master the latest enhancements and key capabilities of Bentley applications to help drive efficiency through multidiscipline workflows. Attendees can learn best practices through Academies Day sessions on digital advancement, construction, constructioneering, research, reality modelling, and process industries. The academies team will also conduct live, interactive sessions in the Technology Pavilion throughout the conference. In addition, the 2019 finalists in Bentley’s Year in Infrastructure Awards programme will present their projects during industry-focused forums which are on Buildings and Campuses, Digital Cities, Industrial Infrastructure, Rail and Transit, Roads and Bridges, and Energy and Water Utilities. Winners will be announced at an Awards Gala at the conclusion of the conference. Mr Chris Barron, Chief Communications Officer, Bentley Systems, said, “We are pleased to be hosting our Year in Infrastructure Conference and Awards Gala in Singapore again this year. Singapore is a leader in innovative use of technology for the delivery and operations of infrastructure and was named a Smart City in 2018, so it is a fitting and inspirational location to host an event that explores the innovations and best practices of technology use for outstanding infrastructure projects around the world”.

EVENTS

Singapore projects among the finalists for

the Year in Infrastructure 2019 Awards The annual awards programme honours the work of Bentley software users, in advancing infrastructure design, construction, and operations throughout the world. Twelve independent jury panels of distinguished industry experts selected 54 finalists from 571 nominations submitted by more than 440 organisations in more than 60 countries.

‘Tanjong Pagar Mixed-Use Development’ by ARUP Singapore Pte Ltd. Category: Geotechnical Engineering. Project Summary: Guoco Tower is a 64-storey, mixed-use development project in Tanjong Pagar, with an 18 m deep, three-level basement connected to the existing underground Mass Rapid Transit (MRT) railway station. ARUP Singapore was retained as the Civil & Structural consultant to develop a foundation design that met specifications impacting the MRT and surrounding city structures. Bentley applications facilitated accurate modelling, planning, and a timely, cost-effective foundation and earth retaining structural scheme that simplified and accelerated construction, while controlling impact on existing adjacent infrastructure sequence excavation works. Image by ARUP Singapore.

The Singapore projects named as finalists for Year in Infrastructure 2019 Awards are Tanjong Pagar Mixed-Use Development, Tuas Water Reclamation Plant, and Keppel Marina East Desalination Plant.

‘Tuas Water Reclamation Plant’ by PUB, Singapore’s National Water Agency, and Jacobs Engineering Group. Category: Water and Wastewater Treatment Plants. Project Summary: The Tuas Water Reclamation Plant is part of the Deep Tunnel Sewerage System Phase 2 project. The project team uses Bentley applications to create 3D models which ensure design consistency and improved multidiscipline coordination during the design and construction phases of the project. Image by Jacobs Engineering Group.

‘Keppel Marina East Desalination Plant’ by Keppel Infrastructure Holdings Pte Ltd and AECOM Singapore Pte Ltd. Category: Water and Wastewater Treatment Plants. Project Summary: Keppel Marina East Desalination Plant (KMEDP) is a large-scale, dual mode desalination plant that can treat either salt water from the sea or freshwater from the Marina Reservoir. Mostly underground, the facility features 20,000 m2 of parkland on the roof and an unconventional architectural design. The project team used Bentley applications to enable BIM strategies throughout design and construction. A digital twin of KMEDP is also under development. Image by AECOM Singapore. THE SINGAPORE ENGINEER September 2019

EVENTS

Demystifying Industry 4.0

adoption Industrial Transformation ASIA-PACIFIC 2019, a HANNOVER MESSE event, will be held from October 22 to 24 October 2019 at Singapore EXPO & MAX Atria. After its debut in 2018, the event returns this year with a focused and specialised approach to speed up Industry 4.0 (I4.0) adoption, with practical learning platforms and scalable solutions. “We have seen digitalisation, robotics and automation coming together to enable our customers to work side-by-side with technology and deliver new levels of productivity and safety. No matter the size of a company, digital transformation can help to realise new opportunities today to enable sustained business success while reducing the impact on environment and people. The challenge is no longer whether to start but how to scale and build momentum”, said Johan de Villiers, Country Managing Director, ABB Singapore. I4.0 adoption does not require organisations to overhaul existing machinery and equipment, when new software will work just as well. To meet the needs for I4.0 adoption, Industrial Transformation ASIA-PACIFIC 2019 will introduce the new Collaboration Lab, a platform for companies to collaborate and co-create by test-bedding and retrofitting solutions. Participating organisations include Singapore Polytechnic, Microsoft, Beckhoff, Rockwell Automation and Emerson. “In today’s complex digital economy, customisation is the norm. Companies that want to capitalise on the potential of I4.0 need to keep customer experience, front and centre. They can do this with a predictive and intelligent digital connected supply chain that connects the entire ecosystem of customers, suppliers, and partners. This integrated design to operate approach, from design, planning and manufacturing, to logistics and ongoing maintenance, allows businesses to design smarter, address issues with insight, and continuously innovate”, said Graham Conlon, Head of Digital Supply Chain, SAP Asia Pacific Japan. Furthering the agenda in smart logistics is the Learning Lab which features live demonstrations on the capabilities and applications of autonomous solutions in the intralogistics environment. The aim is to enable organisations to achieve flexibility, adaptability and proactivity in their processes. In the field of advanced manufacturing, one of the trends being observed closely by the industry is that of industrial robots, which have become smaller, smarter and more dexterous, making them a more attractive option. The Robotics Experiential Zone debuts this year to highlight robotics displays and interactive exhibits that emphasise their importance in advanced manufacturing and service sectors. Curated with Singapore Industrial Automation Association (SIAA), the zone will also highlight start-up pitches to uncover innovative solutions. To support these 14

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The inaugural edition of Industrial Transformation ASIA PACIFIC was held last year.

activities, SIAA will work with the National Robotics R&D Programme Office (NR2PO) to support IP generation in the robotics space. Industrial Transformation ASIA-PACIFIC 2019 will enable the following: • Planning for the future and influencing change from top down, with the CXO Summit for C-suite leadership and Future of Manufacturing workshops targeting midmanagement and practitioners. • Specialised learning with industry-focused tracks on energy, pharmaceutical & biotechnology, electronics & electrical, FMCG & F&B, aerospace, logistics & supply chain, chemical, infrastructure & facilities, urban solutions, and automotive. • Comprehensive and practical engagement with 120 guide tours covering 12 industry sectors across three days. • Targeted learning with 50 Sandbox sessions for beginners, early adopters and trailblazers. • Future-readiness via innovation adoption and problemsolving, with the CXO Summit, Global AM Summit, Standards Forum and specialised workshops. Organised by SingEx Exhibitions and international partner Deutsche Messe (organisers of HANNOVER MESSE), Industrial Transformation ASIA PACIFIC 2019 will present a self-contained ecosystem for end-to-end engagements among I4.0 practitioners, technology & solution providers, industrial companies, component manufacturers, software companies, manufacturing solutions suppliers, service companies & consultancies, and start-ups. More information on Industrial Transformation ASIAPACIFIC 2019, may be obtained from https://www. industrial-transformation.com.

EVENTS

IRENA and Siemens to deliver Opening Keynote Addresses at SIEW 2019 Two global energy leaders will deliver the Opening Keynote Addresses at Singapore International Energy Week 2019 (SIEW 2019) which will run from 29 October to 1 November 2019 at the Sands Expo and Convention Centre, Marina Bay Sands, Singapore. Francesco La Camera, Director General of the International Renewable Energy Agency (IRENA) and Cedrik Neike, Member of the Managing Board and Chief Executive Officer of Smart Infrastructure, Siemens AG, will share their perspectives on this year’s theme, ‘Accelerating Energy Transformation’. They will focus on the growing role of renewable energy and technology in transitioning to a sustainable energy future. Singapore’s Minister for Trade and Industry, Mr Chan Chun Sing will deliver the SIEW Opening Remarks. The Singapore Energy Summit this year will feature distinguished energy stakeholders discussing ways to accelerate energy transformation, fuel electrification, and digitalisation, and to create an enabling regulatory and financing infrastructure to facilitate this transition. Keynote speeches will be delivered by HE Armida Salsiah Alisjahbana, Executive Secretary, United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP) and HE Eng Awaidha Murshed Ali Al Marar, Chairman of the Abu Dhabi Department of Energy, United Arab Emirates.

• Amir Hamzah, President & CEO, Tenaga Nasional Berhad, Malaysia • Han Jun, Executive Vice President, State Grid Corporation of China • Kazuhiro Takeuchi, President & CEO, Japan Renewable Energy • Bernard Esselinckx, President & CEO, Senoko Energy • Shigeki Miwa, Representative Director & CEO, SB Energy Corp • Dr Dirk Biermann, Chief Markets and System Operation Officer, 50Hertz • Marianne Laigneau, Group Senior Executive President, EDF

Singapore International Energy Week Now in its 12th edition, the Singapore International Energy Week (SIEW) is a premier platform in Asia for energy insights, partnerships and dialogues, which brings together the world’s leading conferences, exhibitions and roundtables in one week and at one location. Organised by the Energy Market Authority (EMA), SIEW enriches the global energy conversation by convening political, business, academic and energy industry thought-leaders to define and advance the world’s leading energy challenges, solutions and actions across the energy spectrum of oil & gas, clean and renewable energy, and energy infrastructure financing.

More information on SIEW may be obtained from The energy policy makers and industry captains joining www.siew.sg. SIEW 2019 include: • Dr Koh Poh Koon, Senior Minister of State, Ministry of Trade & Industry, Singapore • HE Dato Seri Setia Dr Awang Haji Mat Suny Bin Haji Mohd Hussein, Minister of Energy, Manpower and Industry, Brunei Darussalam • HE Yeo Bee Yin, Minister of Energy, Science, Technology, Environment and Climate Change, Malaysia • HE Alfonso Cusi, Secretary of Energy, Philippines • Dato Lim Jock Hoi, Secretary General, ASEAN • Kurt Donnelly, Deputy Assistant Secretary, US Department of State • Tommy Joyce, Deputy Assistant Secretary, US Department of Energy • Dermot Nolan, CEO, Office of Gas and Electricity Markets (OFGEM), At last year’s edition of the event, IRENA signed a partnership with ASEAN to scale up deployment of United Kingdom renewables. THE SINGAPORE ENGINEER September 2019

COVER STORY

Creating a high-rise building with a sloping façade in a congested site Frasers Tower was a Winner of the Design and Engineering Safety Award 2019 at BCA AWARDS 2019. INTRODUCTION Frasers Tower is a commercial development comprising a 38-storey office building, a three-storey retail podium, and three basements essentially for carparking. The site, located at the junction of Cecil Street and Telok Ayer Street, was the site of the former Telok Ayer Performing Arts Centre. The total Site Area and Gross Floor Area (GFA) are 7,603 m2 and 77,162 m2, respectively. More than 90% of the GFA is designed as Grade-A office space while the remaining areas are essentially for restaurants and F&B outlets in the podium. There is also an underground pedestrian walkway (UPW) that provides direct connectivity from Basement 1 to the Tanjong Pagar MRT Station Underpass under Telok Ayer Street and the Telok Ayer Park.

• Very close proximity to Telok Ayer Chinese Methodist Church, a National Monument building and surrounding buildings like The Clift and Bangkok Bank Building. • Tight site and access constraints. • Having to perform construction activities in a dense city centre. Construction safety and risk management were key considerations during the design process.

The iconic 38-storey office tower is approximately 235m high. It offers a flexible work environment providing both indoor and outdoor work areas, with lots of green and sustainable spaces that will act as a stimulus for innovation and for transformation of work methods. The three-storey podium mainly houses the integrated F&B and retail outlets. Those who work in the building can also benefit from the chill-outs provided at ground level and from breakout spaces within the tower, for communal and recreational activities, whilst also enjoying stunning views of the city centre. The floor-to-floor height within the office tower is typically 4.8 m. Located within the Central Business District, the site is surrounded by many buildings, structures and services. These include the well-preserved Telok Ayer Chinese Methodist Church which is gazetted a National Monument, The Clift condominium and Bangkok Bank Building. The Frasers Tower project was tendered out under two contracts - the first for an advanced foundation package consisting of the installation of secant and bored piles, and the second package for the main building works.

STRUCTURAL DESIGN PROCESSES AND SOLUTIONS EMPHASISING SAFETY The main challenges in the design and construction of Frasers Tower were: • The creation of an iconic and slender high-rise tower with a sloping façade and columns. • Deep basement construction in highly variable Jurong Formation. • Construction of the underground pedestrian walkway below Telok Ayer Street to Tanjong Pagar MRT Station Underpass. 16

THE SINGAPORE ENGINEER September 2019

Frasers Tower

COVER STORY

Location plan

Frasers Tower - architectural expression and floor usage THE SINGAPORE ENGINEER September 2019

COVER STORY

Typical soil profile

Basement construction adopting semi-top-down method and ring slab plans

Secant pile layout for main basement

excavation. The general depth of excavation was approximately 12 m below ground. Over the tower footprint, the depth was about 14 m. The presence of the monumental building posed a huge challenge to the project. The church is a three-storey building which was built in 1925. There was no as-built information on the building, apart for information on some minor restoration work done in the 1990s. The church was very well preserved and in a good condition. As the nearest excavation was only about 3 m away, the Client was extremely concerned about safeguarding this important monument where many people congregated, every week.

Geotechnical model for ERSS analysis

Buildable ERSS system and robust excavation methodology for the main building A total of 22 boreholes were drilled to investigate the subsurface condition, with the deepest going 80 m into the ground under the tower. Investigation of soil properties at the site indicated that the site was underlain predominantly by the Jurong Formation. This formation is known to be highly variable and unpredictable. Top layers of fill and Kallang Formation material were encountered over the Jurong Formation across the site. The Kallang Formation consisted of a mixture of fluvial sand and fluvial clay. These loose or soft layers were generally found to be thin and within the depth of the basement 18

THE SINGAPORE ENGINEER September 2019

A robust, and yet practical, semi-top-down method was adopted. A secant pile wall, comprising a hybrid of 1000 mm dia and 1200 mm dia hard piles with 600 mm dia soft piles, was installed along the basement perimeter. The 1200 mm dia secant piles were installed for the wall adjacent to the church to provide higher wall stiffness to reduce deflection during excavation. The 1st storey and basement slabs were designed as rings to strut the wall during excavation. In addition, the 1st storey was also checked and detailed to support construction and traffic loads. King posts were installed in the bored piles to support the slabs during the temporary condition. Secant piles were preferred over a diaphragm wall as it is more suitable for installation in Jurong Formation which can be as hard as S(III) in some parts of the site. A skin wall was cast against the secant pile wall to prevent water ingress in the permanent condition. A careful review of the adjacent as-built structures revealed that the corewall of The Clift condominium was supported on a piled raft. The building was right next

COVER STORY

Basement excavation and tower corewall construction

to the excavation. An assessment of the actual bearing pressure on the ground from the raft, and cross verification with the allowable bearing pressure on the as-built drawing, were carried out. In carrying out the basement excavation analysis, the estimated bearing pressure of 390 kPa from The Clift was input as a surcharge. The ERSS (Earth Retaining and Stabilising Structure) wall and slabs were designed for the resulting forces. Predicted wall deflections and ground movements were also checked to ensure these were within specified limits. Allowable wall deflections were generally kept to within 0.5% of the excavation depth. The strut-free basement excavation enabled efficient removal of earth in a safe and tidy working environment. The design and execution of the work were also carried out effectively, with the final wall deflections and ground movements kept within the specified limits. The basement construction was successfully completed with no adverse impact on the church, The Clift and Bangkok Bank building.

Hybrid raft foundation with settlement-reducing piles From the soil investigation carried out, the B3 formation level was generally located within the weathered rock of the Jurong Formation, except for a localised area under the tower where it was still Residual Soil S(VI). The feasibility of adopting a raft foundation was carefully studied and investigated during the concept stage. While it was concluded that a raft foundation was viable for the podium, a hybrid raft foundation with settlement reducing piles was adopted for the high-rise tower, due to its much higher columns and corewall loadings. The tower and podium raft thicknesses were 1.3 m and 3.5 m, respectively. Piles were provided under the heavily-loaded tower core where there was high stress concentration and under the tower columns to share the load with the raft. Single piles, with diameters from 1.8 m to 2.2 m, were provided below the tower columns. During demolition of the existing buildings, the existing piles were exposed and their positions surveyed. These were overlaid with the new pile positions to ensure there was no clashing during installation. Where there was the possibility of the new piles being obstructed, they were shifted to facilitate installation.

Raft foundation with settlement-reducing piles

Sensitivity studies were undertaken to assess the distribution of the tower loads between the raft and piles to arrive at a balanced and cost-effective design, with acceptable overall settlement and angular distortion to the building. The geotechnical models used in the analysis were also correlated and calibrated against the test results and findings from the ultimate and working pile load tests for a more accurate determination of the behaviour. Final distribution of the load between raft and piles was approximately 45% to 55%. Tension piles were provided for the podium raft to resist the permanent water pressure uplift. The differential movements between the tower and podium rafts were also checked to ensure compatibility and that they were not excessive. The maximum differential settlement was calculated to be 1 in 750, which is within the general allowable limit of 1 in 500. The bending moments and shear forces at the interface were also designed for the anticipated rotation between the slabs to ensure structural adequacy and to avoid excessive in-service cracking.

Buildable substructure and superstructure structural systems Two primary structural systems were essentially adopted for the project, where applicable, due to the different THE SINGAPORE ENGINEER September 2019

COVER STORY

configurations of the basements, podium and tower. These were flat plate and band beam systems. Both systems are highly buildable and have their own advantages and applications. The flat plate system was adopted for the basements as this can better facilitate top-down construction and simplifies excavation and construction. The flat plate system was also used for the podium floors, offering higher ceiling height for the retail and F&B spaces. The band beam system was generally adopted for the tower footprint due to the requirement of column-free spaces between the core and the building edge. This was carried through from B3 all the way to the tower roof. The office tower is divided into three zones namely, low, mid and high zones, which are dictated by the provision of vertical transportation to serve these zones. The typical floor plate comprises a central core with only perimeter columns, offering interior column-free office spaces on every floor. The core to window depth varies from 15 m to 16.5 m. A post-tensioned band beam system was adopted for the typical office floors. The one-way slabs were post-tensioned, and in turn supported by the post-tensioned beams spanning from the perimeter columns to the core. This system is most efficient for Grade A office layout, as it offers long span, column-free spaces. It facilitates the use of table forms that can be standardised and made repetitive for the tower construction. Construction was also made simpler and more buildable by curtailing the post-tensioned tendons outside the corewall to simplify tendon installation, so that the core can climb independently and ahead of the floor slabs. These were compensated by non-tensioned rebars that can be readily anchored into the corewall using couplers or bent bars. Once momentum of the superstructure construction picked up, the Builder was able to achieve a seven-day floor cycle for the construction of a typical tower floor.

Innovative load transfer mechanism The design of high-rise buildings, taking into consideration gravity and lateral loads, and ensuring overall building stability and performance, presents a considerable challenge. One of the iconic features of the Frasers Tower development is the sloping façades on the two long sides of the tower, facing Cecil Street and Telok Ayer Street. The façade slopes outwards at an inclination of 5º from the 1st to the 9th storey and then changes to slope inwards at an inclination of 0.8º up to the roof. In order to maximise the column-free spaces within the offices, the proposal from the design engineers was to slope the columns to align them with the façade inclination, instead of keeping the columns straight throughout, and providing short cantilevers to support the building edge. The inclination of the tower columns (12, in total) posed additional challenges in both the design and construction. With sloping columns, the design process becomes much more complex, as secondary lateral forces will be induced onto the floor slabs (in-plane), which would not have happened if the columns are vertical.

THE SINGAPORE ENGINEER September 2019

Column inclination and global load path assignment

Sloping columns would induce horizontal forces in the floor slabs at every floor. These forces would either be in compression or tension, depending on the direction of slope. The magnitude of the force would depend on the column inclination and the vertical load on that floor. The critical locations would actually be at the floors where the columns change their inclination. This happens at the 1st and 9th storeys, resulting in large horizontal in-plane forces on these two floors. The 9th storey slab is subjected to tensile forces and the 1st storey slab to compressive forces. The strut-tie model was used to establish the horizontal forces in the floor slabs. Where the slabs are subject to compression, the concrete slab was checked for the additional stresses and designed accordingly. Where the slab was subject to tensile forces, these were post-tensioned to balance the tensile forces so that there is no residual tensile stress in the floor slab. It was necessary to do so, otherwise the contribution of the shear capacity of the concrete slab would have to be discounted totally. The horizontal forces in the floor slabs were transferred to and resisted globally by the core walls. The floor slabs were designed and detailed as horizontal deep beams, using the strut-tie model to effect the load distribution. The 8th and 10th storeys were also checked for secondary effects as the structural model indicated part of the horizontal force at 9th storey were distributed to these two floors due to compatibility. The building was relatively stiffer in the Y-direction compared to the X-direction, due to the length of the core. In order to enhance the building’s lateral stiffness in the X-direction and to avoid torsional behaviour of the structure under the 1st two modes, outrigger and belt beams were introduced within the MEP floors, at the 17th and 37th storeys, respectively. These outrigger beams engage and couple the core walls with the perimeter columns on both sides of the building to provide a larger lever arm effect in resisting the lateral loads. The belt beams along the building edges serve to distribute the resulting axial loads

COVER STORY

Roof crown structure

3D structural model

Superstructure construction

to the columns, rather than concentrating them onto just the four columns with which the beams are engaged. A 3-D structural model was created to undertake global analysis, design and assessment of building performance. The time periods and mode shapes were investigated and fine-tuned to comply with design codes and standards. As the building is more than 200 m tall and with a time period of approximately 7 s under its 1st mode, a wind tunnel test was carried out to verify the structural loads on the building and faรงade due to wind pressures. The wind forces from a 50-year-return wind speed were compared with the notional loads. The larger of the lateral loads was used in the design of the building structure, together with the application of gravity loads based on the various load combinations. The building accelerations at the top of the building were also evaluated from the wind tunnel test, based on a wind speed with a return period of 10 years, to ensure these are within the acceptable limits for office usage. Overall building and inter-storey drifts were also computed and checked to ensure these are within the allowable height/500. The simple solutions implemented to transfer both gravity and lateral loads via a hybrid of slabs designed adopting the classic strut-tie model, and outrigger and belt beams, are distinct and unique. This enabled a safe and buildable design and, at the same time, achieved the functional requirements and iconic design features specified by the Client and Architect, respectively.

Integrated roof crown design The roof crown is an important architectural element and expression of the tower. The crown encompasses the sky garden at the roof top and allows people to view and appreciate the skyline beyond. At night, it turns into an iconic lantern when viewed from the outside. The requirement was therefore to have a very light structure to support the faรงade. The height of the crown was approximately 38 m. A simple steel frame structure was proposed. The frame structure adopts structural tubes as the primary and secondary ele-

ments, which are integrated with the faรงade elements. These were designed to support the faรงade loads, maintenance access, as well as the wind loads. The wind forces at over 200 m were high. To provide lateral restraint, the frame structure was tied and braced back to the corewall. Lateral forces were also transferred to the corewall through these bracings. The steel frames were mainly fabricated off-site and lifted into position. Bolted connections were adopted where feasible to enhance site buildability. The end result was an elegant roof crown structure that offers stunning views from within and achieves the iconic appearance of the tower when viewed externally.

Underground pedestrian walkway One of the key challenges of the project is the construction of the underground pedestrian walkway (UPW) that connects the basement B1 to the existing Tanjong Pagar MRT Station Underpass. The UPW had to be constructed below the busy Telok Ayer Street, with minimal inconvenience and interference to pedestrian and traffic flows at all times. The UPW is essentially a reinforced concrete box structure. The width and length of the walkway are about 6 m and 100 m, respectively. The depth of excavation varied approximately, from 6 m to 8 m. 600 mm dia hard and soft secant piles were adopted as the ERSS retaining wall on both sides of the box. The secant piles were designed to provide lateral support to the excavation under both temporary and permanent conditions. The secant piles were also designed to penetrate adequately into the Jurong Formation as foundation piles to support the box structure. A RC skin wall was cast against the secant piles as a finishing wall and barrier against water ingress in the permanent condition. The top-down method was used to construct the UPW. This was adopted as it was a more robust solution that offered a safer working environment with the least impact on ground movements, particularly next to the MRT structures. Apart from limiting the MRT structure to an allowable movement of 15 mm, the allowable wall deflections for the other sections were similarly kept to 0.5% of the excavation depth. There were major services running beneath and across the road. These were carefully mapped out and were mostly suspended during excavation. Staged diversion of vehicular traffic was carried out to install the secant piles and the THE SINGAPORE ENGINEER September 2019

COVER STORY

A strut-free ERSS system adopting the semi-top-down construction method was implemented, in due consideration to the site constraints and challenges of the project. The close proximity of excavation work to the Telok Ayer Chinese Methodist Church (a National Monument), The Clift and Bangkok Bank Building required very stringent control on the wall deflections, associated ground movements and water table drawdown. By reinforcing the 1st storey slab to function as a strut to the wall as well as a temporary construction deck, the challenges of construction access and working spaces within a tight site were mitigated. The adopted robust ERSS scheme not only allowed excavation of the tower raft to proceed in a practical manner, but also enabled ground movements to be controlled effectively, thereby maintaining site and public safety. The design, detailing and specifications were documented to high standards in line with the design requirements and quality expectations. Working closely with the Builder and with an open mind, the specifications and requirements were implemented on site to ensure the basic functions, testing regime, code compliance and performance standards were met. The project was supervised on site with one Senior Resident Engineer, one Resident Engineer and three Resident Technical Officers. Underground pedestrian walkway under construction (above) and after completion (below)

excavation of tunnel. Close coordination with the Contractor and various Authorities were undertaken to ensure a smooth work progress on site. The MRT underpass was constructed with a designated knock-out panel, which made the connection of the UPW slightly simpler. An independent review of the MRT structure was undertaken to ensure there was no adverse impact to the structure after the removal of the knock-out panel. The position and size of the panel were also verified and confirmed on site, prior to removal. The removal of the panel was carried out using non-percussive methods, as in coring and diamond saw-cutting of the panel into smaller segments for disposal. The construction of the UPW was completed safely, with no adverse impact on neighbouring buildings, structures and services. There was also no adverse feedback of any inconvenience caused to the public during the construction work.

QUALITY APPROACH IN DESIGN, DETAILS AND SPECIFICATIONS A collaborative approach was adopted by the Consultant Team and Builder, in the design and construction, and accompanying specifications. Close design co-ordination and detailing ensured that there were no structural transfer elements, and safety considerations were incorporated into the design, from construction to maintenance. The site is located within the city centre at the junction of Cecil Street and Telok Ayer Street - an extremely busy vehicular and pedestrian node. Therefore, basement construction, material delivery as well as superstructure construction, required careful planning. 22

THE SINGAPORE ENGINEER September 2019

CONSTRUCTION QUALITY & SAFETY Completion of the basement excavation was the first major challenge in the project. The next was the construction of the superstructure within the remaining contract duration and in a safe manner, achieving the quality expectations of the project. The superstructure was designed adopting a post-tensioned band beam system for the typical floors. A specially-fabricated aluminum table form system was imported from Korea to undertake the floor construction. One of the benefits of the system was that it was lightweight, and could readily be managed and handled with lesser manpower. Besides enabling faster erection and dismantling, the accuracy of the formwork was observed to be better compared to conventional forms. System and self-climbing formwork was similarly used for the construction of the inclined columns and corewalls. The corewalls were generally cast a few levels ahead of the floor construction. The use of customised and good quality formwork enabled the in-situ construction to achieve a satisfactory quality finish, accuracy and standard. Thorough and comprehensive risk analysis studies were carried out regularly for every stage of the construction process to identify the key risk issues and to control and mitigate the preventive measures. A comprehensive instrumentation regime was put in place and monitored closely. Supervision of works was carried out progressively to ensure safety and quality, and to meet the progress targets set. Regular site meetings were held with the Builder to review and eliminate safety issues prior to the work activities. Inspection, testing and monitoring were carried out through quality checklists under Meinhardtâ&#x20AC;&#x2122;s ISO System Manual. The checklists are comprehensive guides which explain the roles and responsibilities of site staff, procedures for work inspections of all geotechnical and structural works, schedule and type of tests required,

COVER STORY

vation offered a safe working environment on site. Limiting and controlling wall deflections, ground movements and water drawdown to acceptable values further ensured that the challenging construction activities were completed without affecting the structural integrity of neighbouring buildings and services, particularly the Telok Ayer Chinese Methodist Church and MRT Station Underpass. The buildable structural systems adopted for the basements and superstructure not only improved productivity substantially, it also resulted in the generation of less wastage, less noise and less construction debris, as well as in a reduction in the risk from working at heights. The innovative design approach to create the iconic high-rise tower and the well-executed construction methods by the Builder, led to an overall safer and more productive working environment within the site. As a result, public safety surrounding the site was also well maintained. Inclined column construction

monitoring and recording instrumentation and test results, Quality Assurance / Quality Control (QA/QC) of the sources of materials and material testing results etc. Technical specifications were made available to the resident site team and detailed briefings were conducted to ensure full compliance with specifications and drawings. Approved shop drawings were circulated to all relevant parties prior to construction and inspection was allowed to be carried out based only on approved drawings. The resident site staff reported any deviation from approved shop drawings, and design changes due to site conditions were reviewed by the Qualified Person (QP), as well as by the Accredited Checker (AC), where required, prior to implementation. The QP and resident site team conducted regular site meetings / walks to ensure QA/QC.

DESIGN FOR SAFE INSPECTION AND MAINTENANCE The principles of Design for Safety were implemented despite their adoption not being mandatory at the start of the project. A risk assessment exercise was undertaken to ensure all anticipated risks were reviewed and addressed/ mitigated through design where practically possible. A critical consideration in the design was the ease of maintenance and replacement of M&E equipment and plant. The major M&E equipment and plant were located at the 17th and 37th storeys, respectively. The layouts were planned and coordinated to facilitate replacement of parts readily. Similarly, the maintenance of the building faรงade has always been a key consideration in any high-rise development. A clear decision was taken to provide a telescopic building maintenance unit above the core, which can swivel around the tower footprint to clean and maintain the faรงade. Despite the cost involved, it was a prudent decision to ensure the safety of the personnel cleaning the faรงade and also the safety of the inspectors conducting periodic inspections.

In conclusion, the project was successfully completed safely and on time, with no stop-work order, no public safety incident nor adverse feedback. The project achieved a high quality standard expected of a Grade A office building. PROJECT DATA Building Type Commercial Grade A Office Basement 3 levels carparking Podium 3 levels retail and F&B Site Area 7,603 m2 Gross Floor Area 77,172 m2 Building Height 235 m Connectivity Direct connection at B1 to Tanjong Pagar MRT Station Underpass Temporary Occupation Permit July 2018

PROJECT CREDITS Qualified Person Er. Kam Mun Wai C&S Consultant Meinhardt (Singapore) Pte Ltd Builder Hyundai Engineering & Construction Co Ltd Developer Frasers Property Singapore Architectural Consultant DP Architects Pte Ltd

PUBLIC SAFETY The adoption of a robust earth retention system and the semi-top-down method (strut free) during basement exca-

All images by Meinhardt (Singapore) Pte Ltd THE SINGAPORE ENGINEER September 2019

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Building & Research Meadow Spring @ Institute (HDB) Yishun LAUD Architects Pte Ltd

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ONG&ONG Pte Ltd

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THE SINGAPORE ENGINEER September 2019

Design & Build for Upgrading Projects - G19C

Project

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CONCRETE TECHNOLOGY

NEW CONCRETE SYSTEMS CREATED BY RESEARCH by Mark P Sarkisian, Partner, Skidmore, Owings & Merrill LLP, San Francisco, USA Research is essential for developing new ideas in concrete structures. Through creative use of materials, construction techniques and building performance, this research can address broad issues related to the life of structures, starting with urban planning and ending with health monitoring. Awareness is key to solving complex issues and the collaboration between academic study, research, and practice is critical. The article focuses on how research has manifested in new approaches to design. Examples will include the use of optimisation theory and machine learning, as well as concepts based on natural growth. Ideas will range from components in buildings to entire cities and the work shown will include projects from various places around the world. INTRODUCTION Recent research inspired by natural forms and supported by advanced analysis tools that utilise structural optimisation techniques has led to investigations of concrete systems that are both efficient and influential in creating new architecture. Historically, natural growth patterns have influenced art and useful products that use principles of assembly to create long-life, durable goods. The concept of interweaving structural elements is an appropriate approach to ideas on any scale - whether in constructing a basket or an ultra-tall building. Although optimisation analysis techniques have todate been largely used to understand behaviour rather than provide results that can be used for final designs, the process has been used to help define new structural system ideas for major tower structures. These structures tend to be highly customised with little repetition or mass application. Efforts recently have been made to develop ideas with greater application and use on structures of any scale. In addition, the process has led to even greater understanding of positioning of structural elements that not only respond to force flow but also to specific programmatic building requirements.

Figure 1: Natural plant formations.

Figure 2: Woven basket.

RATIONAL STRUCTURAL RESPONSE TO FORCE FLOW The competition submission for the China Merchants Bank Tower in Shenzhen, China, was influenced by natural force flow patterns and specific programmatic uses. A reinforced concrete frame was designed over the building height and responds directly to internal uses. Sketches of the structural system were refined during the process, finally resolving the structural solution with a frame that could be used in combination with a central reinforced concrete core interconnected with steel outrigger trusses or concrete walls to resist lateral loads imposed by wind and seismic conditions. These early sketches reflect a programmatic change approximately 3/4 of the height of the tower. 32

THE SINGAPORE ENGINEER September 2019

Figure 3: Organic frame concept.

CONCRETE TECHNOLOGY

Further refinement of the initial concept resulted in a structural system that: • Included a wider perimeter of reinforced concrete column spacing at the top of the tower where executive offices would include greater unobstructed views and flexible office spaces within. • Incorporated concrete frame transitions and primary joint public spaces approximately located at the 1 /4 and 3 / 4 height elevations in the tower, also corresponding to outrigger truss or wall interconnections with a central reinforced concrete core wall.

• Introduced closer perimeter reinforced concrete column spacing at the tower’s midsection where space would be leased and any structural premium for perimeter span eliminated. • Included a wider perimeter reinforced concrete frame at the lower portion of the tower to accommodate large, open, traditional floor spaces. Even though transitions of the frame were incorporated over the height of the tower, the system allows for continuous force flow without transfer of load. Gravity load in the perimeter frame offsets any potential uplift due to typhoon wind or moderate seismic demands.

GROWTH PATTERNS - CHENGDU TOWER COMPETITION

Figure 4: Optimisation analysis and potential lateral load-resisting frames.

A competition for a 600 m tall tower in Chengdu, China, created the opportunity to explore the use of natural growth patterns into a structure that combined structural steel and reinforced concrete in a creative solution. Initial concepts were developed around a stable tripod form where a reinforced concrete central core would resist torsional effects of wind and seismic loads, with the legs of the tripod resisting the combined effects of gravity and overturning forces. Further development of the structural system led to a design where segmented diagonal steel braces were introduced into the building perimeter and linked together at the segmented linear reinforced concrete walls at the perimeter. These links would also provide ductility during a seismic event, as they are designed to fuse under significant seismic demand.

Figure 5: Conceptual drawings of structural system for the China Merchants Bank Tower, Shenzhen, China.

The primary service elements, including express elevators, stairs, and mechanical spaces, were placed in the central core with local elevators placed at the outside of the tripod-shaped floor plan. The floors were typically column-free, with large reinforced concrete elements used at the perimeter to accept the bracing system.

Figure 6: Concrete frame elevation, programme description and final rendering of China Merchants Bank Tower. THE SINGAPORE ENGINEER September 2019

CONCRETE TECHNOLOGY

commercial and residential construction has been 0.9 psf to 1.0 psf. Attempts to reduce the amount of post-tensioning have not been successful even when considering banding and careful placement of material. However, research has shown that placing tendons on optimised load paths resulted in reductions of post-tensioning by 25% to 30%. Therefore, the quantity of post-tensioning required is now of the order of 0.65 psf to 0.75 psf. This reduction not only represents a reduction of raw material required, but also a reduction in construction time and carbon emitted into the atmosphere due to both the production and placement. Figure 7: Initial structural system concepts for Chengdu Tower, Chengdu, China.

Even though the 1111 Sunset Boulevard Project in Los Angeles incorporates an unusual core-only lateral system, the post-tensioned floor system is regular, utilising an optimised post-tensioning layout for tendons. The tendons are mapped based on analyses considering the vertical wall elements in plan. Repetitive, equally spaced columns result in a particularly good application of optimised post-tensioning for the slab framing. It should be noted that repetitive circular plan geometries emerge from this concept, that allow for easy markings on formwork for the layout of the tendons during construction. Since structural optimisation is based simply on the optimal placement of material, given particular loading and support conditions, the application to other design disciplines offers great opportunities. Urban planning, for

Figure 8: Chengdu Tower structural system description and typical floor plan.

Figure 10: 1111 Sunset Boulevard Towers, Los Angeles, USA.

Figure 9: Chengdu Tower rendering.

OPTIMISED SLAB SYSTEMS WITH OTHER POTENTIAL APPLICATIONS Post-tensioned slabs are commonly used worldwide in concrete structures on any scale. The slabs generally provide an efficient solution for long-span conditions with relatively thin slab thicknesses. Historically, the quantity of post-tensioning required to achieve usable spans in 34

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Figure 11: Optimised post-tensioning layout in plan for 1111 Sunset Boulevard Towers.

CONCRETE TECHNOLOGY

example, has similar design requirements such as density (load) which could be people or automobiles and areas where density should congregate (size of area where jobs are supported or where people live). Therefore, the horizontal structural slab (representing density) is considered a continuum supported by areas where density is congregated. When considering these conditions, optimal â&#x20AC;&#x2DC;loadâ&#x20AC;&#x2122; paths emerge. These paths could represent people or vehicular movements. The most efficient travel path is not necessarily a straight line between areas of congregated density. These less than expected paths could bring more efficient travel and less carbon emitted from this travel.

Figure 15: Optimised analysis considering urban planning density.

Figure 16: Interpretation of optimised analysis defining the most efficient paths of travel. Figure 12: Theoretical layout of completely symmetrical optimised post-tensioning, in plan, for 1111 Sunset Boulevard Towers.

DYNAMIC RESPONSES OF STRUCTURES - CREATIVE USE OF POST-TENSIONING All structures are in motion. Natural dynamic responses of structures are sources of inspiration for new structural systems. Free vibration of systems illustrates modal behaviour, and in seismic events, structural demands are directly related to site and superstructure characteristics.

Figure 13: Overlay of potential lines of post-tensioning over optimised slab analysis.

The use of post-tensioning in vertical structural elements will lead to better performance when subjected to seismic loadings. Reflecting on research performed for slab systems results in a geometric non-linear placement of post-tensioning. When placed in this manner for vertical column elements, the post-tensioning creates net compression on the members and also provides resistance to lateral loads applied in any direction. Post-tensioning could be placed three-dimensionally in columns subjected to biaxial bending. Similarly, geometric non-linear post-tensioning could be placed in frame beam members, to resist lateral cyclic loads applied in any direction. This placement of post-tensioning in both columns and beams acts to achieve essentially elastic behaviour in a seismic event and creates elastic strain energy in the overall system, that helps to establish re-centring after a significant seismic event.

MACHINE LEARNING AND THE FUTURE

Figure 14: Initial pass at post-tensioning layout (above) and the final interpretation of the layout (below).

Post-earthquake building damage identification One of the greatest economic losses associated with earthquake events is due to downtime for repair and rebuilding. Home owners and business owners of THE SINGAPORE ENGINEER September 2019

CONCRETE TECHNOLOGY

damaged buildings can wait months for an inspection to be completed by an expert. In some cases, they cannot occupy their homes or operate their businesses until this inspection is complete. Photo recognition technology can be employed to expedite this evaluation process and mitigate this lost time.

Figure 17: Structural dynamics - mode shapes.

A comprehensive and vetted machine-learning-based application could provide users with immediate feedback regarding the level of damage of their buildings - whether or not they can be occupied and whether or not they require major repairs. In addition, in the aftermath of a major earthquake, local and international reconnaissance teams upload hundreds of images to various databases, not all of which can be rapidly evaluated by experts. Integrating machine learning into these databases could make the photo cataloguing process not only more uniform and efficient, but also more comprehensive. Following the 7.1 magnitude Central Mexico earthquake on 19 September 2017, Skidmore, Owings & Merrill (SOM) sent a team of experts to Mexico City to contribute to post-disaster recovery efforts, by documenting building damage and providing technical support to local structural reconnaissance efforts. The preliminary observations from this reconnaissance mission are documented in Diaz et al (2017). In an effort to enhance post-earthquake reconnaissance capabilities, SOM performed tests using machine learning to identify and classify building damage, from the photos taken by the SOM reconnaissance team. Some results from these tests are shown in Figure 20.

Figure 18: Vertical post-tensioning in columns.

An object-detection-based machine learning model was trained, using approximately 40 annotated images in the training set. The model was trained to differentiate between the following eight classes: • nonstructural light damage • nostructural medium damage • nonstructural heavy damage • nonstructural severe damage • structural light damage • structural medium damage • structural heavy damage • structural severe damage

Figure 19: Post-tensioning in moment-resisting frames subjected to seismic loading. 36

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Figure 20: Examples of building damage identification and classification using machine learning.

The model was based on a Faster RCNN (Ren et al, 2015) approach using Resnet-101 (He et al, 2016). It was initialised with the pre-trained weights from the MS COCO dataset. One model was trained using 3,000 iterations, while another was trained using 10,000 iterations. The model trained to 10,000 iterations most likely overfit the data. This means that it very accurately represented the training data, at the expense of being as useful to novel data. Using a similar method with a training set of at least 1000 images may yield a model that generalises well to new data. Construction verification To advance efforts in applying machine learning to the construction industry, SOM and software developer Anthony Sarkis performed several proof-of-concept studies utilising photo recognition for construction verification. The intention of these studies was to provide an initial viability assessment of these applications, with minimal data gathering, annotation and computational effort. Therefore, small datasets, of the order of tens of images, were used to train the models. All models were trained using the Tensorflow Library (Abadi et al, 2016). Depending on the element in question, two different photo recognition techniques were employed - object detection and semantic segmentation. In object detection, a bouncing box is drawn around each class identified in the image. In semantic segmentation, every pixel in the image is associated with a class. A machine learning model was first trained to recognise rebars from site photos, using object detection, based on Faster RCNN (Ren et al, 2015) and Resnet-101 (He et al, 2016). The model was initialised with the pre-trained weights from the MS COCO dataset. However, as shown in Figure 21, the density of rebar is typically such that multiple, overlapping bounding box regions are identified in the photo, rendering the photo recognition results meaningless. SOM is also studying potential applications of AI in design. Using data from its WT 260 wind tunnel in Chicago, SOM is training a machine learning model to recognise

Figure 21: Rebar identification through object detection.

how different tall building shapes impact wind effects. Once tested and vetted, this tool could help designers quickly evaluate numerous massing options before testing a select few in the wind tunnel. The tool could also be used to propose new massing options and be combined with other models to optimise shapes for multiple parameters such as wind effects, solar energy and material quantities. To increase precision in the photo recognition results, a second machine learning model was trained, using semantic segmentation. Two different algorithms were used - an approach based on VGG 16 with skip connections and DeeLabV2 (Chen et al, 2016) with ResNet101. As shown in Figure 22, the second algorithm achieved significantly better results than the first, in terms of detecting the exact region of the main reinforcing bars (shown in the foreground of the images). THE SINGAPORE ENGINEER September 2019

CONCRETE TECHNOLOGY

Jury appointed for competition on sustainable design Figure 22: Rebar identification through semantic segmentation, using VGG 16 (the two images on the left), and using DeepLabV2 (the two images on the right).

CONCLUSIONS A great potential exists in the application of research to new concrete systems. Optimisation theory has created new opportunities in understanding force flows in structures. Geometric non-linear placement of material, such as post-tensioning, leads to optimised systems not only in structural slabs but also in moment-resisting frames. Future considerations in the application of optimisation theories to other design disciplines such as urban planning could have a universal impact on the efficiency of people and vehicle movements. Advanced ideas, such as those using machine learning, will lead not only to assessing damage to structures, but also to the health monitoring of structures. This process applied to drawings will lead to an immediate comparison of drawings to placement of material. This process could also assist directly in design, for example, by learning from wind tunnel studies and applying this learning to the conceptual design of buildings. In the future, these techniques could be used not only for verifying construction but also for automating construction. REFERENCES [1] Diaz A, Murren P and Walker S (2017): ‘Preliminary Observations in the Aftermath of the September 19, 2017 Puebla-Morelos Earthquake’, Skidmore, Owings & Merrill LLP, San Francisco, USA. [2] Ren S, Kaiming H, Ross G and Jian S (2015): ‘Faster r-cnn: Towards real-time object detection with region proposal networks’, Advances in Neural Information Processing Systems, pp 91-99. [3] He K, Zhang X, Ren S and Sun J (2016): ‘Deep residual learning for image recognition’, Las Vegas, USA, Proceedings of the Institute of Electrical and Electronics Engineers (IEEE) Conference on Computer Vision and Pattern Recognition, pp 770-778. [4] Chen LC et al (2016): ‘DeepLab: Semantic Image Segmentation with Deep Convolutional Nets, Atrous Convolution, and Fully Connected CRFs, Institute of Electrical and Electronics Engineers (IEEE) Transactions on Pattern Analysis and Machine Intelligence, Volume 40, pp 834-848. [5] SAP2000 Nonlinear (v 9.1.3) (2005): Computer Program for the Three Dimensional Analysis of Nonlinear Structures, Computers and Structures Inc (CSI), Berkeley, California, USA.

(This article is based on a Keynote Paper authored by Mark P Sarkisian, Partner, Skidmore, Owings & Merrill LLP, San Francisco, USA, and presented by Eric Long, Skidmore, Owings & Merrill LLP, at the 44th Conference on ‘Our World in Concrete & Structures’ held in Singapore, from 29 to 30 August 2019. The conference was organised by CI-Premier Pte Ltd) 38

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A jury of nine experts headed by Nirmal Kishnani, Associate Professor of Architecture, School of Design & Environment, National University of Singapore, will evaluate entries in the 6th International LafargeHolcim Awards for the Asia Pacific region. The awards are given to Nirmal Kishnani will head real projects as well as the jury. bold ideas that combine sustainable construction solutions with architectural excellence. The competition offers a total of USD 2 million in prize money and is open for entries until 25 February 2020. In Asia Pacific, the jury includes Nirmal Kishnani (Head) as well as Chanasit Cholasuek, Co-Founder of stu/D/O Architects (Thailand); Christopher Lee, Co-Founder & Principal, Serie Architects (London, Mumbai, Singapore and Beijing); Nondita Correa Mehrotra, Principal at RMA Architects (India); Richard Hassell, Co-Founder of WOHA (Singapore); and Erwin Viray, Head of the Architecture Sustainable Design Pillar at the Singapore University of Technology & Design (Singapore). The jury will be complemented by members of the Academic Committee of the LafargeHolcim Foundation, namely Marilyne Andersen, Full Professor of Sustainable Construction Technologies, Swiss Federal Institute of Technology Lausanne (Switzerland) and Philippe Block, Professor of Architecture & Structure, Swiss Federal Institute of Technology Zurich (Switzerland), together with Sandra Boivin, R&D Support Director, LafargeHolcim Innovation Center (France). Hosted by the National University of Singapore, an associated university of the LafargeHolcim Foundation, the jury will rank submissions using the five ‘target issues’ for sustainable construction - innovation and transferability (progress), ethical standards and social inclusion (people), resource and environmental performance (planet), economic viability and compatibility (prosperity), and contextual and aesthetic impact (place). The competition recognises projects and concepts from architecture, engineering, urban planning, materials science, construction technology, and related fields. A comprehensive ‘step-by-step’ guide explains the evaluation criteria and illustrates how to enter the competition, at www.lafargeholcim-awards.org. Since 2003, the LafargeHolcim Foundation advances the discourse on sustainable construction, mainly through its awards. The foundation is an initiative of LafargeHolcim, a global leader in building materials and solutions.

PROJECT APPLICATION

Upgrading the Bisagno Stream

in Genova for increased safety A section of the bed of the waterway in Italy was widened and reinforcement rods were protected against corrosion.

An overview of the area where the work was carried out.

After almost three years of work, the upgraded Bisagno Stream, which flows lengthways through the city of Genova in Italy, and cuts it in two, was equipped with new safety features, before being handed back to the city in January 2018. The work included the completion of a 200 m long channel along the stream, at a cost of around EUR 24.7 million. The work proved to be highly complex and had to be carried out in complete safety. In fact, the end part of the stream flows through a densely populated area with a highly frequented railway hub. The work was carried out in three separate stages and the traffic routes had to be modified 21 times. The work was carried out by ATI-CSI (Consorzio Stabile per le Infrastrutture), SIRCE SpA, VIPP Lavori Speciali Srl and Trecolli SpA, and included the completion of work on the road going over the stream and increasing the streamâ&#x20AC;&#x2122;s capacity to handle run-off water. The road going over the stream was also upgraded to withstand loads and to improve the flow of traffic. To obtain these results, ATI enlarged the hydraulic section of the stream by lowering the bed of the waterway and reducing the thickness of the road deck, while main-

Excavation and construction work in progress, to widen a section of the bed of the Bisagno Stream. THE SINGAPORE ENGINEER September 2019

PROJECT APPLICATION

taining the existing banks by increasing the section of the structural elements and reconstructing the internal cavity walls and the road over the stream.

The service areas were also reorganised, which included building tunnels for the various service equipment and new crossways inside the road deck.

Specifically, the work included demolition of the old decking dating back to the 1930s, lowering the bed of the stream by around 2 m, building footings under the existing banks of the stream and building a new road deck, all in compliance with the latest norms and standards, including norms covering seismic upgrading interventions.

Thanks to the work carried out, the capacity of the stream was increased from 450 m3/s to 850 m3/s with a free-board (the gap between the surface of the water and the underside of the road deck) of 1 m. Around 20 specialised building companies took part in the work, including Mapei, with a workforce of more than 250 people. Once demolition work was underway on the foundation slab of the road over the stream on the west bank, jet grouting and preparation work on the new foundation slab could commence. The new bearing walls for the new road over the stream were then built.

Galvanic cathodic protection for the reinforcement rods To protect the reinforced concrete abutments and bearing walls, as prescribed in the technical specification, galvanic cathodic protection was provided by using MAPESHIELD I 30/20, from Mapei. MAPESHIELD I is a solution developed by Mapei to protect reinforcement rods in repaired reinforced concrete structures, against corrosion. It also offers a number of advantages if it is used to prevent corrosion in new reinforced concrete structures, particularly those that will come into contact with aggressive agents. The area worked on, in this phase, was the first band of concrete around 2 m high from the bed of the stream. Three anodes were placed every metre along the abutments, at a pitch of 0.7 m, in a vertical direction. Along the dividing walls, on the other hand, three anodes were positioned every 0.9 m, again at a vertical pitch of 0.7 m. In total, around 3,600 anodes were installed.

Preparation work being carried out before pouring the reinforced concrete for the new structures.

The road going over the stream was also upgraded. 40

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The new reinforced concrete structures were further protected by applying a specific Mapei coloured coating. Once the surfaces had been cleaned and checked

MAPESHIELD I anodes (coloured blue) were installed on the reinforcement rods to be protected.

PROJECT APPLICATION

to make sure they were sound, they were treated with the bonding promoter, MALECH, an acrylic, water-based primer, and then painted with ELASTOCOLOR PAINT, an elastomeric paint for crack-bridging protection of internal and external surfaces, with long-lasting elasticity and high resistance to chemicals. MAPESHIELD I MAPESHIELD I is made up of a multi-layered core of pure zinc anodes with a large surface area, covered with a special conductive paste which keeps the system active over the years. After connecting them to the reinforcement rods with metallic stays, a difference in potential is created between the steel and the zinc anodes, which stops corrosion and impedes its occurrence. MAPESHIELD I is particularly recommended for protecting reinforcement rods against corrosion in structures requiring repair work and also offers a number of advantages if installed on new reinforced concrete structures.

INTERVENTION BY MAPEI Project Safety works on the Bisagno Stream, Genoa, Italy Clients Genoa City Council Liguria Regional Council Design Studio Majone Ingegneri Associati Piemontecnica Studio Associato Works direction Giovanni Frongia Main contractor ATI-CSI(Consorzio Stabile per le Infrastrutture) SIRCE SpA VIPP Lavori Speciali Srl Trecolli SpA

INTERVENTION BY MAPEI Period of the intervention 2016-2017 Contribution by Mapei Supply of products for the galvanic cathodic protection of reinforcement rods and protection of concrete surfaces with coloured coatings. Mapei products used Galvanic cathodic protection of reinforcement rods MAPESHIELD I Protective coating - MALECH primer and ELASTOCOLOR PAINT Website for further information www.mapei.com

Solutions for sustainable building At BEX Asia 2019, Mapei presented a range of products and solutions, including waterproofing products, adhesives for tiles and vinyl flooring, protective systems for building concrete structures, systems for prefabricated bathroom units (PBUs), Prefabricated Prefinished Volumetric Construction (PPVC) systems, decorative flooring, and hygienic wall paint. These products and systems are sustainable, with low emission of VOC (volatile organic compounds), and ensure the health and safety of users and building inhabitants (for example, the hygienic paints and the radon- and methaneresistant waterproofing membranes). The solutions offered by Mapei protect structures for a longer service life, which means a lower consumption of materials. BEX Asia 2019 was held from 4 to 6 September 2019, at Marina Bay Sands, Singapore. Solutions for large format thin tiles Mapei introduced ULTRALITE S2, a one-component, highperformance, cementitious adhesive, classified as C2E S2 according to EN 12004 Standards. ULTRALITE S2 is specifically developed for installation of large-sized thin tiles, even though it can be used with all ceramic tiles. Its high buttering capacity ensures that there are no gaps in the adhesive at the back of the tiles, thus avoiding the risk of fracture of tiles during application. It also has a high capacity to absorb deformations in the substrate and in the tiles. Complete waterproofing solutions For roof waterproofing, Mapei launched PURTOP EASY, a ready-to-use polyurethane membrane. PURTOP EASY can be applied with just one single coat. It has high elasticity, good bond strength to substrates and is fully permeable. Besides being resistant to ponding water, it is also resistant to root penetration and UV rays. For basement waterproofing, Mapei presented MAPEPROOF FBT, a synthetic waterproofing membrane with non-woven fabric backing. It can be used with MAPEPROOF FBT TAPE and MAPEPROOF SA TAPE for waterproofing structures below ground level before casting concrete. This product can be fully bonded to concrete with completely watertight overlaps. It is impermeable to radon and methane, making it safe for inhabitants in the building. In addition, it is resistant to root penetration. Galvanic cathodic protection MAPESHIELD reactive zinc anodes create a galvanic shell with the steel, which, as a result, is passivated and remains protected against attack from corrosion. It protects the reinforcement rods even if the concrete around the rods is insufficient and/or is cracked due to shrinkage or external stresses.

This editorial feature is based on an article from RealtĂ MAPEI INTERNATIONAL Issue 74. All images by Mapei. THE SINGAPORE ENGINEER September 2019

PROJECT APPLICATION

Formwork solution for

a subway station in San Francisco When completed, the Chinatown Subway Station will form the northern end of San Francisco’s Central Subway System. The new Chinatown Subway Station will significantly improve access to public transport in some of the city’s most densely populated areas. The architectural requirements presented the contractor with enormous challenges. PERI developed a project-specific solution based on the VARIOKIT Engineering Construction Kit, in order to economically construct the inner lining. The highest point of the oval-shaped underground structure is still 17 m below Stockton Street which is why the construction using the cut-and cover method would have been too cumbersome and expensive. The contractor therefore decided in favour of shotcrete construction, also known as the New Austrian Tunnelling Method, in which excavation work takes place step-bystep, from top to bottom. As more and more soft ground is excavated, temporary reinforcement provides support for the ever-increasing wall surface of the hollow space. Shotcrete applied to the surfaces supported the cavity until the inner lining could be cast in situ.

Project-specific VARIOKIT solution deep underground The solution provided by PERI engineers for executing the enormous 60 m long Chinatown Station with a 15 m diameter stipulated concreting operations in 9 m sections. In order to be able to carry the large and heavy formwork ring, a project-specific formwork carriage consisting of high load-bearing VARIOKIT core components was realised. The pre-assembled formwork elements, comprised of GT 24 formwork girders and plywood formling, also saved weight when compared to using heavier steel formwork. These were lowered from Stockton Street through the site access to a depth of 30 m and then mounted on the rail-guided VARIOKIT Tunnel Formwork Carriage. The hydraulic support of the VTC accelerated shuttering operations after the reinforcement had been placed in position. Concreting took place alternately on both sides, in order to keep the supporting structure balanced. Vibrators mounted on the formwork could also be activated, as required, which ensured uniform compaction of the poured concrete.

easily and quickly carried out by means of the hydraulic support. The tunnel formwork carriage was subsequently pulled along rails, using heavy-duty wheels, to the nextsection. After the first 10 concreting cycles, the tunnel profile changed. Due to the flexible VARIOKIT modular construction system, complete with numerous rentable system components and the VTC Telescopic Prop, the supporting structure together with the other components were easily adapted in order to accommodate the new geometry. Once equipped with the new formwork elements, the final 10 sections could likewise be quickly realised, thanks to the well-coordinated and practised procedures.

Solutions from a single source The VARIOKIT modular construction kit is characterised by its flexibility, high load-bearing capacity of its components and their low weight. The project-specific solution with prefabricated timber formwork panels delivered to the construction site, as well as the large proportion of rentable system components, provided the clients with enormous savings regarding investment, logistics and the amount of work involved. Due to the high adaptability of the system, numerous time-consuming and cost-intensive carpentry solutions could be dispensed with. Construction site support provided by the PERI project support team continuously optimised all work processes.

Different cross-section but same supporting structure Once the procedure had been established, the 9 m sections could then be concreted in five to six hours, thanks to the high permissible fresh concrete pressure of up to 90 kN/m². After each concreting operation, striking was 42

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The high load-bearing capacity of the VARIOKIT system components facilitated the safe transfer of large loads while simultaneously allowing flexible adaptation to accommodate the challenging tunnel crosssection. Image by PERI GmbH.

PROJECT APPLICATION

A trio of cranes deployed in Paris metro station project Special foundation work for the future Kremlin-Bicêtre Hospital metro station is nearing completion. In the French capital, work on the future ‘Grand Paris Express’ metro is currently in full swing. The extension of the Paris Subway Line 14 in the south will connect Orly Airport directly with the current Olympiades terminus. RATP (Parisian Public Transport Authority), to which the Société du Grand Paris has awarded part of the project management for the southern extension, has selected the offer of the consortium led by VINCI Construction associated with Spie Batignolles, to build a 4.6 km tunnel between the future Maison-Blanche railway station in Paris XIII and the Villejuif tunnelling machine shaft. The contract includes the construction of the Kremlin-Bicêtre Hospital metro station and five ventilation and emergency shafts.

Suitable for special requirements To construct the diaphragm walls at the Kremlin-Bicêtre Hospital site, several machines are working simultaneously, including a SENNEBOGEN Duty Cycle Crane 6140 E with a mechanical diaphragm wall grab and a second with a rotoforeuse hydromill. The 1.54 m thick walls are reinforced with frame cages weighing up to 70 t and 50 m long, which are lifted and erected with the SENNEBOGEN 7700, a 300 t capacity crawler crane as service crane.

Two SENNEBOGEN Duty Cycle Crane 6140 E cranes, one with a mechanical diaphragm wall grab and a second with a rotoforeuse hydromill, are working simultaneously to construct the diapharagm walls at the Kremlin-Bicêtre Hospital site.

Spie Batignolles Foundations, which has already owned two SENNEBOGEN 6140 HDs for two years, expanded its fleet for work on Line 14 South at the beginning of 2019 with a third machine of the same type, this time equipped with a mechanical 25 t diaphragm wall grab. Thanks to its 350 kN free fall winches and its versatility, the SENNEBOGEN 6140 HD meets the needs of this new Parisian construction site in an urban environment, close to the A6 motorway and the Kremlin-Bicêtre Hospital. Since their first operation, the SENNEBOGEN 6140 heavy duty cycle cranes have already proved their worth in several major Grand-Paris Express projects, particularly on Line 15 South. The teams are confident that the cranes used in the urban environment with their Tier4f compliant engines will reduce the environmental impact. Here, in the underground station of the Kremlin Bicêtre Hospital, the Spie Batignolles Foundation equipped one of the 6140 E cranes with a 35 t, 550 kW XL rotoforeuse hydromill of the latest generation. The 708 kW motor of the duty cycle crane enables the drilling tool to be driven, which is controlled by the machine operator, thanks to the modern and ergonomic touch screens and control panels in the cab. The grabs work at depths of up to 50 m on this job site, and the hydromilling machine on the 6140 E can even reach twice that depth, that is, up to 100 m.

The SENNEBOGEN 7700 R-SL crawler crane, with a capacity of 300 t, is used for the lifting and handling of reinforcement cages. THE SINGAPORE ENGINEER September 2019

PROJECT APPLICATION

Building the world’s longest and deepest subsea road tunnel It is part of the reconstruction of the Coastal Highway Route E39 in Norway. Norway is well-known for its breathtaking coastline, with high mountains and deep fjords. But there is a downside to this spectacular landscape. At the moment, travelling along the Coastal Highway Route E39 between Kristiansand in the south and Trondheim in the north is a journey of around 21 hours. Yet about a third of Norway’s 5.3 million people live along this highway, which is also an important trade route for Norwegian businesses, as some 60% of the country’s export goods are produced on the West Coast. In addition, when the E39 leaves Norway, it proceeds to Denmark, making it an important entry point to the rest of Europe. And for truck drivers, driving through this stretch of coastline can be hard. “I go and get the rocks at the construction site and then I drive it to the other sites in need of material”, explains Håvard Langåker, a truck driver.

building techniques, is Norway’s biggest ever infrastructure project. The reconstructed highway will reduce the journey time between Trondheim and Kristainsand, from 20 hours to just 11 hours. The Rogfast Tunnel, expected to be completed in 2026, is a big part of this improvement. Set to be the longest and deepest subsea road tunnel in the world, it will stretch 27 km in length and 392 m below sea level at its deepest point. But building tunnels at this depth poses a challenge. In order to make the journey as safe as possible for road users, construction will include the building of two separate tunnels for traffic flow. In addition, at every 250 m, there will be passages that connect the two tunnels, allowing for a quick and easy exit in case of emergencies.

“On the road, I need to wait for ferries, stand in ferry lines, deal with cancelled ferries and narrow roads. We have island and fjords with roads which follow the coastline. It takes the longest way, not the shortest, therefore it is quite time-consuming”, he added. But all this is about to change. The reconstruction of Coastal Highway Route E39, at a cost of USD 39 billion, using new bridge and tunnel

This pioneering project is set to cut travel times in half. 44

THE SINGAPORE ENGINEER September 2019

The Rogast Tunnel will be built as deep as up to 392 m below sea level.

WES 2019:

IES UPDATE

Gathering global engineering experts to create sustainable, liveable future cities through technology

(From left) Mr Melvin Yong, Er. Dr Lee Bee Wah, Ms Jo Tyndall and Dr Vivian Balakrishnan listen intently as the EIC team from the School of Science and Technology introduce their winning project.

IES kicked off the World Engineers Summit (WES) 2019 on 28 August 2019 at Suntec Singapore Convention and Exhibition Centre, with Dr Vivian Balakrishnan, Minister for Foreign Affairs, gracing the opening ceremony as the guest-of-honour. Themed “Engineering Future Cities – Harnessing and Managing Technologies to Improve Quality of Life”, the fourth edition of the biennial conference saw more than 800 international engineers gathering to exchange knowledge, expertise and ideas in using and managing of technologies to build greater sustainability, liveability, economic security and climate resilience for cities. It also marked the inaugural collaboration between IES and The Institution of Professional Engineers, Japan (IPEJ), with both institutions jointly organising a conference track that covered building smart energy and sustainable cities in Asia. Commemorating this occasion, Mr Yamazaki Jun, the Ambassador of Japan to Singapore, spoke at the opening ceremony, where he noted the strong bonds between both countries and the opportunities available ahead in the global digital future. Other plenary speakers included Ms Jo Tyndall, New Zealand High Commissioner to Singapore, Mr Melvin

More than 800 engineers from around the world attended WES 2019 to learn from each other and work together on utilising technology to build sustainable, liveable and resilient future cities.

Yong, Assistant Secretary-General, National Trades Union Congress (NTUC), Mr Tan Kok Yam, Deputy Secretary, Strategy Group, Prime Minister’s Office; and Professor Shabhaz Khan, Director for Regional Science Bureau for Asia and the Pacific, UNESCO. “WES 2019 will cover a multitude of interests and perspectives with the aim of creating greater momentum and spawning new collaborations amongst engineering communities around the world to engineer sustainable and liveable cities of tomorrow,” said Er. Prof Lim Kok Hwa, WES 2019 Conference Chair. THE SINGAPORE ENGINEER September 2019

Apart from the project presentations, awards, and performances, dinner guests also picked up the Japanese morning workplace exercise routine, courtesy of our friends from IPEJ.

The Conference Dinner was held the next evening, attended by Dr Amy Khor, Minister of State for the Environment and Water Resources and Health.

local engineers to advancing engineering and enhancing quality of life of Singaporeans.

A fitting close to two days of intense discussions and knowledge exchange, participants also heard from the budding engineers of the future in the form of the Energy Innovation Challenge 2019 champion teams, who introduced their projects to the gathered guests. It was also a night of recognition as IES announced the winners of the Prestigious Engineering Achievement Awards 2019, recognising the outstanding contributions of

This year’s winning projects have demonstrated excellence in tackling pressing issues of climate change and urbanisation, with technological innovations to reduce carbon emissions; enhance energy and water resilience; and improve waste management efficiency. On 30 August, the final day of the conference, technical site visits to Marina Barrage, the SUTD Digital Manufacturing and Design Centre, and the SUTD-MIT International Design Centre were held.

IES Prestigious Engineering Achievement Awards 2019: Recipients and project descriptions CATEGORY: APPLIED RESEARCH AND DEVELOPMENT

EWaT – Electrochemical Treatment Targeted at “Hard-To-Treat” Industrial Wastewater by NUS EWaT is based on NUS patented graphene-coated electrode (with improved reagent yield by 40%) to treat the organic content of all kinds of real “hard-to-treat” wastewater, including chemical, electronics, pharmaceutical and waste sludge from animal husbandry.

Integrated Multi-Physics Approach for Urban Microclimate Modelling by HDB and A*STAR – Institute of High Performance Computing and Institute for Infocomm Research The Integrated Environmental Modeller (IEM) is a first-of-itskind tool that allows user to model how various environmental factors such as solar, wind and temperature impact each other individually, as well as their combined effects on urban plans and design. The tool helps to provide a quantitative and scientific assessment for the environmental performance, allowing user to understand the different trade-offs involved to aid decisionmaking in the planning and design process.

THE SINGAPORE ENGINEER September 2019

IES UPDATE

CATEGORY: ENGINEERING PROJECTS

Demonstration Plant for Tuas WRP at Ulu Pandan by Black & Veatch and AECOM A state-of-the-art advanced water reclamation plant (WRP), Tuas WRP, is being designed to produce high-grade reclaimed waters from used-water as part of the Phase 2 Deep Tunnel Sewerage System (DTSS) in Singapore, a monumental project being undertaken by PUB Singapore. The selected treatment concept was validated in a 12,500 m3/d demonstration plant.

Implementation of Pneumatic Waste Conveyance System (PWCS) at Yuhua by HDB The PWCS is an automated waste collection system utilising high speed air to transport household waste from multiple blocks through an underground pipe network to a central location for collection. Besides minimising the need for service diversion, Smart Sensing technologies with data analytics capability was integrated to optimise the frequency of waste collection and system operations.

CATEGORY: TECHNOLOGY INNOVATION

Development of Floating Platform for use in Reservoir and Coastal Marine Conditions by HDB To support the acceleration of solar adoption in Singapore, the Housing & Development Board (HDB) is studying the use of its floating modular system to hold solar panels on water bodies to harvest solar energy. The floating solar system in Tengeh Reservoir is the first-locally designed system, as well as the only system that can be deployed in freshwater and coastal conditions. The system is modular, lightweight and able to support high payload. Key unique feature includes the use of corrugated surface to provide rigidity and strength.

Next Generation of Hybrid Air Conditioners for Tropics â&#x20AC;&#x201C; Cooling With Heat by Ecoline Solar Pte Ltd Ecoline Solar and NUS have jointly developed a new generation of hybrid solar-thermal air conditioners that uses heat from the Sun and surrounding ambient heat to deliver thermal-comfort air. This hybrid system is an innovative, pragmatic, and proven way to achieve 30 per cent or more energy savings compared to other high-efficiency air conditioners.

THE SINGAPORE ENGINEER September 2019

IES-INCA signs

IES UPDATE

MOU with Origgin In April this year, the IES Incubator and Accelerator Programme (IES-INCA) signed a Memorandum of Understanding with venture building and investment company Origgin to strengthen and expand the pipeline of incubatees into the programme. Through this partnership, both parties hope to nurture the next generation of deep tech engineering start-ups and discover global business opportunities, which will be accomplished through Origgin’s Venture Co-Creation process (VCC).

the list of potential VCC companies to IES-INCA. If accepted by IES-INCA, these incubates will receive the next phase of the startups development and growth, where they will receive mentorship, funding, training etc. This ensures successful commercialisation and potential increases in scale based on their business plan, which will be developed jointly with their mentors, within 12 months.

VCC was founded by Origgin with the aim of creating and guiding startups to address business pain points, facilitating their journey towards success. This involves working together with industry partners and leading research institutes in Japan, Singapore and the rest of the world to discover new opportunities for growth by innovation. Since mid-2017, VCC has successfully spun off 24 deeptech startups across various industries from A*STAR and the Institutes of Higher Learning. Under the MOU with IES, Origgin will focus on cocreation with IHLs and research institutes and provide

(From left) Er. Edwin Khew, Chairman, IES-INCA Board; Mr Clarence Tan, Founder and Director, Origgin; Mr Andy Wee, General Manager, IES-INCA; and Ms Emily Tan, Acting Head of Secretariat, IES, chat briefly before the signing ceremony.

Both IES-INCA and Origgin will collaborate to nurture the next generation of deep tech engineering start-ups and discover global business opportunities.

ADVERTISERS’ INDEX

IES 53rd Annual Dinner –––––––––––– Outside Back Cover

26th ITS World Congress ––––––––––––––––––– Page 11

IES Membership ––––––––––––––––––––––––––– Page 29

Building and Construction Authority ––––––––––– Page 01

MultiNine Corporation Pte Ltd –––––––– Inside Back Cover

Cementaid (S.E.A.) Pte Ltd –––––––––––––––––––– Page 05

Singapore Institute of Technology –––––––– Page 24 & 25

Delta Energy Systems –––––––––––––––––– Page 30 & 31 (Singapore) Pte Ltd

Singapore University of –––––––––––– Inside Front Cover Social Sciences

THE SINGAPORE ENGINEER September 2019