The Analysis And Design Of Different Structural Transfer Floors

With the acceleration of urbanization, land prices in the center of large and medium cities have been highly valued, which leads to the situation that one building should meet the need of various functions, such as market, apartment and office. To cater for the architectural function, the upper structure differs from the bottom one, and it is considered as a kind of complicated design of high-rise structures. The upper bearing members can’t extend continuously to the ground due to the large space demand of commerce and recreation. Proper conversion design should be adopted to transfer the upper load to the foundations.Although structure specifications don’t recommend complicated structures with conversion layer as its’ complex design process. Today’s structure design using conversion layer is common, and the technology of conversion design has obtained considerable development. In addition to the traditional transform methods such as girder converting, truss converting and slab converting, there are other new conversion design methods like inclined columns and braces converting for discontinuous load-bearing structural members. With the update of design software and the accumulation of design experience, structural engineers are not only satisfied with finding a way to solve the problem of discontinuous members, but also focus on how to choose the most optimal transfer methods. The conversion layer should meet the requirements of architectural space design and avoid obvious weak area in the structure at the same time.Based on the engineering case of Jindian building, this paper introduces the general engineering situation and functional requirements which the transfer layer needs to meet. The whole structure model was established in PKPM software with three different types of conversion layers. Further considerations about transfer layers are taken in the process of the whole design. Finite element analysis software such as SATWE、ABAQUS and SAP2000 are used to calculate the stress of transfer members. Then representative parameters of the whole structure are compared to the specification limits, discussing the advantages and disadvantages-of every scheme and giving the recommended solutions as a result. The main parameters of structure include period-ratio, story drift, shear-weight ratio, stiffness ratio and so on. The focuses of parameters are different in every section, but these parameters can reflect the influence of different transfer design on the stiffness and stress distribution of the structure. Push-over analysis is applied for the recommended design, to make a better exploration on the transfer layer damage state under rare earthquakes.This paper analyzed the mechanical characteristics and design process of different kinds of transfer layers, adding representative finite element calculation and stress analysis to different kinds of transfer members. Composite conversion layer design method is proposed and the finite elements design methods of partial conversion members are summarized. The composite conversion design for Jindian building was completed based on the demands of both architecture and structure. The analysis methods and new concept of design idea contained will provide some helpful reference for the arrangement and design of conversion floor.