Study On The Selection Of The Fixed End Position At The Bottom Of High-rise Building Structures

In this paper, using the finite element software SATWE, combined with the relevant existing specification mainly on the bottom of high-rise building structural fixed ends of the rational selection of determination conditions for analysis and research, respectively, from the basement floor lateral stiffness and the adjacent upper story lateral stiffness ratio and an engineering example to analyze the fixed end conditions determining the reasonable selection of the main work, the contents are as follows:(1) Through the establishment of separation model and whole model two kinds of structures at the bottom of the lateral stiffness ratio of block effect of fixed end effects, mainly analyses the dynamic characteristics of the fixed end, influence of deformation and stress characteristics.(2) Through the specific engineering example to analyze the influence of fixed end block selection in different position on the structure of high-rise seismic action.Through the analysis and research, the following conclusions can be drawn:(1) The basement floor lateral stiffness and the adjacent upper structure of lateral stiffness ratio of bottom of high-rise building structure fixed end effect is very obvious; with the basic cycle, frame structure and shear wall structure of their overall model and the separation model of gradually increasing horizontal displacement and internal force characteristics of error ratio of lateral stiffness decreases gradually; when the lateral stiffness ratio is less than2, the dynamic characteristics of the structure, the deformation and stress characteristics of error is large; when the ratio of lateral stiffness is greater than the dynamic characteristics, the deformation of the structure internal force characteristics and2smaller error, error rate is below5%;(2) When the structure of high-rise building basement floor lateral stiffness ratio of the lateral and the adjacent upper structure storey stiffness ratio greater than2, select the basement roof as structural fixed ends, the establishment of separation and calculates the model analysis and the establishment of the overall model and computational analysis of the results of error is not too large. But when the lateral stiffness ratio is less than2, the overall modeling of the underground chamber is used as the roof structural fixed ends a significant effect on the calculated results. (3) With the fixed end down, bottom seismic shear structure increases, i.e. seismic action increases. For this project, embedded in the basement engineering steel volume of the smaller and more conducive to seismic, seismic principle based on this embedded method, optimization. In other projects, design personnel should according to the actual situation of project, fixed position to select optimal structure more reasonable. Correct selection of the fixed end of the block is correct, the premise to ensure the safety of the structure calculation, in the structural design, strictly in accordance with the specification on the fixed end requirements.