| A growing number of irregular structures appear with various functions of buildings with the rapid development of modern society.One of the typical representative is the structure with a big opening hole in the middle of the floor.The cost of concrete structures and their foundations improve a lot as the increasing height of buildings,and the comprehensive advantages of steel frame structure make it widely used.Be widely known,the damage of the steel frame structure is very complex under the earthquake.Floor with big opening holes lead to the stiffness weakening of steel frame structure and make structural design more complex.Combined with the engineering example,a detailed analysis about the overall performance of steel frame with big opening holes in the floor is conducted in the in the dissertation,in order to provide reference for this type of structural design.A typical steel frame structure with big opening holes in the floor is selected from a 8 degree seismic intensity area and its floor opening rate has reached 32%.The finite element software ETABS is used to analyze the overall performance of the structure.The research contents and conclusions are listed as follows:(1)The ETABS software is used to establish the finite element model of the original steel frame structure with big holes in the floor.The dynamic property and displacement response results are obtained under the two sets of structure with rigid floor and elastic floor.The result is obtain that the two sets of floor have little effect on the dynamic characteristics such as natural vibration period,but there is a large deviation of the structure displacement.So in order to get accurate results,the elastic floor should be adopted in structure analysis about the steel frame structure with big opening holes in the floor.(2)The finite element software ETABS is used to calculate the static elasticity of the overall structure model in frequently occurred earthquake.The dynamic property and displacement response of the overall performance of steel frame with large opening holes in floor are obtained by the change of steel column section,girder section and floor thickness,and the reaction rules are obtained.The dynamic response of the structure is decreased with the increase of the steel column,and the strong lateral stiffness axial displacement is restrained;the structure dynamic response is increased with the increase of the section of the steel beam,and the strong lateral stiffness axial displacement is restrained;the dynamic response of the structure is also increased as the slab thickness increases,and the displacement of the weak lateral stiffness axis is restrained.The conclusion is obtained that the increase of the dimension of the member increases the structural stiffness、the structure quality and the structural stress,and the influence on the overall performance of the structure is uncertain.(3)The software ETABS is used to compare the three model results of the original steel frame of big opening holes in floor,the arrangement of buckling restrained braces along the axis and buckling restrained braces along the hole.The overall performance of steel frame with big floor opening holes is improved and the overall deformation of the structure is decreased by the two supporting scheme.The order of the whole torsional vibration mode of the structure is delayed by the buckling restrained braces along the direction of the principal axis,and the overall torsion of the structure is improved effectively,so does the seismic performance of the structure.(4)The ETABS finite element software is used to analysis of the two models,the original steel frame with big opening holes in the floor and the arrangement of buckling restrained braces along the axis steel frame,with the elastic-plastic time history analysis in three actual rare earthquake waves.The two structures’ reaction process of rare earthquake is obtained.Through the analysis,the structure torsion situation is relieved with the axis direction of BRB,and the overall performance of the steel frame with large floor opening holes is improved. |
