【正文】 型已經(jīng)被證明可以有效地減小作用于塔樓的整體側(cè)向荷載，故被世界上許多超高層建筑所采用。為了進(jìn)一步減小塔樓風(fēng)荷載，以風(fēng)洞試驗(yàn)結(jié)果為指導(dǎo)，在塔樓某些部分開洞。從建筑上看，（方案 2中）塔樓頂部處的開口把塔頂分成上部塔冠和下 部穹拱兩個(gè)部分，此舉不僅減小了風(fēng)荷載，而且賦予塔樓一個(gè)獨(dú)特的建筑特征。巨柱的最大截面尺寸達(dá) m 左右并加入由鋼板焊接而成的組合鋼柱。在不同的建筑標(biāo)高位置，通過(guò)去掉局部樓面及位于建筑外周的部分結(jié)構(gòu)構(gòu)件形成建筑立面上的 (開口 )“風(fēng)槽”。經(jīng)過(guò)建筑師和結(jié)構(gòu)工程的協(xié)調(diào)配合，風(fēng)槽層被布置于環(huán)帶桁架層之下，這樣環(huán)帶桁架層可采用傳統(tǒng)的（帶斜腹桿的）桁架形式；與空腹桁架相比可節(jié)省建造成本。由于可以利用風(fēng)槽位置的優(yōu)化達(dá)到提高結(jié)構(gòu)效率的目的，風(fēng)槽得到了結(jié)構(gòu)工程師的歡迎，而建筑師則利用風(fēng)槽創(chuàng)造出獨(dú)特的空間和奇妙的景觀。為了減小這一影響，建 7 筑師和結(jié)構(gòu)師相互協(xié)作，將原方案到 91層就停止的部分核心筒墻體延伸到 123 層，從而以最簡(jiǎn)潔的方式保持了核心筒的力學(xué)性能（參見(jiàn)圖 5）。 隨著塔樓高度 增加，塔樓翼緣逐漸錐化收縮，直到與塔樓中軸線在頂部匯聚為一點(diǎn)，形成一個(gè) 61米高的塔冠（參見(jiàn)圖 6）。桁架支承弦桿采用最大直徑 500mm的鋼管，而桁架腹桿和斜桿選用小尺寸的鋼管。方案包含全穹拱均勻分布式結(jié)構(gòu)體系、局部集中布置式結(jié)構(gòu)體系、水平支承式結(jié)構(gòu)體系和豎向支承式結(jié)構(gòu)體系。 塔冠和穹拱的結(jié)構(gòu)設(shè)計(jì)與建筑設(shè)計(jì)完美結(jié)合，實(shí)現(xiàn)了流暢的建筑外立面效果，巧妙解決了核心筒墻體、塔冠和穹拱之間的過(guò)渡關(guān)系，同時(shí)實(shí)現(xiàn)了頂層的無(wú)柱大空間，利于游客觀光。 Mark Dantel Thornton Tomasetti Inc. 51 Madison Avenue New York, NY USA 10010 Abstract: Wuhan Greenland Center Main Tower is a 125story, 600+ meter megatower in China. The tower structural system has been developed to harmonize with the architecture as an integrated whole to maximize efficiency and enhance safety. The distinctive floor “slots” help reduce the vortex shedding effect. Slot locations were coordinated to avoid causing structural discontinuities. Above the roof, steel trussed tripod legs rise from tower plan wing tips to seamlessly plete the building for m with a dramatic crown. Design challenges include evaluating building performance under seismic events through PBD and performing Progressive Collapse Analyses to evaluate structural redundancy. Parametric modeling tools were used to reduce cladding costs by maximizing the use of fieldwarped, flatglazed panels rather than costly curved glass panels. Key words: PBD, Performance Based Design, Parametric Modeling, Outrigger, Belt Truss Introuduction The wave of MegaTall building construction in China started with cities along the east coast and is now moving inland. Located in Wuhan, an inland city adjacent to the Yangtze River, the Wuhan Greenland Center Main Tower is a 125story, 600+ meter megatower on track to be the 7th tallest building in the world, a mixeduse skyscraper with offices up through the 69th floor, apartments at the 70th to 89th floors, a hotel from the 91st floor to the top floor and a five (5)story deep basement housing the mechanical spaces plus parking. Located at the tower top, a unique 61mtall tower crown and a 35mtall tower dome highlight the tower’s distinctive personality. 11 The major structural system of Wuhan Greenland Center Main Tower consisting of robust posite walls, giant slightly sloping posite SRC columns and curved belt trusses, is adopted to resist the lateral loads ( wind or seismic ) effectively. The locations and geometry of structural ponents have been carefully optimized to not only provide enough strengths and stiffness but integrate with the architecture seamlessly. Tower Massing to Reduce the Wind Load Like other super tall buildings, the lateral loads, wind and seismic, play the most important role in the structural design of Wuhan Greenland Center Main to China “Code for Seismic Design of Buildings “ (GB 500112020), Wuhan is located in the Seismic Fortification Zone 6, with design ground acceleration specified as under moderate earthquake, which is defined as a earthquake with “10% Exceedance Probability in 50year” or an earthquake with 475year return period. RWDI performed wind tunnel tests to determine the structural wind loads for tower strength and stiffness design. For the strength designs of the tower structure, the 100year wind load and seismic load under frequent earthquake, which is defined as “63% Exceedance Probability in 50year” or an earthquake with 50year return period, shall be bined with gravity load. Unlike most building codes , in which the seismic load case never bines with the wind load case, the frequent earthquake load for this tower needs to be bined with 100year wind load as per “Technical Specification for Concrete Structures of Tall Building “(JGJ 32020). The Table 1 lists the 100year wind load and codebase frequent earthquake load. From Table 1, the base shear and overturning moment under a 100year wind load is much larger than the values under the frequent earthquake load. Architectural massing of the Wuhan Greenland Center Main Tower was developed to optimize both the structural and programmatic performance of the building. Four primary design solutions were implemented to deal with both of these issues: a tapered profile, a dome top, triangular floor plans with rounded soft corners and the vent slots (see Figure 1). Since all of these elements help to minimize the negative effects of wind acting on Supertall buildings, they allowed the quantity of structural materials to be reduced and significantly decreased the construction cost. 12 Table 1. Lateral Load Comparison. Based on wind load data from RWDI, February 2020. Load Case 100Year Wind Frequent Earthquake Load Wind / Seismic Direction Base Shear (kN) Overturning Moment (OTM) (kNm) Base Shear :V ( kN) Overturning Moment (OTM) (kNm) Shear Overturning Moment (OTM) Xdirection 64,956 21,645,051 44,729 12,123,867 Ydirection 62,183 21,528,803 44,775 12,147,109 From a structural per