0. Overview
The Shanghai Tower, located in one of the most important economical areas of Shanghai is without a doubt an iconic structure. Standing at 632 meters tall, it is currently the second tallest building after the Burj Khalifa. It posed a numerous challenges to architects and engineers, as it, as every mega-structure, is unique for its architectural design, engineering methods, but also for the economic and cultural impact. That is why it is worth studying and understanding how the whole process of conception and construction went through. In the upcoming chapters, some main technical points shall be covered and discussed.
Fig. 01 http://skyrisecities.com/news/2016/01/ctbuh-marks-shanghai-tower-completion
The picture above shows the Shanghai Tower’s position in the list of ten highest buildings at the
moment. We also notice in the list the two neighboring towers, Jin Mao and the Shanghai World Financial Center, which shows China’s ambition to invest on high -rise buildings.
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1. Client The Shanghai Tower is the tallest structure in the famous financial district of Lujiazui in Shanghai, China. Planning for this special district began back in 1993, where three high rise buildings were intended (Jin Mao Tower, finished in 1999, Shanghai World Financial Center, finished in 2008 and the Shanghai Tower, opened in 2015). The owner of the skyscraper is the Yeti Construction and Development, which is a consortium of development companies, owned by the Chinese state. Some of these companies include Shanghai Chengtou Corp., Shanghai Lujiazui Finance & Trade Zone Development Co. and Shanghai Construction Group. The means of financing the construction of the tower were shareholders, bank loans and the Shanghai municipality. The estimated cost of construction was 2.4 billion dollars.
http://archinect.com/news/article/1189853 63/megataaaall-shanghai-tower-entersinal-construction- hase
2. Architecture firm The American architectural firm Gensler was the designer of the Shanghai Tower, with the Chinese architect Jun Xia as the leader of the team. M. Arthur Gensler Jr. & Associates,
http://www.ctbuh.org/C ongressCommittees/Loc alSteering/JunXia/tabid/ 3013/language/enUS/Default.aspx
Inc., or shorter referred to as Gensler is an http://www.gensler.com/ architectural firm based in San Francisco, California. It was funded in 1965 and, today, it counts more than 3500 employees, operating in 46 offices, in 16 countries worldwide. Some of the notable projects of Gensler include John F. Kennedy Airport in New York; Ritz-Carlton Hotel, Dubai International Financial Centre; Houston Ballet Center for Dance in Houston, Texas; Tower at PNC Plaza, Pittsburgh, Pennsylvania; Facebook Inc., London.
http://www.gensler.com/projects
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The leading architect, Jun Xia, is the Asia Regional Design Director of the Gensler firm. He was born in Shanghai, studied in the Tongji University and then in the University of Colorado. His main goal was to aid the architectural and urban development of his hometown, and as a local with great international experience, was able to start a Gensler practice in China. The ability to render early designs into three dimensional drawings, in order to give his clients a clear understanding of the projects, has made him very well accepted by investors worldwide. Other works by Jun Xia include Beijing Chang’An International Center, Shanghai Pudong Development Bank, Chartered Tower, Dongyin Center, JW Marriot Hotel, BM Plaza, Yangtze International Financial Center, and of course, the Shanghai Tower.
3. Structural Engineers The structural design was provided by Thornton Tomasetti and Tongji Architectural Design (Group) Co Ltd., as the engineer on record. Thornton Tomasetti is an American structural engineering consulting firm, based in New York City. It specializes on structural engineering, façade engineering, construction, sustainability, renewal, forensics, https://www.thorntontomasetti.com/ transportation, etc and is responsible for some of the most famous high-rise building. Taipei 101 (Taiwan), the Petronas Towers (Malaysia), New York Times Building (USA), Americas Tower (USA) are just a few of the skyscrapers designed by Thornton Tomasetti. Other works include stadiums and convention centers, such as American Airlines Arena, AT&T Park, Baku International Stadium, Basra Sport City, Yankee Stadium, Ford Center; renewal works, such as the Façade rehabilitation of the Chrysler Building, structural rehabilitation of the United States Capitol Dome and works like investigation and property loss consulting.
https://www.thorntontomasetti.com/projects/
The firm has also numerous prestigious projects under construction, such as 102 Incheon Tower in South Korea, the Federation Tower in Moscow, Russia; Wilshire Grand Tower in L.A, California; Ping An Finance Center in China and, of course, the famous Jeddah Tower in Saudi Arabia, which is going to be, when finished, the tallest structure in the world at 1008 meters.
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4. HVA engineering The planning and design of the mechanical, electrical and plumbing systems in the Shanghai Tower is done by Consentini Associates, a famous firm based in New York City and Aurecon, an Australian firm. Consentini Associates was founded in 1951 and since then has taken over prestigious projects all over the world. Some of the notable works are John F. Kennedy Library and Museum, John Hancock Tower, Solow Building, Disney Animation Building, Guggenheim Museum Bilbao, Time Warner Center, Walt Disney Concert Hall and New World Center. Aurecon is an engineering firm based in Australia and South Africa. It was founded in 2009 as a merger of three different companies, Africon, Connell Wagner and Ninham Shand. Their main focuses are environmental design, telecommunications, water systems, energy, etc. Some of their most notable projects include City of Dreams Casino in Macau; The Sail at Marina Bay in Singapore; Eureka Tower in Australia; the Qatar Science and Technology Park in Qatar; Berg Water Project in South Africa, etc. On the Shanghai Tower, Consentini Associates and Aurecon worked closely with the architects to provide the tower’s sustainable design and technological innovation. The atrium buffering zone was used
to reduce cooling costs but also to minimize stack effects. There were also incorporated a numerous of technological devices such as heat recovery systems, multiple central plants for low transport energy and heat transfer and overhead variable air conditioning system with demand-control ventilation. Heating is provided by geothermal systems in the basement.
5. Construction company The construction manager company was Shanghai Jianke Engineering Consulting Co., Ltd., which is a local firm of engineering and construction. Other firms involved in the construction of the tower were Shanghai Construction Group; Aurecon for the Façade installation; Rolf Jensen & Associates for fire design; STS Consultants, Ltd for foundation design; Arup, life Safety;Edgett Williams Consulting Group Inc.for vertical transportation design.
6. Important numbers concerning the building THE SHANGHAI TOWER Construction started Completed Duration of planning Estimated cost Height to tip Height occupied Floors above ground Floors below ground Usable area Elevators
29 November 2008 6 September 2015 2006-2008 2.4 billion $ 632 m 561.3 m 128 5 420 000 m2 106 4
20.6 m/s 258 1794 1200 tons
Max. elevator speed Number of hotel rooms Number of parking spots Heaviest damper
7. Architectural details The main feature of the architectural design of the tower is its spiraling effect, which symbolizes the dynamic change and development of modern China. That is why the tower’s
geometry
is
one
of
its
main
architectural features. As it is shown in the picture, the horizontal profile of the building, has a shape derived from an equilateral triangle. Two tangent curves were drawn to create the curvature. There are only two variables that drive the horizontal geometry of the tower: the radius of the circle and its location relative to the triangle.
Fig. 7.1 http://images.autodesk.com/flashassets/thegallery/galleries/shangha i_tower/2.concept/images/Shanghai_Tower_Concept_1.jpg
The vertical profile is an extrusion of the horizontal. For practical and stability reasons it was necessary to keep a wider area in the first third of the towers height and to construct it slenderer as the height increases. Overall, there was a reduction of about 55% of the area in the upper part of the building. This also was a good factor in the functionality of the building. The first third, with a larger area and span is suitable for markets and offices, while the upper part were practical for hotel rooms. The rate of twist was also an important factor in the design of the tower. The principal is to twist the main shape to a certain degree. In the final design, after testing different models, it was decided on a rotation of 120o. This design also does a great job in reducing the lateral wind load and this was the main condition on the design. Figures 7.2 and 7.3 show different models analyzed and the final and optimal design chosen by the architects. Finding on optimal shape was an architectural challenge, because it required lots of considerations and testing, making the design not so flexible in terms of geometry and spatial dimensions. Fig. 7.2 http://www.arch2o.com/case-study-bimimplementation-in-shanghai-tower/
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Fig. 7.3 http://www.arch2o.com/case-studybim-implementation-in-shanghaitower/
Fig. 7.4 http://www.arch2o.com/case-studybim-implementation-in-shanghaitower/
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As shown in the images above, the final design was the result of many test and simulations. The most significant ones were made in Wind Tunnels with scaled down models. Two different models were constructed for this purpose, one in the scale of 1:500 and one on the scale of 1:85. The test took into account the local climate and even typhoons. The results of these test showed that a shape 55% tapered and 120o rotated would not only reduce the structural wind loading by 24%, but would also save 50 million dollars from structure budget.
Fig. 7.5 http://www.arch2o.com/case-study-bim-implementation-in-shanghai-tower/
The Shanghai Tower is divided into 9 functional zones, with each zone taking 12-15 floors. There is a public space or an atrium for each zone with balconies and social areas. The first zone is consist of stores, shops and markets and it is connected to the commercial zone and to the activities of the district. In the upper part of zone 1 there are mainly restaurants. The zones in the middle part of the building are office spaces, while the hotel is situated in the top with the observation deck. The picture below shows a schematic division of the building uses. The mixed use of the building was a key factor influencing on the planning of interior spaces, but also the tapered profile required to constantly change the arrangement of interior floor plans. In this fact, the zonal division of the tower helped, so floor plans for each zone remain the same as the purpose of the floors also remain the same within one zone. The idea of sustainability was also an important one. The architects had to think on how to make reality the idea of a vertical forest in a building of this magnitude. They succeeded while implementing the atrium areas, which are social common areas with green elements, such as flowers and plants. The atriums are open to the general public and are expected to be one of the key touristic sites in Shanghai,
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Fig. 7.6 http://www.arch2o.com/casestudy-bim-implementation-in-shanghaitower/
8. Structural details The Shanghai Tower is currently the second tallest building in the world and the tallest in China, therefore its structural design was a big challenge. The architects at Gensler worked closely with the engineers at Thornton Tomasetti in order to specify the best shape and model. The final design was obtained not only in terms of architectural standards, but, as shown above, mainly by the structural and load-bearing requirements. Being located in a geographical region with high risks, such as: powerful winds and typhoons, constant earthquakes and clay-based soils typical of a river delta, this tower was not a conventional building and
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the engineers had to work hard and sometimes to think out of the box in order to deliver a sound, reliable and economical design.
Fig. 8.1 http://www.metalocus.es/en/news/shanghai-tower-last-step-construction
The structural system of the Shanghai Tower, as shown above, is made of a main core inner tube and an outer mega frame consisting of composite super columns, outrigger trusses and eight two story high double belt trusses. On the Khan chart, this building has an outrigger braced system. As in most megastructures, the core is the main lateral load bearing element. It is built in a reinforced concrete design, with a base cross section of 30 square meters, gradually reducing as the height increases. Surrounding the core, there are twelve steel-concrete composite super columns, two on each side and four additional ones in the diagonal direction. The diagonal columns were implemented in the design in order to reduce the distance between the columns. In the final version, each of these elements stands 25 meter away from its neighboring column. The structure used the nine functional zones to implement a “wedding -cake” concept. In each of these zones an individual tower starts. This is the way the slenderness of the tower is achieved and it offers a structural stability due to the reduced weight as the height increases. In between these zones, there are two-story areas that are used to house the technological equipment of the zone, such as plumbing, heat and electrical. These floors serve also as safe evacuation areas in cases of emergency. Enclosing these areas, there are double belt steel trusses, which serve as a connector between the columns. In a similar way, there are outrigger trusses connecting the core to Fig. 8.2 http://www.arch2o.com/case-study-bimimplementation-in-shanghai-tower/ the outer structural frame. These radial trusses serve 9
also as a support for the special glass façade. The main principal used to design these components was the continuation of forces and the uniformity of stresses. This ensured the different zones to act as a single structure. The floors are constructed as composite components. They have a permanent steel formwork at the bottom, which supports the concrete slab. The seismic impact was also a very important issue in the design phase of the structure. As the foundations lay on clay, a seismic analysis was crucial in order to evaluate the impact of an earthquake. This was achieved via FEM based computational methods, most specifically using the Abaqus software to generate a 3D FEM analysis. The final project was planned to meet the requirements of the China Seismic Design Code. a. Core inner wall system
Fig. 8.3 https://www.linkedin.com/pulse/shanghai-tower-how-designers-meet-challenges-narendra-shekhawat
If we have a closer look at the core, we can observe that it is not uniform throughout the height. It begins as a square tube consisting of 9 cells, with a total area of 30 square meters. This setting is uniform until the level of zone 4. The shape gets modified by cutting the corners of the square as shown in the picture. From zone 7 and upwards, the shape gets reduced even further into a cross arrangement of 5 cells. In the topmost part of the building, the core system is simplified into a rectangle made of 3 cells.
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The thickness of these walls varies with the height. At the base, each wall is 1.2 meters wide and this width reduces to 0.5 meters at the top zone. In the picture below, we can clearly see the setting of the core system in each zone. b. Outer frame system As introduced above, the outer frame system consists of: 12 super columns, radial outrigger trusses and double belt trusses. The super columns have a cross section of 5.3 m x 3.7 m at the base and it reduces with the height. At the top, their dimensions are 2.4 m x 1.9 m. The corner columns stop at zone 5, while the other eight super columns go up until zone 8. All of the columns incline gradually towards the center as the height increases. This enables the desired slenderness of the structure.
9. Façade concept
The façade of the Shanghai Tower is one of the most interesting features of this structure. It gives it the spiral iconic shape and form, but also makes the tower sustainable and eco-friendly, which is an important feature of this building. The façade is made of a double curtain wall system. The outer skin is cam-shaped in plan. This shape is what gives the building its rotational effect, while the inner skin is circular. Both of them are made out of glass, while a support system was constructed to carry the weight of the outer façade (skin). This support system comprises of tube elements and horizontal trusses. The main element is a horizontal camshaped ring that rotates around the inner skin. This ring is held away from the inner skin, by horizontal trusses that change the position depending on the shape needed for the section. The radius of the ring pipe is 356 mm, while the radial elements have a circumference of 219 mm. Included in this frame there are also vertical steel tube elements with a diameter of 356 mm, which are hung from the upper mechanical floor. In the plan in figure 9.1, we can see the different members of this support system, including the eight expansion joints. An important feature to be noticed is the cross bracing in the three corners of the reduced triangular shape. The inner curtain wall has a regular round shape, outlining the structural plan of the tower and decreasing in its radius with the height. Both curtain walls are supported structurally by the slabs. The space Fig.9.1http://www.ctbuh.org/LinkClick.aspx?fileticket=a1pp between the two façade elements is one of the main DY9UeqM%3D&tabid=1090& 11
attractions of the building: the atriums, which span from one mechanical floor to the other create common areas for each zone that include even green surfaces in the shape of inner gardens. The last idea was a rather important one and was greatly inspired by the Commerzbank building in Frankfurt. According to the final architectural plans, 33% of each floor is green and breathes fresh air into the city’s atmosphere.
One of the most important things to solve during the design of the façade is the type of glass to be used. This is particularly Fig.9.2http://www.gensler.com/uploads/ documents/Shanghai_Tower_Facade_Desig
challenging, because of the energy consumption requirements of n_Process_11_10_2011.pdf the building and also for the implementation of the inner gardens. After major considerations of energy restrictions, climate conditions, but also wind loading effects, most of which were achieved by computational analyses, the final design of the outer skin had a total of 129 915 square meters of glass and about 28 315 panels were used in total. Because of the irregular shape of the tower, 8 different panel shapes were needed, as shown in 9.2. For the inner skin, the individual panels were in regular, rectangle shapes. The type of glass used offers sun shading due to the spectrally selective properties. On the outer façade, fritted glass was also used.
Fig.9.3 Connection details of the outer curtain wall http://www.gensler.com/uploads/documents/Shanghai_Tower_Facade_Design_Process_11_10_2011.pdf
Fig.9.3 Connection details of the inner curtain wall htt : www. ensler.com u loads documents Shan hai Tower Facad e Desi n Process 11 10 2011. d
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10.Sustainable technologies One of the initial goals of Gensler in the design of the Shanghai Tower, was to reach the Gold LEED (Leadership in Energy and Environmental Design) rating. This would be a step forward in sustainable and eco-friendly construction. The principal is that each zone is served by the mechanical floor below, so each one functions independently from the others. The Shanghai Tower has grey water treatment plants incorporated into the basement and podium levels. These plants recycle collected rain water for irrigation and toilet flushing. Also, along the height, there are storage tanks for domestic consumption that uses gravity to modify the water pressure in the needed levels. These kinds of systems reduce the total consumption of water by about 38%. The electrical supply is done by separate units located in the mechanical floors. Even though the limitation of electrical energy consumption for a building of this scale is difficult, it is estimated that the system incorporated into the Shanghai Tower will save about 21.59% in annual cost compared to the baseline indicated by the standards. Also, the parapet of the tower has a twisted shape that is used to collect rainwater. Just underneath the parapet, a turbine is located in order to generate electricity. Air conditioning is achieved through two chiller plants while heating is provided by the same cogeneration plant that is used for the electrical supply. The cogeneration plant itself is a way of reducing costs and recycling energy.
Fig.10.1 http://www.arch2o.com/case-study-bim-implementation-in-shanghai-tower/arch2o-shanghaitower-gensler-04/
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All the materials used in the construction of the Shanghai Tower were obtained within an 800 km radius. This was an important policy, as it decreased environmental impact, but also transportation costs. The double skin façade is also an environmental friendly solution. With this kind of façade, the building acts as a thermos bottle: it preserves daylight, so there is no need for artificial light in the functional areas, it preserves heat, so it reduces costs and the needs for heating and also works as an insulation barrier between the living areas and the outside.
11.Elevators The Shanghai Tower is innovative in this aspect as well. It has the world’s fastest elevator. It reaches
a speed of about 18 meters per second. In total, there are 106 elevators in the structure, including a recordholding 578.5 meters high elevator. All the vertical transportation systems were provided and installed by Mitsubishi. They are energy efficient as well, their incorporated converter systems save up to 30% of electrical energy. http://www.arch2o.com/case-study-bim-implementation-inshan hai-tower arch2o-shan haitower- ensler-04
12.Building Erection The construction of the Shanghai Tower began in November 2008 and was completed in September 2015. Following, there is a chronological list of the construction progress.
Fig.12.1 http://www.gensleron.com/cities/2010/7/15/shanghai-tower-construction-update.html
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Fig.12.2 http://www.gensleron.com/cities/2010/7/15/shanghai-tower-construction-update.html
Fig.12.3 http://www.gensleron.com/cities/2010/7/15/shanghai-tower-construction-update.html
The three pictures above show the process of foundation construction. In the first picture it is clearly visible the area where the mat foundation is being built, but also there is already a clear outline of the core reinforcement extruding from the foundation. The second picture is a close-up, showing the process of concrete-pouring over the already placed reinforcement. The mat slab is 6 meters thick and the concrete was poured in a continuous manner over an uninterrupted 60-hour interval. It required 120 15
concrete trucks per hour, which poured 1 000 cubic meters of concrete per hour and about 61 000 cubic meters in total. It is reported that a number of about 2 000 workers worked in double shifts to complete the foundation in time and succeeded flawlessly. In the last picture there can be seen the building pit and the slurry wall. Since the water table level was too high, it was necessary to build one in order to make the building pit. The wall we see above is a temporary one, while the second and permanent wall, enclosing the building’s perimeter is yet to be built.
Figure 12.4 shows the first meters of the bu ilding’s erection. It is clearly visible the core, also the steelwork for the flooring system. On each side of the core there are cranes which eventually move up as the building progresses. There can also be seen the steel encasing for a super-column. Figure 12.5 is the Shanghai Tower as seen from the Jin Mao Tower in April 2011. It shows the process of slip forming of the core. They used a single formwork for the core and it was moved vertically as the building progressed. In figure 12.6, it is noticeable the magnitude of this project. The small red roofed structures in the left are on-site housing for construction workers. Moving on to figure 12.7, we can notice two super-columns being constructed, but also the steel beams with the duct openings for installations. Another interesting detail about this image are the bamboo scaffoldings, which are still a standard in China. In figure 12.9 and 12.9 there are clearly visible the trusses which support the façade of the tower. On average, they are about 12 meters deep and create spaces up to 20 meters. In figure 12.10, the nearly complete structure can be seen and the zonal division as well, with the mechanical floors clearly visible. In the first zone, the framework support for the outer skin is already installed. In the figures 12.11, 12.12, 12.13, is shown the installation of the outer curtain wall, including some details from the inside of the building. We can notice that the installation of this part of the façade is done simultaneously with the construction of the structure, in order to optimize time.
Fig.12.4 http://www.gensleron.com/cities/2011/5/25/construction-update-shanghai-tower.html
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Fig.12.5 http://www.gensleron.com/cities/2011/5/25/construction-update-shanghai-tower.html
Fig.12.6 http://www.gensleron.com/cities/2011/5/25/construction-update-shanghai-tower.html
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Fig.12.7 http://www.gensleron.com/cities/2011/5/25/construction-update-shanghai-tower.html
Fig.12.8 http://www.gensleron.com/cities/2011/7/18/shanghai-tower-sustainable-strategies-in-asuper-tall-buildi.html
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Fig.12.9 http://www.gensleron.com/cities/2011/7/18/shanghai-tower-sustainable-strategies-ina-super-tall-buildi.html
Fig.12.10 http://www.gensleron.com/cities/2012/9/4/the-new-urbanplanning-look-upward-not-outward.html
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Fig. 12.11
Fig. 12.12
Fig. 12.13
http://www.gensleron.com/cities/2012/11 /27/shanghai-tower-the-curtain-wall.html
Fig.12.14 http://www.gensleron.com/cities/2014/9/4/shanghai-tower-counteracting-the-swayinherent-to-supertall.html
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Fig.12.15 http://www.gensleron.com/cities/2014/9/4/shanghai-tower-counteracting-the-swayinherent-to-supertall.html
The two pictures above are taken in one of the last phases of the structural building process, construction of the crown and the “jewel” that is of course the double damping system, consisting of the
Tuned Mass Damper and the Eddy Current Damper. This whole system is expected to reduce the displacements roughly 20-40 percent. Figure 12.12 shows the shaft where this system will be placed.
Fig.12.16 http://www.dailymail.co.uk/news/article-2714953/Touching-sky-Builders-celebrate-placing-truss-China-s-tallest-building121-storey-Shanghai-Tower.html
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Fig.12.18 http://www.gensleron.com/cities/2015/2/2/shanghaitower-update-lighting-the-building-and-preparing-it.html
Fig.12.17http://www.gensleron.com/cities/2015/2/2/sh anghai-tower-update-lighting-the-building-and-preparingit.html
Fig.12.19 http://www.gensler.com/projects/shanghai-tower
Pictures showing the Shanghai Tower in its finished and final state.
13.Steel As a composite building, steel is a crucial component of the Shanghai Tower. It is used in the composite super columns, floors, core walls, outrigger and belt trusses but also in the support of the façade. So, there were used several types of profiles and different connection methods as well. Bao Steel Group, a Hong Kong-based company was the steel supplier for this project. It provided the high strength structural steel used in different elements. In figure 13.1, there can be seen just a few of the steel elements used, steel beams for the floors in a double T section with side openings for the installations and rebar as well used on the reinforced concrete shear walls, columns and the composite slabs. The slabs have a thickness of 155 mm, 75 mm of which are the steel sheets of 345 MPa strength. Figure 13.2 shows a stripped down version of the tower’s structure, where only the steel elements
are showing. It also shows the connection between these elements. So, the connection between the core
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and the outer super columns is realized using outrigger trusses made of 325 MPa steel, which are connected to the columns using gusset plates and welding. Picture 13.3 shows in detail a connection between the super column and the outrigger truss. The gusset plate design should be designed in a way that guarantees the anchorage of the three steel profiles (in this case) and resists the tension and compression coming from the outrigger truss members. 3D analysis shows the stress state in different parts of the structure and how it is below the critical value of 400 MPa. For the design of the structure in general, but also for the steel and composite elements a finite elements analysis was implemented using Abaqus software. The steel stress-strain relation was adopted from a model which assumes the plastic modulus to be 1/100 the elastic modulus.
Fig.13.1
http://www.skyscrapercity.com/showthread.php?t=391698&page=390
Fig.13.2 http://faculty.arch.tamu.edu/media/cms_page_media/4433/presentationcase%20study%20of%20Shanghai%20Tower%2012-04-14.pdf
Fig.13.3 http://faculty.arch.tamu.edu/media/cms_page_media/ 4433/presentation-
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The Bauschinger effect was as well considered in the computational model and also seismic effects were simulated and studied as one of the main concerns of the structural analysis, considering the location of the building and the soil condition. In figure 13.2, it is also visible one of the eight two-story high belt trusses that form the mechanical floors. To connect these trusses into a single belt, bolt and plate connections were used. Picture 13.4 shows a connection detail. It is noticeable the large number of bolts used. That is a clear hint of the magnitude of internal forces that exist in these elements.
Fig.13.4 http://faculty.arch.tamu.edu/media/cms_page_media/4433/present ation-case%20study%20of%20Shanghai%20Tower%2012-04-14.pdf
Steel was also an important element in the façade design and construction. Both facades are supported by steel frames, consisting of hollow tubes of different diameters. Figure 13.5 is a drawing of the outer skin support system, showing all the elements. The ring beams are set every 4.3 to 4.5 meters and consist of 219x13 and 273x13 profiles. These are the main supporters of gravity and wind load. The link between this structure and the inner core is done by radial struts of cross sections 219x13 and 273x13. These struts are not uniform in their length in order to give the façade its “twist”. The connection of the ring beams to the trusses is
rigid, but the trusses connect to the slabs in a hinge model. This is designed to enable the outer skin to move up and down un-related to the floors. This whole system is hanged on the mechanical floor above via high strength rods. At three corners of the reduced triangle shape, there are cross bracings to resist to the torsional effects. Fig.13.6
Fig.13.5 http://global.ctbuh.org/resources/papers/downloa d/2210-curtain-wall-system-design.pdf
http://inhabitat. com/recentlycompletedshanghai-towerofficiallybecomes-theworlds-secondtallestbuilding/shangh ai-towergensler-5-2/
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Composite columns As mentioned before, composite columns are an integral part of Shanghai Tower’s design. They have been referred to as super columns, because of their dimensions and load bearing capacities. The super columns’ sections are concrete encased. The steel profile is made out of three double T sections connected with two additional plates that ensure that the section works as one. This design was inevitable considering the large dimensions of these members, but economic conditions were also taken into consideration. Composite columns are now becoming a standard in high-rise Fig.13.6 structures, as they combine the best properties of http://faculty.arch.tamu.edu/media/cms_page_media /4433/presentationsteel and concrete, lighten the weight of the structure and lower the costs. Composite members are also efficient in terms of time, as different stories can be built simultaneously. For example, if a group of workers are working with the concrete encasement on one floor, another group could continue with the steel work in the upper. This saves time and costs. Figure 13.6 shows the cross section of a super column in the Shanghai Tower in the first 6 zones and in the last top zones, while figure 13.7 shows the composition of these members. We can notice an important decrease in dimensions. This is due to the fact that upper floors have lower loads, but also to resist buckling effects. The initial dimensions are 5.3 m x 3.7 m and they decrease to 2.4 m x 1.9 m. A clear list of the dimensions for each zone is given in figure Fig.13.7 http://www.sciencedirect.com/science/article/pii/S2214398X15300017 13.7. In the picture we can also see the rebar used. To construct these elements was used high strength steel and concrete of class C50-C70. Because of the large dimensions, the connection between steel and concrete was difficult to achieve and shear failure was a clear risk. For this purpose, the steel profiles of the columns have shear studs welded in them. These shear studs work in a similar way as they do in beams or composite slabs.
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Fig.13.7 http://images.adsttc.com/media/images/56da/0819/e58e/ce77/ee00/0001/slideshow/HIPSH_ShanghaiTo werBook_ZhonghaiShen_pg52.jpg?1457129488
Cranes
During the construction process, a large number of cranes were used, but the most important ones were the four cranes that accompanied the concrete slip form during the construction of the core. This was a innovative solution as it was the first time four different cranes were used for this purpose.
Fig.13.8 http://www.gensleron.com/cities/2014/4/1/sh anghai-tower-the-cranes-come-down.html
14.Concrete The concrete used in the Shanghai Tower varies from a C70 strength in zone 1, 2 and 3 columns, in a C60 strength in all shear walls and columns in zone 4-6 to a final C50 for the columns of the two upper
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zones. This change of concrete class is logical considering the loading decreases as the height goes up. The table below shows a summarization of the concrete elements and also their dimensions.
Fig.14.7 http://global.ctbuh.org/resources/papers/download/833-elasto-plastic-time-history-analysis-of-the-shanghai-tower-underrare-earthquakes.pdf
A similar procedure as for the steel elements, using computerized models was also implemented for the concrete elements. Seismic analyses were also of high importance. The picture below shows the stress strain relation of the shear walls in a plasticity-based model during seismic analyses. It assumes two main failure reasons, tensile cracking and crushing due to compression. Fig.14.8 http://global.ctbuh.org/resources/papers/download/833elasto-plastic-time-history-analysis-of-the-shanghai-tower-under-rareearthquakes.pdf
15.Fire Safety
Fire safety is another important issue of the design of high-rise buildings. Although the chances of fires are quite low, the size of these kinds of buildings increases the chances of a long duration fire. If such an event occurs, some structural member are likely to reduce or lose their bearing capacity. This happens o generally to steel in temperatures higher than 600 C, while concrete may crack under such temperatures causing an exposition of the steel profiles. 27
A fire analysis usually takes in consideration a standard office fire with a given parametric formula of temperature in relation to time and also an accident load caused by local fires. Heat transfer analyses were implemented using finite element analyses and computational methods for each structural member individually. The tests showed that composite beams would last at least on more hour than predicted in the codes during a fire and in midspan, the deflection would not be greater than 20 mm. For the shear walls of the core there was only 15 mm of axial displacement after 6 hours of fire which shows excellent fire resistance. This was due mainly to the high thickness of the walls which ensured that the temperature remained relatively low at about 100oC. Similar results were obtained even for the outrigger and belt trusses, showing a fire resistance of 4-6 hours. The table below summarizes the behavior of structural elements of the Shanghai Tower under fire.
Fig.15.1 http://www.sciencedirect.com/science/article/pii/S2214398X15300017
16.Foundation Designing the foundation of the tower was another challenge the engineering team had to face. This is common for super tall buildings, due to large loads from gravitation, wind and seismic activity. What was uncommon for this particular building were the extremely difficult conditions of the soil. The Shanghai Tower lays on nine layers of sand and soft clays that go at least 120 meters deep, which make s the bedrock practically unreachable. The water table level is just 0.5 meters below ground level. The tabl e below shows a soil profile of the ground below the Shanghai Tower.
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Fig.16.1 http://global.ctbuh.org/resources/papers/download/2221-unique-structural-design-aspects.pdf
The foundation of the Shanghai Tower consists of a 6 meter thick reinforced concrete mat, supported by 947 cast-in-place concrete piles, each with a diameter of one meter. The piles vary from 52 to 56 meters in length and go down to 92-1 stratum of silty sand (see fig 16.1). Every pile is grouted at the end in order to increase its bearing capacity. The picture below shows a plan of the piles. It can be seen that the distribution is not uniform, below the core, piles are oriented in a staggered manner and they are 56 meters long. Also underneath the lateral super columns, they have a staggered distribution, while the rest are orthogonal. This was made to withstand the different loadings of the structure.
Fig.16.2
Settlements were also a major concern at this point. The soil profile offers little possibility to uniformly distribute the loads, so concrete fin walls are implemented ate the basement levels to connect the core to the super columns. These fin walls are expected to reduce the settlements 20-30%. Also the distribution of
the piles in the total area plays a huge role in minimizing settlements. After a period of five years, a total of 100-120 mm of settlement is predicted. The fact that loads from the structure come in a non-uniform manner, influenced on the design http://faculty.arch.tamu.edu/media/cms_page_media/4433/presentati on-case%20study%20of%20Shanghai%20Tower%2012-04-14.pdf
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of the mat foundation. It has a variable stiffness, which helps against the buoyancy effects on the lateral sides.
17.Anti-seismic measures The Shanghai Tower, as seen above, is located in a very difficult area in terms of geotechnics and soil composition. The Pudong area of Shanghai has a seismic intensity of 7 according to the Chinese code, but the magnitude of this project was way beyond any code specifications, so a scientific approach was needed to make the design earthquake resistant. First, the structure of the building was designed to take up large hor izontal forces, not only from seismic activity, but wind loads as well, as discussed above. A numerous finite element analyses were done during the design process and the dynamic characteristics were investigated. Figure 17.1 shows the mode shapes of the first six nodes, obtained through numerical analyses, while table 17.2 displays the numerical values of frequency and period for each mode.
Fig.17.1 http://global.ctbuh.org/resources/papers/download/833-elastoplastic-time-history-analysis-of-the-shanghai-tower-under-rare-earthquakes.pdf
Fig.17.2 http://global.ctbuh.org/resources/papers/download/833-elasto-plastic-time-history-analysis-of-the-shanghai-tower-underrare-earthquakes.pdf
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Most studies show that belt, outrigger and radial trusses remain in the elastic stage during loading, which means damage is not expected in these members. Core walls are damaged around the strengthened stories, while the concrete of the super columns remains in the elastic phase, except to the connection parts where damage is observed. Steel in the composite columns remains in the elastic stage as well and no damage is expected. Researchers at the Tongji University in China also made a Shaking Table Model Test with a 13.04 meters high prototype of the tower. The model was put under seismic conditions of earthquakes up to 7.5 intensity. The tests concluded that the Shanghai Tower is able to withstand earthquakes up to 7 with basic, rare and high frequency, but shows signs of damage under a 7.5 intensity, especially in the upper floors. However, all the seismic performance expectations according to the Chinese code were successfully met.
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References o o
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http://www.arch2o.com/case-study-bim-implementation-in-shanghai-tower/ http://www.ctbuh.org/CongressCommittees/LocalSteering/JunXia/tabid/3013/language /en-US/Default.aspx http://www.slideshare.net/SanskritiJindal/shanghai-tower-40930153 http://www.slideshare.net/chitranjanbagh/shanghai-tower-43402833 http://www.gensler.com/uploads/documents/Shanghai_Tower_Facade_Design_Process _11_10_2011.pdf
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https://en.wikipedia.org/wiki/Shanghai_Tower#Construction http://structureandtalents.com/wp-content/uploads/2015/09/Case-study_ShanghaiTower-2.pdf http://www.ctbuh.org/LinkClick.aspx?fileticket=a1ppDY9UeqM%3D&tabid=1090& http://www.slideshare.net/saramesallam/shanghai-tower-elevator-and-escalators http://www.gensleron.com/cities/2010/7/15/shanghai-tower-construction-update.html http://www.gensleron.com/cities/2011/7/1/shanghai-tower-influences-on-design.html http://faculty.arch.tamu.edu/media/cms_page_media/4433/presentationcase%20study%20of%20Shanghai%20Tower%2012-04-14.pdf http://www.sciencedirect.com/science/article/pii/S2214398X15300017 http://global.ctbuh.org/resources/papers/download/2210-curtain-wall-systemdesign.pdf http://global.ctbuh.org/resources/papers/download/2209-making-the-worlds-greenesttall-building.pdf http://global.ctbuh.org/resources/papers/download/2278-shaking-table-model-test-ofshanghai-tower.pdf http://global.ctbuh.org/resources/papers/download/1003-key-technologioes-in-thestructure-of-shanghai-tower.pdf http://global.ctbuh.org/resources/papers/download/833-elasto-plastic-time-historyanalysis-of-the-shanghai-tower-under-rare-earthquakes.pdf http://www.gensler.com/projects/shanghai-tower?l=featured https://skyscrapercenter.com/building/shanghai-tower/56 https://www.thorntontomasetti.com/projects/shanghai_tower/
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