IDA-base Seismic Vulnerability Analysis Of Steel Reinforced Concrete Frame Structure With Special-shaped Columns

Usually the section forms of steel concrete with special-shaped columns are L、T and十.This section overcomes the problems of protruding of the rectangular columns in the common building structure,affecting the appearance and the use area of the building.At the same time,the structure and components have the advantages of SRC structure,high bearing capacity and high seismic capacity.scholars have made pseudo static test and theoretical research on the mechanical performance and seismic performance of SRC with special-shaped columns and frames,but the research on the dynamic performance of this kind of structure is less.Because the experience of actual structure is stochastic and uncertainty of ground motion,use the probability to evaluation the seismic performance of frame steel reinforced concrete with special-shaped column standard,become a future direction,this paper combined with the incremental dynamic analysis method based on probability and vulnerability analysis,based on probability to evaluates the seismic performance of the structure,the specific research results are as follows:First of all,this paper uses OpenSees software to verify the rationality of the finite element simulation of three steel reinforced concrete columns with special-shaped,the three frame have different spatial locations and different types of steel.Base on increment dynamic analysis and vulnerability analysis method,The probability that the structure can maintain the limit value of each state of the structure by input seismic wave of three fortification levels in high intensity region is obtained.At the same time compared two earthquake intensity parameters PGA and S_a（T₁,ξ）to evaluate the effectiveness of the structure.The results showed that:S_a（T₁,ξ）as the earthquake intensity parameter of the structure is more efficient than PGA.Under the same axial compression ratio,the seismic capacity of lattice middle frame is the strongest,solid middle frame is the second,solid edge frame is the weakest.In eight degree seismic fortification intensity region,the probability of three frame meet the requirement of‘reparable under design based earthquake’and‘no collapse under rare earthquake’proposed by code of our country is higher,but meet the requirement of‘perfect under frequent earthquake’is lower.In nine degree seismic fortification intensity region,the probability of the three frames to meet the requirements of the three fortification level is lower.Secondly,on the basis of incremental dynamic analysis,find out the weakest failure mode of the framework,through the Recorder software module records the steel pressure and concrete compression strain of key section of the structural in weakest failure mode;Follow structural failure path under weakest failure mode,puts forward three kinds of reinforcement methods.The results showed that the seismic performance of the three structural that is strengthened is higher than that of the original structure.Among them,the seismic performance is the strongest according to the failure sequence and the failure principle of‘strong column and weak beam’principle.Finally,this paper compares the vulnerability analysis curves of the structure that considering the collapse probability correction through the indirect method and the direct method,then compares the difference of vulnerability analysis curves of the structure that have considering the collapse probability correction with the structure that without considering the collapse probability correction.Compare the vulnerability analysis curves that without considering the collapse probability correction,the fragility curves of taking into account the probability of collapse two revised methods in the frame damage grade is smaller have little differences,in the damage level is large,modified and unmodified fragility curves are bigger different;The fragility curves obtained by the direct correction method and the indirect correction method vary greatly with the increase of seismic strength.