Seismic Fragility Analysis Of Steel Reinforced Concrete Frame With Special-shaped Columns Based On The IDA

Steel reinforced concrete(SRC)structure with special-shaped columns has both the advantages of the SRC structure and the special-shaped columns structure,and makes up for the shortcomings of the ordinary reinforced concrete structure with special-shaped columns,such as low bearing capacity,low axial compression ratio and weak seismic performance.As a result,the application range of the special-shaped column structure is gradually expanded,and the seismic performance evaluation of the SRC structure with special-shaped columns has become a widespread concern for engineers.Seismic fragility analysis of architectural structures is an important part of the performance-based seismic design idea,and the basic principle is to study the probability of different structural damage under the earthquake waves with different intensity.Through the seismic fragility analysis of the structure,the seismic capacity of the structure and its weak links can be understood deeply.Currently incremental dynamic analysis(IDA)is a parameter analysis method with great prospect to calculate the structural response under the earthquake waves with different intensity.Based on the experimental study on a frame consisting of reinforced concrete beams and SRC special-shaped columns under shaking table test,a SRC frame with specialshaped columns is designed,and the seismic fragility analysis of this frame is implemented based on the IDA Method.Specific studies are as follows:According to the model of the SRC frame with special-shaped columns under shaking table test,the finite element analysis model is established for dynamic analysis by the use of OpenSees software,and in terms of structural dynamic characteristics,acceleration response,displacement response and strain response,the calculated results are in agreement with the experimental results,proving the reasonable and feasible of the software for finite analysis of the SRC structure with special-shaped columns.A SRC frame with special-shaped columns is designed and the elastic-plastic analysis model is established in OpenSees;selecting 15 ground motion records from PEER Ground Motion Database,the incremental dynamic analysis of this frame is carried out;meanwhile the seismic fragility curve of the structure is drawn based on the IDA results,and the seismic fragility analysis of the structure is completed.The results show that the seismic fragility curves gradually tend to be gentle from the full operation to the collapse prevention,indicating that the ductility of the structure plays an important role in structural seismic performance after entering the plastic stage.The probability of structure achieving life safety and collapse prevention is only 10.78% and 6.26% under rare earthquakes.