SHANGHAI TOWER PRECEDENT STUDY
INTRODUCTION
Shanghai tower, is the 5th tallest building in the world at 632 metres. It was designed by the architectural firm Gensler The main architectural design for the tower was to have a building that was a sustainable vertical city, one with a twisting, curved facade, spiralling form which ‘symbolized the dynamic emergence of modern china’. a tower that would include public parks, hotels, offices, retail spaces and cultural facilities. Each split into its individual zones, creating a sense of a neighbourhood community. 121 floors, divided into 9 zones increased inside a glass curtain wall, with a second curtain wall covering the entire structure, essentially a second skin. Sustainable best practise was vital to the designing process And ideas of the project, it was designed for high energy efficiency and sustainability, providing multiple separate zones for office, retail and leisure use. Sustainable Vertical urbanism is also a architectural idea of the project, it envisions a new way of inhabiting super-tall buildings and in this case the only super high-rise building wrapped in sky-gardens. It introduces the concepts of ‘vertical community square’ and ‘sky-gardens’.
STRUCTURAL STRATEGY
TASK 10 A
Corner column
Core wall Composite beam
Super column
Current struct level floor plan
Main structure system
Curtain wall system
Diagram of the six structural layers that comprise the building
Gravity steel columns
Section of concrete composite super column
The shanghai tower lateral system is a “core-outriggersmega frame”and consists of three parts. Concrete Composite Core, Exterior Mega Frame (super columns, diagonal column and double belt trusses) and Outrigger Trusses As a result of twisting geometry the building uses 32-35% less structural materials (concrete and steel) than any other conventional building. Which means there’s a saving of $58 million in materials cost.
As a result of twisting geometry the building uses 32-35% less structural materials (concrete and steel) than any other conventional building. Which means there’s a saving of $58 million in materials cost.
Structural plan layout of typical floors in each zone. Showing columns, belt trusses, walls, out-trigger trusses etc Composite slabs are 155mm
Building systems diagram made on Autodesk
Organisation of regular circular floor plates after curtain walls have been removed
Finite element model of shanghai tower showing structural elements at different levels
Gravity loads transfer path
Lateral loads transfer path
30mx30m Reinforced concrete core Flange wall thickness at the bottom is 1.2m, decreases to 0.5m at the top Outrigger - double stories, there are perpendicular cross ribs that align with belt trusses
Tower Foundation
The tube of core takes 50% of gravity loads
Steel outrigger truss. Super composite column
The mega-frame takes 50% of gravity loads
The mega-frame takes absorbs approximately 47% of shear force and 76% of overturning moment
BELT TRUSS
Radical Outrigger - one story CANTILEVERED END
Steel belt truss for Mega Frame BELT TRUSS
Mega Frame - houses super columns, double belts and steel trusses at every zone. 2nd line of seismic defence
The belt truss of each reinforcement layer transfer the gravity load to the super-columns and corner columns. In addition, in the device layer above the reinforcement layers, multi-channel radial truss are arranged to bear the vertical loads produced by electromechanical device and entertainment layers. In the cantilevered end of the radial truss, there are cables hanging the exterior curtain wall of each zone below
Wind loads reach to the surface of the building, and are transferred to the super columns, thus the mega-frame could carry larger part of the lateral forces
The tube of core takes 53% of shear force and 24% of overturning moment In the reinforcement level, part of the wind load will be horizontally transferred through the outriggers to the concrete core, and then transferred to the foundation vertically.
6m thick c50 4 ksi concrete 955 cast in place concrete plies 1000mm diameter 51m length Working load of 10000 kN
Gusset Plate
Simply on the shear size of the building and its structural elements there are a range of connections that have to be made. Different connections have different design criteria, according to the variation of structure members . which means there’ll be stress state complexity
Gusset Plate of outrigger
Filled board
Chords of outrigger truss
Gusset plates, 120mm thickness Gusset plate design ensures that every rod of the outrigger truss would be anchored strongly in the gusset plate. It also ensures that the joint action of webs and chords of outrigger have enough strength
As a result of the large member force in the belt trusses Long bolt joints of the belt truss are needed in high quantity and length with excellent torsion strength
The members of outrigger bear compress and tension bending. Image shows that area what different levels of stress occurs
Stress/MPa
PASSIVE DESIGN
Double skin acts as an insulation blanket keeping the suns heat out in the summer and the buildings heat in the winter. At the same time letting the maximum amount of light in, reducing the need of artificial light.
ACTIVE ENVIRONMENTAL SYSTEMS
Tower structure - The effect of wind load on the building structure is weakened by about 24% by the buildings twisting appearance and asymmetric form. Saving $58 million in structural costs.
Sustainable strategies will mean a carbon reduction of 45 million kg/p.a LEED Gold Certification
Wind turbines installed on top of the tower, 270 turbines with a total a capacity of 135kW producing more than 150,000kWh per year for lighting and public spaces. Wind speeds at 4m/s
Ice storage system is designed in shanghai tower to reduce the operation cost reducing peak load need. When demand is low, electricity is used to freeze or chill water that is stored in tanks on rooftops or inside buildings. Then at peak demand times, the ice or cold water is used to cool air for large office or industrial buildings, meaning they need much less power from the grid. Chiller plants are strategically loaded reducing energy required to pump chilled water
Ground source heat pump used to extract the ambient heat from the earth and turn it into heat for your building. Pipes in the ground contain a mixture of water and antifreeze which is pumped around the loop of pipes in the ground. As the liquid passes around the loop, the heat from the ground is absorbed into the mixture, raising the temperature slightly. When the liquid returns to the heat pump itself, a compressor works to raise the temperature to a higher degree. This heated water passes through a heat exchanger to heat the water for your hot water or central heating in the house, and the cooled liquid returns to the loop to complete the cycle again. This system reduces heat use by 21%.
2,130kW Natural gas fired Co-generation system provides electricity and heat energy to the low zone areas. It is a highly efficient form of energy conversion and it can achieve primary energy savings of approximately 40%.
Water treatment plants that are optimised to recycle grey water and storm water for irrigation toilet flushing and washing of outdoor roads. The system features water treatment plants within the tower, podium, and basement level to reduce pumping energy. Low pressure pumping energy is utilized only to transport the water to each tank. These strategies will result in a 38% source-water consumption reduction. Approximately 675 million L/p.a. 245 Olympic swimming pools
Double facade - the transparent second skin acts as an insulating blanket to reduce energy use for heating and cooling. It harvest and uses daylight, reducing artificial lighting to a minimum Sun shading - both inner and outer curtain walls have selective low e-coating fritted glass providing additional shading
Recycling - 24,000 people means a lot of waste. Recycling systems incorporated certain zones for glass, metal paper and plastics Water cooled chiller system - this acts as the lungs of the building, it controls the tower’s cooling and heating system. Performing real-time complex calculations to optimise energy use based on the current workload and operating conditions.
Intelligent energy - the building systems lower energy cost by monitoring and adjusting systems such as lighting, heating, cooling, ventilation and selfgenerating power. Lighting controls alone save more than approximately $556,000 each year.
LIFE CYCLE DESIGN
ADVANCED MATERIALS
Principle materials for this project were glass, steel and concrete Environmental life cycle engineers sought out local materials that could be harvested and manufactured within a 800km radius of the site. This is sustainable because of reduces transportation related environmental impacts
800 km radius of site
The buildings life cycle is important as the tower was designed to act as a precedent for new and upcoming designs, seeing as it is the first of its kind in terms of size, sustainability and facade construction.
Steel Both the main vertical/lateral structural elements and the floor spanning systems are constructed from steel. Also used as support material for the curtain wall, steel tubes had to be designed to withstand and transfer wind-loads, also load from the glass placed within
Glass The glass used for the tower had to be modified to fit the specifications of the design, e-coating, installation, insulation etc
Concrete life cycle
Steel life cycle
Glass life cycle
75% down-cycle, 20% recycled, 5%landfill
93% recycled, 6% re-use,1% goes into landfill
Glass is 100% recyclable, without losing purity
Pre-cast Concrete All 121 floors are pre-cast concrete set in place. Compilation in 9 zones
Composite Super concrete composite column with embedded steel
Mixed-Structure
MODULAR CONSTRUCTION
Each floor slab for each individual zone is the same size and is simply assembled around the buildings composite core. As referred to in an earlier chapter, as the floors are added the floor above is rotated by 1% starting the twisting in the facade. Floor plates are all prefabricated in a local factory and assembled on site
Glass panels are all cut out in a factory all 20,000+ then transported to site and secured in place in the curtain wall system. There are a range of panel types used in the facade, curtain a alone has 8 panel types which all have to be inserted in the right places
The CWSS is takes the same idea as the floor slabs. The parts are produced and brought on site, then assembled. Each CWSS zone have different dimensions.
Zones are all same height, all modulated to make the construction process faster and efficient
GLASS AND FACADE ENGINEERING
TASK 9
CURTAIN WALL SYSTEM
Staggered glass system Hoop rings
Shanghai Tower has a unique design that comprises of two independent curtain wall systems. Creating thermal buffer zones that improves indoor air quality
Support braces
The curtain wall systems created the possibility for the towers one of a kind sky gardens that are spaced through out the building
Floor plates
Close Detailed section of top and bottom atrium curtain wall connection Three studied façades for the Shanghai tower. ‘Shingle, smooth and stagger.’ Staggered glass system was chosen as the best solution
Glass accounts to 70% of the building and has 20,000+ curtain wall panels Panels are approx: 7’W 18’H and 1ton in weight
To prevent convective current down draft and condensation, tube radiation was integrated into the glazing system
The facade of the building twists as it rises. Making it, the first of it kinds. (More details in the parametric design section) The building uses 14% less glass than a building occupying the same area but in a square design Glass type - Laminated
Sun shading - both inner and outer curtain walls have selective low e-coating fritted glass providing additional shading
Elevation section of the towers glass facade
Section of outer curtain wall
Glass perpendicular to the ground reflects less glass than that angled to the sun. Staggered glass reduced light pollution
Detailed of exterior curtain wall
Detailed section of curtain wall frame connection
Tap connection Inner circular tower
Hoop ring(Outer curtain wall)
Circular floor slab
Outer curtain wall skin
Atrium with green spaces
Inner curtain wall skin
Cam-shaped mechanical floors (refuge)
Cross-bracing
Hoop ring
Mechanical and refuge floor skin
Radial Strut
The facade of the building is made up by an outer curtain wall created through a series of cam-shaped rings rotating around the circumference of the inner cylindrical tower
Radial strut
The facade is one with the architectural ambition of the building, the building would not work and reach the goals set without the facade. The outer curtain wall creates the social atrium, public park spaces within the floors and zones of the building, whilst the inner encloses the living and working areas creating the ideal sustainable environment needed. Simply put the facade is the building and vis-versa. They are near inseparable.
Shanghai Tower is the first building where the gap between the layers will be inhabited, in this case by 10 acres of sky gardens. Landscaped with plants and trees as well as paths and small cafĂŠs, these parks and atriums will provide an escape for workers and residents.
PARAMETRIC DESIGN
TASK 7
Form Parametric design was vital in the design of the tower. It played a pivotal role in assisting the design team in to define the buildings unique form and manipulate, refine its complex geometry. It also allowed the team to understand the projects environmentally responsive high-performance form, façade and structure The towers exterior curtain wall has a horizontal profile of an equilateral triangle and a vertical profile that twists and tapers as it rises, which means that every floor is different, the floor above is rotated 1% and scaled down from the floor below. They are however the same shape. Parametric model design was used to define the buildings complex geometry in order to figure out how the building was going to be constructed.
Through basic data being imputed into the software the optimal angle to create a smooth transition between corners and equilateral sides turned was calculated to be 23.3 degrees.
Rhino with Grasshopper was used to determine and optimize the curvature of the curtain walls corners, in order to meet aesthetic, functional and sustainable criteria. The scaling of the tower was important so parametric design was again used to develop its vertical profile, testing both linear reduction and exponential reduction for the purpose of finding the best method of progressing through the different scales between floors. The geometrical relationship between floors, between curtain panel units could be better understood and subsequently optimised The use of the parametric software lead to the decision of having a rotation value of 120 degrees and scaling of 55% from base to the top, making it the first of its kind.
Facade The facade had to be designed to address the complexity of the site and the conditions. The use of parametric design enabled the design team to develop a system that balanced all aspects of the buildings engineering performance, safety, constructibility and maintenance A main design concept that makes the building stand out is its large open views, this was made possible through the testing of various parameters, including size, shape and angle of panels. Numerous facade panel configurations were studied, three main schemes were derived from the study, ‘shingle, stagger, smooth’. each responded to the geometry of the tower in different ways after extensive parametric tests. The stagger system was eventually used, it shed less sun reflection to surrounding buildings and was also the best solution for fabrication and maintenance.
Horizontal profile study at level 9
Autodesk Ecotect analysis of reflection of the tower. Used to study the physics of light and the effect reflection would have on the surrounding building
Curtain Wall Support structure
Study of tower scaling
Shanghai tower: wind tunnel study scaling models (left) and wind tunnel study rotation models (right)
One zone of the full CWSS model
The support structure address not only the issues and complexities of the towers facade and form but also the complex design of connecting the complex support system to the complex form and facade, and transferring combined loads to the foundation through the building core. Parametric software was used to generate the curtain wall support structure for the entire building, including floor plates and the geometry of steel members. This allowed for the entire building to be extensively tested, making sure the design would actually work. Most challenging design aspect of the project was the top of the tower, which is a split-parabolic curved opening, an opening used for sustainable solutions. Using grasshopper, a steel structure parametric model was designed. Steel geometric data was imputed and transferred through different software to generate the steel structure model. Revit was then used to generate the construction drawings for the crown.
Grasshopper model of the CWSS crown
The rounded form of the towers outer facade uses less glass than a rectangular facade with the same area. Allowing for significant saving in materials cost. If traditional computer-aided design methods were used it would have been extremely strenuous to conceptualize
BIM TECHNOLOGY
FIRE STRATEGY
TASK 10B
The tower is evacuated by zones. Each floor has lifts and evacuation staircases and also an independent mechanical layered refuge floor for every 12th floor.
Fire fighters elevators
Evacuation elevators
The tower is divided into 9 zones, each zone has independent control of increasing pressure and extracting air-flow in case of a fire. The use of passenger lifts aide the evacuation process, the lifts are designed to increase the rate of movement from the floors to the zonal refuge floors. Zonal refuge floors are accessed through independent emergency lifts Emergency elevator shafts are pressurized to keep out smoke and have a dual back-up power supply. Air locks in the double skin facade have also been put in place in order to prevent fire spreading rapidly across the building.
BIM technology was used to refine the design by aiding the architect, engineers and everyone involved in the project collaborate better through various tasks. From architectural, structural and MEP design and coordination, fire safety, construction simulations etc.
BIM modelling of shanghai tower allowed design team to avoid collisions of structure, ducts, shafts etc The design team were able to establish an innovative and efficient work-flow between the parametric software and BIM, aiding multi-discipline coordination
A water system is important in the design of the super tall building, harvested water is used in case of this event Passive water storage tank that cascade with small pumps off the building and are filled. When a fire occurs in any zone the system drains by gravity
Fire fighters elevators Refuge floors
Evacuation elevators Refuge floor Staircase
Safety methods have been integrated into the architectural design, for example the harvest and reuse of rainwater (water reclamation system) Fire fighters elevators Staircase Evacuation elevators
Supplemental exit staircase
BUILDING MAINTENANCE
OTHER TECHNOLOGIES
CONCLUSION
Tuned Mass Damper 1,000 metric tine tuned mass damper neat the top of the tower improves occupant comfort Also reduces wind related accelerations The TMD consists of pendulum frame, TMD mass, viscous damper dices, electromagnetic damping devices and snubbing system
Swing stage machine incorporated to aid in the maintenance of the buildings curtain wall system
Elevator
Section of tower crown 310 kW motor - drives pulley
Role during fire - With the building at full capacity it would take the approximately 2 hours and 18 to evacuate. If elevators are operational, it takes 1 hour and 48 minutes.
Rollers accelerometers and electromagnetic actuators inside rollers counteract vibration and swaying Aerodynamic capsule - reduces air resistance and wind noise at high speeds
13 tonne counterweight
Air pressure control system - stops pressure imbalance in passengers ears Top speed 18m/s 40mph. Making it the fastest in the world
In conclusion I would say that the shanghai tower was an incredible success, it has become a buildings that has broken many rules and accomplished things only thought of prior. Architecturally it is a mind blowing structure and as such has achieved its main idea of creating a sustainable vertical city, one that catered to all its near 20,000 occupants. It has been an international success, once again making Shanghai an emerging architectural city both in Asia and the world. It posed a unique challenge to the designers, construction workers and engineers as there were no precedents to look at however as we can see it was a challenge that has been realised