Tall Buildings Beam Type Transfer Layers Structure Design Principle And Its Application

In recent years, the modern high-rise buildings have been built in the direction ofgreater height, more complicated shape and multi-use. The high-rise building withtransfer floor is a typical representative in which different using-demand could be metin the same building. For instance, instead of traditional usage mode, we can definemultiple functions in a building, stores or restaurants for the lower, offices for theintermediate, and residences for the upper. This construction form with decreasingvertical space goes against with requirements of traditional architectural structure.The amount of vertical members gradually increased with addition in the height ofstructure. Therefore, a transfer member was needed in the change place, while thecorresponding story was called transfer story. The common types of transfer floor arebeam, truss, thick slab, box type and lapping column transfer structure. Among them,the girder transfer floor is most widely used in that it gathers the characteristics ofclear-edge, relatively simple calculation process, simple construction and goodeconomic effect etc.The lateral stiffness of irregular high-rise structure with transfer floor structuretends to mutate near the transfer floor, which is harmful to the integral stress,anti-seismic capability and should be considered in the stage of conceptual design.Frame-supported shear wall, bearing column transfer structure，or both, are widelyused in girder transfer floor to realize structural transfer by transfer girder. Due to thearched stress flow from shear wall, the former is subjected to the tensile force besidesheavy bending moment and shear stress, which makes it belong to the eccentrictension members, while the latter still belongs to the flexural members only carryingcomparatively heavy bending moment and shear stress. As the key poiont of structuraldesign of conversion layer, the arrangement of structure determines its endurance andcost. Considering the structure arrangement, what we should focus on is how to dealwith the mutation of lateral stiffness. One of the solutions is to increase the amount ofshear walls linked with the ground when the lateral stiffness fails to meet therequirement of standards. In addition, as a result of its complexity, two differentmechanical models are needed in analysis and computation.As a crucial part of gider transfer design of high-rise building, The transfercomponents design should base on overall analysis. The section design could be go on after finite-element analysis supplemented. Due to the large size and complexity onload, both of transfer beam and framed column should follow the computation rulesand structural specifications in “Technical Specification for Concrete Sstructures ofHigh-rise Building”, then the bearing and seismic capacity of transfer floor memberscould be guaranteed.Combining with the project of Desiqin city square in Changsha, this paper brieflyintroduced engineering situation and design process of5#building of A2plot, andfocused on the selection of transfer floor structure. According to the characteristics of5#building, such common forms as real abdomen beam type conversion, eveninternode open-web truss conversion, box conversion and thick plate conversion werefirst selected. After modeling and calculation with SATWE, taking mechanicalproperties, materials consumption, difficulty level of construction, structural andeconomic performance into account, the real abdomen beam transfer floor was pickedout as conversion form comprehensively.After the transform determined, this paper took ETABS and SATWE twosoftwares into use. Comparative analysis was done on major parameters period ratio,the lateral stiffness ratio, the ratio of interlaminar shear bearing capacity, the ratio ofthe shear and gravity, and the structural stability, then the internal force diagram ofthe transfer girder was drawn out, and a representative bearing column transferstructure was selected for supplementary calculation and analysis. This work gotcertain engineering application experience and tried to theoretically support thedesign of girder transfer floor.