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өндөр барилгын бүтээц төлөвлөлт үзэж байгаа оюутнуудад хэрэгтэй байж магадгүй
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өндөр барилгын бүтээц төлөвлөлт үзэж байгаа оюутнуудад хэрэгтэй байж магадгүй

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    өндөр барилгын бүтээц төлөвлөлт үзэж байгаа оюутнуудад хэрэгтэй байж магадгүй өндөр барилгын бүтээц төлөвлөлт үзэж байгаа оюутнуудад хэрэгтэй байж магадгүй Presentation Transcript

    • Introducton to High-Rise Building Structures in China Zhang yanxia zhangyanxia@bucea.edu.cn Beijing University of Civil Engineering and Architecture July 19th,2011
    • Introduction to high-rise building structures in China Outlines Main structural types in high-rise building structures  Intruduction to steel-concrete hybrid structures  Example1:Beijing Fortune Plaza 2 Office Tower Example2: China World Trade Centre 3
    • 1.Main structural types in high-rise building structures (according to different material) Concrete Structures Steel Structures Steel-Concrete Hybrid Structures 3
    • Concrete Structure 1 CITIC Plaza ,Guangzhou ,1996 ,390m 2 Jinmao International Plaza, Shanghai, 2006, 333m 3 Chongqing World Trade Center , Chongqing, 2005, 283m 4
    • Steel Structure 1 Beijing TV Centre, Beijing,2007 ,294m 2 Minsheng Bank Building, Wuhan, 2008, 331m 3 CCTV Tower, Beijing, 2011, 239m 5
    • Phoenix International Media Center Phoenix International Media Center is a multipurpose and comprehensive architecture with functions of television programming, offices and business. As usual, media building has large space such as broadcasting hall, as well as typical office floors vertically. It is hard for this two parts to achieve a harmonious effect. However, in this program, Designers resort to the pattern of Mobius, that is, combines high office floor with media broadcasting hall. While satisfying the need of the place for programming as well as other supporting establishments, it becomes a complete space and volume. Unique building shape combines with the natural scene in Chaoyang Park. 6
    • Phoenix International Media Center 7
    • 2. Introduction of hybrid structure Hybrid structure system composed by steel frame ,steel reinforcement concrete( SRC) frame or concrete filled tube( CFT) frame and RC core tube is a new optional structure system, which is widely used in the design of high-rise buildings, especially the super high-rise buildings, in China nowadays. 8
    • Hybrid Structure 1 Greenland Financial Center, Nanjing, 2010, 450m 2 Shanghai World Financial Center, Shanghai, 2008, 492m 3 China World Trade Center III, Beijing, 2010, 330m 9
    • The main advantages of hybrid structures: Compared with concrete structures •Decrease the structural weight •Reduce the components section •Speed up the progress of construction •Improve the performance of the structures 10
    • The main advantages of hybrid structures: Compared with steel structure Improve the fire proof performance of the structure Decrease the overall cost Increase the lateral stiffness of the structure Improve the comfortable performance under wind load 11
    • 2. Introduction of hybrid structure At present, many high-rise buildings which is about 150m to 200m height or even above 300m height are hybrid structure, but most of those buildings are located in the area of seismic intensity fortification 7( design basic acceleration is 0.10g or 0.15g). According to Chinese building code JGJ3-2002, the maximum application height for hybrid structures is 150m for the area of seismic intensity fortification 8( design basic acceleration is 0.20g). The Beijing Fortune Plaza 2 office tower is 265m tall and will become the second tallest building after the CWTC 3A mega tower in Beijing,, which is in the area of seismic intensity fortification 8, and the tallest CFT frame-RC core wall hybrid structure in Beijing. 12
    • typical buildings of hybrid structure Xuelian Building Xuelian building is a high-rise structure, and is built in high seismic intensity region. It has 36 floors above the ground, and is 146.30m totally high. It s irregular plan and non-orthogonal frame result in weak lateral stiffness. To solve these structural difficulties, the following measures are adopted. The structure is designed as a mixed structure which is composed of concretefilled rectangular steel tube frames and reinforced concrete tubes. Two strengthening stories are designed with outriggers and belt members. 13
    • typical buildings of hybrid structure Xuelian Building in construction 14
    • typical buildings of hybrid structure Connections in Xuelian Building 15
    • typical buildings of hybrid structure CNPC Office Building CNPC Office Building include 4 tower and several podium buildings. Tower is 90m high, has 22 stories above the ground( Tower D is 18 stories),and has 4 stories basement. The podium building is 38.2m high,and has 10 stories above the ground.The standard story height is 3.9m. 16
    • Construction Progress 04.12.8 05.1.1 05.2.1 05.3.1 05.4.2 05.5.2 05.6.2 05.7.2 05.8.5 05.9.2 05.10.2 05.11.8 05.12.8 17
    • Construction Progress 18
    • Construction Progress 19
    • Construction Progress 20
    • typical buildings of hybrid structure Jinmao Tower The building is located on a 24000m² plot of land near the Lujiazui metro station. The 88 floors (93 if the spire floors are counted) are divided into 16 segments, each of which is 1/8 shorter than the 16-storey base. The tower is built around an octagonshaped concrete shear wall core surrounded by 8 exterior composite super columns and 8 exterior steel columns. Three sets of 8 two-story high outrigger trusses connect the columns to the core at six of the floors to provide additional support. 21
    • typical buildings of hybrid structure Shanghai World Finacial Center The building is a supertall skyscraper in Pudong, Shanghai. In order to decrease the weight of the building, the majority of that decrease had to be found in a reduction of the thickness of the concrete shear walls of the services core. This reduction could be achieved only by decreasing the wind and earthquake induced lateral forces resisted by those walls. That decrease could be found only by increasing the stiffness of the lateral force resisting system of the perimeter wall. 22
    • typical buildings of hybrid structure Shanghai World Finacial Center To resist the forces from typhoon (hurricane) winds and earthquakes, three parallel and interacting structural systems were incorporated: 1) The mega-structure, consisting of the major structural columns, the major diagonals, and the belt trusses. 2) The concrete walls of the services core. 3) The interaction between the concrete walls of the services core and the megacolumns, as created by the outrigger trusses. 23
    • Example1 Beijing Fortune Plaza 2 Office Tower 3.1 Introduction : Location : the Center Business District (CBD) Beijing; Height: 256.35m ; Floor : 59 floors and 4 floors underground ; Architectural Area : 150,000m2 Structure System : CFT frame-RC shear wall core 24
    • 3 Beijing Fortune Plaza 2 Office Tower 3.2 DESIGN STANDARDS The design of the proposed development will comply the following current code of practices in China: (1) Unified standard for reliability design of building structures GB50068-2001 (2) General definitions & symbols Architectural Design GB/T50083-97 (3) General definitions & symbols Structural Design GBJ132-90 (4) Specifications for Loading in Building Structure GB50009-2001 (5) Code of Seismic Design of Buildings GB50011-2001 (6) Code for Design of Concrete Structures GB50010-2002 (7) Code for Design of Steel Structures GB50017-2003 (8) Technical Specification for Steel Structure of Tall Buildings JGJ99-98 25
    • 2 Beijing Fortune Plaza 2 Office Tower (9) Technical Specification for Box and Raft Foundation JGJ6-99 for Tall Buildings (10) Specification for Pile Foundation of Buildings JGJ94-94 (11) Beijing Standard – Specifications for Foundation Design DBJ01-501-92 (12) Technical Specification for Tall Reinforced Concrete Buildings JGJ3-2002 (13) Technical Specification for Steel Reinforced Concrete JGJ138-2001 Composite Structures In case where elements are not covered by Chinese Standard, reference to the following standard would be made. (1) Prestandard and Commentary for the Seismic Rehabilitation FEMA356 of Building (2) Seismic Evaluation and Retrofit of Concrete Buildings ATC40 26
    • 2 Beijing Fortune Plaza 2 Office Tower 2.3 MATERIAL DATA 2.3.1 Concrete Grade of concrete for structural components must not less than C30, according to GB50010-2002. Design parameters are as follows: Concrete Grade Standard Value fck (N/mm²) C30 C35 C40 C45 C50 C60 20.1 23.4 26.8 29.6 32.4 38.5 Design Value, fc (N/mm²) 14.3 16.7 19.1 21.1 23.1 27.5 Young’s Modulus Ec (N/mm²) 3.00×104 3.15×104 3.25×104 3.35×104 3.45×104 3.6×104 27
    • 3 Beijing Fortune Plaza 2 Office Tower 3.3.2 Reinforcement All reinforcement complies with Chinese Standard GB50010-2002. Type dia (mm) Standard Value fyk (N/mm2) DesignValue fy , fy’ (N/mm2) Young’s Modulus Es (N/mm2) HPB235 HRB335 8~20 6~50 235 335 210/210 300/300 2.1×105 2.0×105 HRB400 6~50 400 360/360 2.0×105 28
    • 2 Beijing Fortune Plaza 2 Office Tower 2.3.3 Structural Steel All structural steel would be either British Standard Grade 43/Grade 50 or Chinese Standard Q235/Q345. 29
    • 2 Beijing Fortune Plaza 2 Office Tower 30
    • 3 Beijing Fortune Plaza 2 Office Tower 3.4 LOADS 3.4.1 Floor Loads The following live and superimposed loads based on the Chinese Code GB50009-2001 are used. Standard loads of the Fortune Plaza 2 office tower (kN/m²) Location / Type of Loading Roof Live load 1.5 or actual load E&M Finishes 1.5 4.8 – 1.0 Typical Office Floor 3.0 0.5 1.7* Typical Hotel Floor 2.0 0.3 1.2 Staircase 3.0 – 1.2 Mechanical room Refuge Floor * ceiling = 0.5, finishes = 1.2 Not less than 7.5 or actual load 5.0 Partitions – According to framing plan – 1.2 – 1.2 – 31
    • 3 Beijing Fortune Plaza 2 Office Tower 3.4.2 wind loads The wind loads based on the Chinese Code GB50009-2001. Based on 100 years return period, Design wind Load is 0.50kN/m². Wind loads and acceleration for the engineering are still being expected from wind tunnel tests conducted by BMT company. The result of test is similar with the calculation of Chinese Code GB500092001. Wind tunnel test 3.4.3 Snow loads Based on 100 years return period, Design Snow Load is 0.45kN/m². 32
    • 3 Beijing Fortune Plaza 2 Office Tower 3.4.4 Earthquake Loads The data below is based on Chinese Code GB50011-2001 and the recommendations from the “Seismic Hazard Assessment Report ” provided in June, 2008. The Site Category and Seismic Intensity fortification are based on Chinese Code GB50011-2001. •Seismic intensity fortification: Degree 8 Design basic acceleration = 0.20g •Site Category: Category II, Group 1, Tg = 0.37s •Period reduce modulus:0.9; •Structural damping ratio:0.04(frequent earthquake),0.04(design earthquake),0.05(rare earthquake); 33
    • 3 Beijing Fortune Plaza 2 Office Tower 34
    • 3 Beijing Fortune Plaza 2 Office Tower 3.5 Comparison with Code Limits Requirement in Chinese Building Codes Structure System Story Tower Basement CFT Frame - RC Core Tube 59 4 Tower 256.35m(part 7.3m above the roof) Basement Height (m) Note JGJ3-2002 Table 11.1.2 : the maximal application height for Unsatisfied hybrid structures is 150m for the area of seismic intensity 8 18.5 Dimension of Standard Floor Plan (Length×Width, m) Structure Height to Width Ratio 64.33×41.85 256.35/41.85 =6.13 JGJ 3-2002 Table11.1.3:the value should less than 6 Unsatisfied 35
    • 3 Beijing Fortune Plaza 2 Office Tower Torsion Irregularity Horizontal Irregularity Geometric Irregularity Diaphragm Discontinuity Irregularity Y-Direction: all less than 1.2; X-Direction: part beyond 1.2 , but less than 1.3,others less than 1.2 JGJ 3-2002§4.3.5:for the Class B structure, the torsion displacement Mainly ratio should less than 1.2, must less Satisfied than 1.4, when accidental torsion effect is considered. — JGJ3-2002§4.3.6:reduced floor width should less than 50% of the total width.GB50011-2001§3.4.2: Satisfied reduced floor width should less than 30% of the total width in one side. — GB50011-2001§3.4:floor effective width less than 50% of the total width, the open area of floor should Satisfied less than 30% of the total area, and no out-of-plan offset exist. 36
    • 3 Beijing Fortune Plaza 2 Office Tower Stiffness mutation exist at the stories adjoin to the Stiffness Soft strengthen story , but still Story Irregularity satisfy with the code requirement. Vertical Discontinuity in Irregularity Vertical Lateral Weak Story Irregularity GB50011-2001§3.4.2: story lateral stiffness should not less than 70% of the stiffness of the Satisfied upper story, and 80% of the average stiffness of the upper 3 stories. GB50011-2001§3.4.2: vertical Discontinuity in vertical lateral force should not be transferred by Satisfied not exist horizontal members. JGJ3-2002§4.4.3:for the Class B Bearing Capacity mutation structure, the story shear bearing exist for the strengthen stories capacity should not less than exist. 75% of the capacity of the upper story. Story Shear to Weight Ratio Minimum Value : 0.024 JGJ3-2002§3.3.13:to structure whose fundamental period beyond 5s,the minimum value is 0.024 Satisfied 37
    • 3 Beijing Fortune Plaza 2 Office Tower 3.6 Floor Diaphragm •Profiled steel sheeting-concrete composite slabs •Steel beam connected with RC slab by shear resisting stud •C40 concrete is used •Thickness: a.130mm for office stories(requirement of comfortable) 200mm for mechanical stories/strengthen stories(the result of elastic calculation) b.200mm for the 1st bottom floor(requirement of embed) c.200mm for the roof, 130mm for the concrete floor in the core tube. 38
    • 3 Beijing Fortune Plaza 2 Office Tower 3.7 Lateral Resisting System—Core Tube 39
    • 3 Beijing Fortune Plaza 2 Office Tower 3.7 Lateral Resisting System—Core Tube •Dimension: 42.3m×15.9m(Footing-44th Story),34.8m×15.1m(45th Story-Roof) •Thickness: Decrease smoothly from 1200mm to 600mm with story increasing •The core tube resists most of the gravity and lateral force, and shows a great torsion resisting capacity. 40
    • 3 Beijing Fortune Plaza 2 Office Tower 3.7 Lateral Resisting System—Core Tube According to the Chinese Building Codes, the seismic resisting level of the core tube is special 1st ,so the bottom ,1st Story to 16th Story, should be strengthen. Composite steel plate shear wall(CSPSW) is used to increase the ultimate bearing capacity and the ductility of the core tube. 41
    • 3Beijing Fortune Plaza 2 Office Tower 3.7 Lateral Resisting System—Core Tube The core tube should satisfy with the requirement of keeping elastic under precautionary seismic intensity. Ratio of axial compression stress to strength should be controlled strictly 42
    • 3 Beijing Fortune Plaza 2 Office Tower 3.7 Lateral Resisting System—Core Tube The section of hidden beam and hidden column around CSPSW should be increased, so that the hidden beam and column can constrain the steel plate effectively to make full use of the steel plate. Hidden column should be settled at the corner of the core tube, and connected with the hidden beam. 43
    • 3 Beijing Fortune Plaza 2 Office Tower 3.7 Lateral Resisting System—Core Tube Advantage of CSPSW a.Reduce the weight of core wall and seismic response b.Reduce the needs of the pipes under the core wall and the settlement of subsoil c.Reduce the ratio of axial compression stress to strength of the bottom wall d.Increase the capacity of the core wall e.Increase the performance of the structure under the rare earthquake, delay the appearance of the plastic hinge and increase the stability of the hole structure. 44
    • 3 Beijing Fortune Plaza 2 Office Tower 3.7 Lateral Resisting System—Core Tube Disadvantage of CSPSW a.Increase the cost b.Hard to construct c.Increase the requirement of professional and equipment 45
    • 3 Beijing Fortune Plaza 2 Office Tower 3.8 Outriggers Single storey steel outriggers are introduced at Level 26A , Level41A and top level within the double storey height belt truss to mobilize the lateral resistance of the perimeter frame through push-pull action of perimeter columns straddling the connection between the outrigger and belt truss. The use of an outrigger increases the core’s rotational resistance by placing a restoring moment into the core and hence reduces the lateral deflection. The outriggers connect to belt trusses on respective levels so that the columns on both sides of each outrigger could be mobilized for the push-pull action. Since the mobilized columns are not at corner, the shear-lag effect is diminished to a large degrees. 46
    • 3 Beijing Fortune Plaza 2 Office Tower L11A belt trusses L26 A,L41A outrigger 47
    • 2 Beijing Fortune Plaza 2 Office Tower 48
    • 3 Beijing Fortune Plaza 2 Office Tower 3.9 Perimeter Frame Dimension: 64m×41.5m,Perimeter columns are spaced at 6m All the perimeter columns are used as part of the building lateral resisting system. Perimeter beams are steel beam, and the beam to column connection are rigid. 49
    • According to Chinese Building Codes, the base shear resisted by perimeter frame must not less than the maximum value of 20% of the total force and 1.5 times the maximum of story shear force. In fact, the criteria reflect the objective needs of arranging the perimeter frame reasonable. Only the perimeter frame has a proper stiffness can the design satisfy with the criteria. 50
    • 3 Beijing Fortune Plaza 2 Office Tower Introduction of concrete filled tube(CFT) column In addition to high strength 、 light quantity 、 good shape 、 fast tiredness and fast strike, the concrete-filled steel tubular structures have a lot of advantages, such as simple node form 、 flexible construct layout 、 big section inertial rules 、 good stability 、 convenient construction and easy fireproofing measure and so on 51
    • 3Beijing Fortune Plaza 2 Office Tower Compare of SRC and CFT Both of SRC and CFT members are so called composite members, and are widely used in super high-rise buildings as column of perimeter column. The composite members have better capacity and ductility, so smaller section can be selected by using the composite members. Compared with SRC members, CFT members need not be limited the ratio of axial compression stress to strength, and better capacity to resist bending. Hence, the CFT column has the advantage in super high-rise building design. 52
    • 3 Beijing Fortune Plaza 2 Office Tower 3.10 elastic analysis Analyse result and FEA method model SATWE ETABS 53
    • 2 Beijing Fortune Plaza 2 Office Tower Period and mode of vibration Mode of vibration SATWE ETABS 1 5.496 5.530 2 4.798 4.833 3 3.299 3.603 4 1.547 1.589 5 1.347 1.364 6 1.049 1.137 54
    • Mode 1 (X direction moving) Mode 2 ( Y direction moving ) Mode 3 ( Torsion ) 55
    • 2 Beijing Fortune Plaza 2 Office Tower Base shear and overturning moment SATWE calculation result Earthquake Earthquake load - direction load - direction X y Wind load – direction x Wind load – direction y Base shear(KN) 54068 55336 30690 20182 Overturning moment ( M N.m ) 7906 8948 4732 3114 ETABS calculation result Earthquake Earthquake Wind load – load - direction load - direction direction x X y Wind load – direction y Base shear(KN) 52295 53641 31282 20889 Overturning moment ( M N.m ) 8105 9064 4947 3150 56
    • 3 Beijing Fortune Plaza 2 Office Tower The story shear force under horizontal load (SATWE) 57
    • 3 Beijing Fortune Plaza 2 Office Tower The ratio of Story shear to gravity under horizontal earthquake load (SATWE&ETABS) 58
    • 3 Beijing Fortune Plaza 2 Office Tower The calculated result shows that the ratio of story shear to gravity using two software are similar, and satisfies with Chinese code demand that the minimum ratio of story shear and gravity should be bigger than 2.4% basically. 59
    • 3 Beijing Fortune Plaza 2 Office Tower Interstory drift under horizontal earthquake load and wind load SATWE Max ratio of interstory drift Max horizontal Drift of top story ( mm ) ETABS Max ratio of interstory drift Max horizontal Drift of top story ( mm ) Earthquake load - direction X Earthquake load - direction y Wind load – direction x Wind load – direction y 1/556 1/726 1/1025 1/2177 345 263 196 89 Earthquake load - direction X Earthquake load - direction y Wind load – direction x Wind load – direction y 1/560 1/737 1/852 1/1587 337 264 201 99 60
    • Interstory drift under horizontal earthquake load and wind load (SATWE) 61
    • 3 Beijing Fortune Plaza 2 Office Tower 3.11 Elastic/Elasto-plastic time-history analysis 3.11.1 compare of time-history method, equivalent base shear method and response spectrum method Main distinction between time-history method and response spectrum method is: Design response spectrum in response spectrum method responses intension of ground motion and behavior of average frequency spectrum ,but time-history method responses roundly intension of ground motion,behavior of spectrum and duration time; 62
    • 3 Beijing Fortune Plaza 2 Office Tower Response spectrum method based on elasticity assume, but time-history method directly considers construction members and structure elasticoplasticity behavior, can find out exactly frail link of structure, so that control structure elastico-plasticity response under the Rare Earthquake, prevent building collapse; Response spectrum method only analyses maximum earthquake response, but time-history method can provide time-history curve, so find out order of plasticity hinge in construction members, estimates structure destroy theory. 63
    • 3 Beijing Fortune Plaza 2 Office Tower 3.11.2 Choose and scale ground motion record Intension of ground motion; Spectral characteristics; Duration time 64
    • Spectral characteristics of picked ground motions; 65
    • Intension of ground motion; Duration time 66
    • 3 Beijing Fortune Plaza 2 Office Tower 3.11.3 Result of time-history analysis 67
    • 3 Beijing Fortune Plaza 2 Office Tower 68
    • 3 Beijing Fortune Plaza 2 Office Tower 3.11.4 Study of outriggers in top 70 60 St or y 50 40 no t op out r i gger 4 pai r 900* 550* 40* 40 3 pai r 900* 550* 40* 40 2 pai r 900* 550* 40* 80 30 20 10 0 0 0. 0005 0. 001 0. 0015 St or y D i f t r 0. 002 69
    • 3 Beijing Fortune Plaza 2 Office Tower 3.11.5 Elastico-plasticity analysis and design recommendation under the Rare Earthquake 70
    • 71
    • 4.Example 2 China World Trade Centre Phase 3 4.1 Outline of the Project China World Trade Centre Phase 3 is located in the Central Business District (CBD) Beijing. The site is surround by the East 3 Ring Road on the east, China Grand Hotel in the south and Kerry Centre on the north. China World Trade Centre Phase 3A includes: (1) A 330m tall mega tower (2) A ball room (3) A retail block The whole phase 3 will be linked together by means of a basement. Basement level 1 will be used for retails.
    • 4.2 、 The Mega Tower
    • The Mega Tower is 330m tall at its highest level, which is a helipad. The elevation of main roof is 316.60m. There are totally 73 stories above ground, in which 1/F to 4/F are for atrium and multipurpose,5/F to 56/F are office levels, and above 56/F are for hotel. There are 3 underground levels, B3 is for parking and MEP, while B2 and B1 re reserved for MEP and commercial space.
    • 4.3 STRUCTURAL SYSTEM – MEGA TOWER 4.3.1 、 Description The Mega Tower forms part of the China World Centre Phase 3 development and consist of the following : • Total structural height is 316.6m. • These are 73 levels above ground comprising of office, hotel and restaurant usage and 4 levels of basement. • A 20m tall façade roof feature above mechanical floor levels encloses a rooftop helipad. • Above L73 there are steel structures to support the helipad at 330m high, surrounded by facade structure
    • 4.3.2 、 Lateral Stability System The lateral stability of the Mega Tower employs a tube-in-tube structure provided by a perimeter composite moment frame, a braced composite central core frame, and outriggers as a means of linkage between them.
    • 4.3.3 、 Perimeter Moment Frame The layout of the perimeter frame basically follows the floor plan of the building, being a chamfered square shape in plan. The overall dimension of the tube varies from around 55.3m at ground level, to 44m at L73. The centre to centre distance of columns of the perimeter frame is 5.6m for hotel levels, but reducing to 4.2m for all other levels (excluding belt trusses and bottom levels), maximising the tube action of the perimeter frame.
    • 4.2 、 Outriggers Single storey steel outriggers (see Fig. 7.3) are introduced between Level 28-29 and level 56-57 within the double storey height belt truss to mobilize the lateral resistance of the perimeter frame through push-pull action of perimeter columns straddling the connection between the outrigger and belt truss. The use of an outrigger increases the core’s rotational resistance by placing a restoring moment into the core and hence reduces the lateral deflection. The outriggers connect to belt trusses on respective levels so that the columns on both sides of each outrigger could be mobilised for the push-pull action. Since the mobilized columns are not at corner, the shear-lag effect is diminished to a large degrees.
    • 4.3 Central Core The overall dimension is about 26.8m x 20.7m from pile cap to L33, 23.8m x 20.7 from L33 to L57 and 20m x 20m above L57. The core frames, which are shown in Fig. 7.4 as elevation 1-10, is braced frame composedof steel reinforced concrete (SRC) columns, steel beams and steel braces. The SRC columns are L-shaped or rectangular with 2 to 7 steel sections cast in. Steel beams and braces will be connected to steel sections in SRC columns directly.