Numerical Analysis Of Collapse-resistant Performance Of RC Frames Under Earthquake

In recent years,the study of the collapse-resistant performance of the RC structure under the accidental load such as explosion,impact,fire was studied extensively.However,the seismic action may also lead to failure of support members with damage or initial imperfections,and will exacerbate the dynamic effects of vertical collapse of structures.Therefore,this paper studies the vertical progressive collapse behavior of reinforced concrete frame structures under the action of the failure of frame columns induced by earthquake.(1)Based on the OpenSees nonlinear finite element analysis platform,considering the bond slip effect of reinforcement,the numerical calculation of a restrained beam test is carried out,and the simulation results can effectively express the elastic stage,plastic stage,arch action stage and catenary stage,On the basis of the above,the experimental results of a single-story plane RC frame structure and a three-story plane RC frame structure are simulated and analyzed furtherly.,the numerical results fitted the experimental results well.(2)Choosing the three-story plane RC frame structure as study object,the numerical calculation of collapse-resistance by changing section dimension,the number of spans and the number of stories were carried out,and the influence of the lateral resistant stiffness,number of stories on the plastic and ultimate bearing capacity was analyzed,in addition,the force mechanism analysis of the plane frame structure was discussed.On this basis,the relevant suggestions of collapse-resistant calculation and evaluation were given.(3)Based on OpenSees,eight seismic waves including far-field,near-field and artificial seismic wave were selected.The incremental dynamic analysis method is used to analyze the progressive collapse-resistant performance of a middle-column-removed reinforced concrete frame structure under earthquake.The results show that under the combined action of the horizontal and vertical seismic wave,the experimental framework did not collapse under eight degree rarely occurred earthquake,it has sufficient collapse-resisting capacity and fine aseismic behavior.The results also show that the vertical seismic action will significantly increase the risk of vertical progressive collapse of damaged structures,and the horizontal seismic action can also weaken the collapse-resistant performance of the damaged structure.(4)Based on the calculation model suggested above,the progressive collapse-resistant performance of the planar frame structure with the middle column gradually failed under the eight degree rare earthquake(PGA=0.4g)was analyzed.The results show that the influence of the earthquake on the maximum vertical displacement of the middle column and the maximum tensile strain at the end of beam was gradually reduced with the increase of the failure time,and the influence of the failure time on the peak acceleration and the peak velocity was reduced under the condition of relatively long failure time.