Tall Office Building_Design and Construction Proposal_AAT

Design Development Proposal for a Tall O ffice Building in Melbourne CBD

Team Members

Shaun Lim 1155246 825663 800376 Kai Lin

Fanshunze Yang

Contents

Part 1 – Project Syn opsis

1.1 Vertical Strategy (Sh aun Lim)

1.2 Structural Concept (Kai Lin)

1.3 Facade Concept (Fanshunze Yang)

Part 2 – General Arrangement Drawings

A1.1: Site Plans and Design Response Massing Concepts A1 2: Architectural Plans and Sections A1.3:

A2 1: Typical Podium Floor Framing

A2.2: Overall Section and Typical Tower Floor Framing

A2.3: Typical Floor Sections

A2.4: Structural concept diagrams & 3D modelling

A3.1: Overall Elevations

A3.2: Enlarged Elevations

A3.3: Façade concept 3D Model

Part 3 – Detailed Design Drawings

A4.1 Podium Façade: General A rrangement

A4.2 Podium Façade: Details

A4.3 Typical Office Façade: General Arrangement

A4.4 Typical Office Façade: Details

A4.5 Typical Hotel Façade: General Arra ngement

A4.6 Typical Hotel Façade: Details

PROJECT SYNOPSIS

1.1 VERTICAL FEASIBILITY

STRATEGY

Author Shaun Lim

thor Lim

Our project is a building that responds to the view of Port Phillip Bay, West Melbourne, and the City Centre of the Melbournian CBD. We seek to embrace these views through the arrangement of the tower floorplates and external façade We have also taken into consideration natural lighting and wind conditions which will be addressed separately

Our project consists of a skyscraper with a podium, tower, and crown. The tower core varies throughout the height of the building, occupying a square to rectangular area with 18 lifts servicing 4 zones of low-rise, mid-rise, high-rise and sky-rise of overall 59 floors; this includes 3 mechanical floors and a view level at the crown. An efficiency of 80.88% in tower was achieved. The building’s podium is accessible to the public. It consists of a split hotel and office lobby, with a café and shopping spaces. Due to the vicinity of public transport like the tram stops and Southern Cross Station; we believe that the podium has the potential to be a gathering place for the community in the area. The tower of the building consists of corporate office spaces, and a hotel with rooftop bar and dining. The rooftop bar and dining will be within the crown of our building, taking advantage of the 360-degree viewing platform at the top of the tower

The location of the project site establishes our tower within the vicinity of multiple existing skyscrapers opposite Southern Cross Station The tower of our project stands at 59 levels, to allow the high to sky-rise of the tower an unrestricted view of the Port Phillip Bay area. We believe that would provide an incentive for guests staying at the hotel situated in our building. Our intended office levels on the low to mid-rise of the tower are designed to have a larger Net Lettable Area (NLA) as we believe that would provide the incentive for corporate offices leasing a space in the building.

The external façade of the building is angled on some façades to provide optimum lighting while still maintaining an efficient gross floor area (GFA) within the tower’s internal plates We have chosen a central core as we believe it to be the best one applicable to our design intent, of having an unrestricted view to the surroundings of the tower. We believe that by having a central core, our tower will also allow for both a sufficient GFA and height By having more natural lighting, the building’s interior spaces will be of higher quality.

The form of our building responds to the strong prevailing wind from the north. The podium acts as protection from the downwash from the tower, while at the same time the angled form of the external façade reduces the stress from the windflow seperation hitting the tower.

1.2 STRUCTURAL CONCEPT

Our project is using the diagrid structural system, which has a combination of the steel exterior diagonal frame, vertical columns and concrete centre core. This structural system first applied to the John Hancock Tower in Chicago in 1969 by Fazlur Khan. We took the John Hancock tower as a precedent of structure and learned the structural system from it.

There are several reasons why we have chosen the diagrid structural system rather than other outrigger systems and tubular systems. The first advantage of the diagrid system is the reduction of the number of perimeter columns. Typically, columns have spaced no more than 4.5m apart. However, the composite of the diagonal frame and vertical columns allows 9m spacing between columns in this case. The efficiency of structural elements required maximized the transparency of the façade and the amount of daylight. Therefore, it provides less obstruction to the views of Port Phillip Bay, and it becomes one of many reasons.

The diagonal frame has more excellent capability of resistance against the lateral forces than other traditional tubular systems. The unique composition of structural frames provides lateral stiffness efficiently, and the system offers an architectural aesthetic. The diagrid system is rarely applying on skyscrapers in Melbourne, so it would make our tower unique. As the conclusion of Panchal and Patel’s journal 1demonstrated, the diagrid system has more resistance to the dynamic effects, and the top storey sway is very much less as compared to other tubular frame systems. We purposed to design a 250m high skyscraper, so the negative effect of lateral forces became one of the most significant issues we need to consider. Thus, we chose this structural system to minimize the impact of dynamic effects.

The west side façade of high-rise level and the north side façade of the skyrise level are angled and offset six building modules (9m). The design strategy optimized the view of hotel levels. However, it limited the structural systems we can use. The outrigger system needs to locate the outrigger frames on 4/5 and 2/5 of building height to approach the 1/25 roof level drift. But nearly top 36% of the tower has angled façade. Therefore, we selected the diagrid system to approach the design we want. The diagrid system has excellent adaptability and flexibility in architectural design. It breaks the limit of the traditional tubular system and outrigger system as it allows towers to be curvier and more flexible. The capital gate tower in Abu Dhabi is a great example. Therefore, we choose the diagrid system to deal with the angled façade.

As the vertical load on concrete core diminishes, the different thickness of concrete walls is using to improve the efficiency of material use. We currently make the thickness of core walls as 750mm at the base, then 600 at mid-rise and 450 at the high-rise.

1.Panchal, Nishith B., and Vinubhai R. Patel. "Diagrid structural system: Strategies to reduce lateral forces on high-rise buildings." International journal of research in engineering and technology 3, no. 03 (2014): 374-378.

Figure 1, Render of the diagrid structure system

Figure 2, John Hancock tower by Fazlur Khan

Figure 3, Structural elements of diagrid system. Angelucci, Giulia, and Fabrizio Mollaioli. "Diagrid structural systems for tall buildings: changing pattern configuration through topological assessments." The Structural Design of Tall and Special Buildings 26, no. 18 (2017): e1396.

Figure 4, 60 Storey structures with various diagonal angles. Diagrid, From: http://ae390g6diagrid.weebly.com/parameters.html

Figure 5, Plan of high-rise hotel floor, Kai Lin

Figure 6, Capital Gate in Abu dhabi Designed by RMJM Figure 7, Precedents of diagrid structural system.

1.3 FACAD ECONCEPT

Building Envelope Design intentions and approaches:

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Base on the idea of providing a reliable and effective building envelope, the curtain wall is the most common solution which allows enough daily sunlight and great views facing the bay. We applied two kinds of glazing systems to the project, unitized system for tower including office and hotel division, and cable net system for the podium to allow maximum strengths and transparency on the ground level.

The unitized system is fixed at the top but flexible at the bottom, connected by stack joint, to follow the slight movements by lateral force. The façade is behind diagrid members, fundamentally connected and supported by the structural columns sitting around the tower. Such decisions of letting the diagonal exterior frame to be exposed are to ensure the lightweight of façade and avoid extra structural pressure. Additionally, to dissolve the contrast between vision and spandrel panel, we are using “shadow box” to detail the spandrel panel and hide the floor slab behind it. All the essential installations such as fire stops and insulation are considered and applied to the façade. To ensure the aesthetic experiences of users and clients, we also considered the room for finishing elements, for instance, the gap for pelmet and suspended ceiling to hide the structure bondeck above.

As the floor slabs have variations on the area because of the core gets smaller on higher levels, the façade of the building has gradient slopes. To make sure of the feasibility of gradient enclosure, we customize some connecting elements’ profiles while keeping structural strengths to follow the slope. Such as the frame of the glazing and the fixing bracket which connects façade with slabs.

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For the shading system, we mainly applied the system two sides of the building, north, and west since the site is not facing direct north. This could allow us to save the shading on the east façade, which is facing the bay, giving the most view to the users. As all of the shading systems, we having been supported by the structural columns, which means the shading system has the distance to the façade, (the diagrid members is between the shading system and curtain wall), we applied different shading systems for the facades following the basic rule of horizontal for North and vertical for West. For the North façade, the horizontal shading consists of two main parts, shading and capping. The capping is a timber frame supported sloped surface sitting upon the horizontal shading, this could make the shading more effective in summer while hiding the spandrel panel. For the West façade, to work to the site, we applied 45-degree vertical shading systems, the vertical panels are double of floor to floor height, hanging under a horizontal frame, this could allow the universal gap between each shading unit, even for where is the mechanism floor.

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The total height of the project is 272.8 meters. According to the set back policy, the set back from site boundaries to secondary street is 16.368 meters.

UNDERGROUND

PODIUM GF GF 20 4365 2882 66.02%

PODIUM MECHANICAL FLOOR F 1F 8.4 1600

LOW RISE 2F-19F 18 4.2 1600 1240 77.50%

LOW RISE MECHANICAL FLOOR 20F 8.4 1600

HIGH RISE 21F-31F11 4.2 1600 1343.5 83.96%

HIGH RISE MECHANICAL FLOOR 32F 8.4 1600

SKY LOBBY 32F (SHARE) 8.4 1600 1240 77.50%

SKY RISE (LOWER FLOORS) 33-41F 9 4.2 1450 (AVERAGE) 1297 89.45%

SKY RISE (HIGHER FLOORS) 42-53F 12 4.2 1129(AVERAGE) 1027 90.90%

SKY

Horizontal