Study On The Effect Of Floor Opening On Seismic Performance Of Frame Structure

Reinforced concrete frame structure can provide large space for use,and it has been widely used in multi-storey houses in China.Due to the demand of the building use,often local open hole was carried out on the floor,floor open hole after the original power transmission path and the reinforcing bar is cut off,around the mouth of the cave floor stiffness weakened,is bound to impact on seismic performance of structure as a whole.Under the current specification,only the floor open hole rate have relatively clear rules,but through the floor open a hole in the earthquake disaster building structure damage research,found that in addition to the floor,open hole rate floor open hole in other forms will be building structure under seismic action are affected.Therefore,the impact of the floor opening on the seismic performance of the frame structure cannot be confined to the research on the opening rate.Based on the previous research,the main tasks of this paper are as follows:(1)With a 4 floor frame structure of the open hole as the background,with opening hole in the floor rate and the floor in the different levels of open hole location within the same structure plane as the research variables,on the basis of floor open hole on the influence mechanism of frame structure set up eight floor different forms of open hole calculation model under different filler wall arrangement calculation model and divided into two groups,after through finite element analysis of floor open hole effect on the overall seismic performance of frame structure.(2)Modal analysis,mode decomposition response spectrum analysis,nonlinear time analysis and static elastoplastic analysis of the first group of 5 models with different opening rates as the study variables were performed.Under the effect of multiple earthquakes,the lateral stiffness of the structure is weakened,and the lateral displacement of the structure is increased,and the negative influence will increase with the increase of opening rate.Under severe earthquake,floor open hole makes structure in elastic-plastic stage of yield mechanism by column hinge type to beam hinge type development,and when open hole rate control in about 20%,the yield mechanism of the whole structure of the ideal.(3)On different floor level of open hole position as the second group of four models of research variables for modal analysis,vibration mode decomposition response spectrum analysis,nonlinear time history analysis and static elastoplastic analysis.In the case of multiple earthquakes,the lateral stiffness of the whole structure will be greatly weakened when the floor is in the middle of the plane.The hole in the structure corner will significantly enhance the torsion effect of the frame structure,and highlight the weakness of the structural corner.Under the action of the earthquake,the position of the opening of the floor is deviated from the center of the structure plane,and the yield mechanism of the whole frame structure will be restrained to the hinge type development.Opening a hole in the plane of the structural plane may cause brittle failure without obvious warning in the earthquake.