Uncertainty Analysis Of Seismic Response Of Frame Structures

A destructive earthquake is a natural disaster that occurs infrequently but has very serious consequences.An important way to mitigate the consequences of earthquake disasters is to improve the seismic performance of engineering structures.The analysis of the seismic performance of structures mainly depends on their seismic response analysis,and the seismic response analysis has great uncertainty due to the complexity of the seismic inputs and the variation of structural parameters.In this paper,reinforced concrete frame and steel structures are selected to study the uncertainty of the seismic response of widely popular frame structures,and Open SEES finite element analysis platform has been used to analyze the effect of various seismic inputs and various structural parameters.Quantitative results of the uncertain distribution are given based on the analysis.The main work of the paper includes the following:(1)For the selection of proper elements in the Open SEES finite element numerical analysis,a four-layer reinforced concrete frame structure is used as the basic analysis model.Nonlinear beam-column fiber elements based on stiffness and nonlinear beams based on flexibility are chosen for the comparison study.Other parameters such as the number of elements,the number of integral control points,and the number of fiber crosssection meshes are also briefly analyzed,with the intention of minimizing the computational work while not affecting the accuracy of the response analysis.(2)Vulnerability and uncertainty analysis of multi-layer reinforced concrete structures:Based on the Open SEES finite element analysis platform,a multi-layer reinforced concrete basic analysis model is established,and a large amount of nonlinear analysis of the structures under seismic action is performed by scaling the selected ground motion records from the PEER NGA database and changing the structural parameters.The structural parameters considered in this study include concrete strength,damping ratio,and eight concrete and steel material parameters.Beta function is selected to represent the uncertainty distribution based on the analysis in this study and the actual loss distribution from more than 20 years of loss data from New Zealand earthquakes.(3)Vulnerability and uncertainty analysis of steel structures:The incremental dynamic analysis(IDA)is selected to study the seismic vulnerability of steel structures.The Open SEES finite element analysis platform is again used to study the influence of different steel types on the seismic performance of steel structures.A 25-layer steel frame structure of the same dimension with and without viscous dampers is used for the comparison study.For both models,peak ground acceleration(PGA)is used as the ground motion strength index,and the maximum inter-story drift of ?max is used as the engineering demand parameter.15 ground motion records is again selected from the PEER NGA database to perform the IDA on two models.A cluster of vulnerability curves are constructed and and Beta function is again selected to represent the uncertainty distribution of the analysis results.The comparison study clearly demonstrated the significant effect of the viscous dampers.