Study On Seismic Performance Of RC Frame Structure With Basement Considering SSI Effec

Earthquakes can cause huge losses and casualties to humans,and it is urgent to conduct seismic performance analysis of building structures.A large number of experimental studies have shown that soil structure interaction(SSI)has a significant impact on the dynamic characteristics of buildings,leading to an extension of the natural vibration period of the structure,making the natural vibration frequency of the upper structure close to the predominant period of the site,which may lead to co vibration and serious seismic damage to the upper structure.Especially for Class III sites with soft soil,if the SSI effect is not considered,it will lead to a decrease in the reliability of structural seismic risk analysis.At the same time,reinforced concrete(RC)frame structures with basements are widely used due to their strong practicality and other characteristics.Therefore,it is increasingly important to consider the impact of SSI effect on the seismic performance of RC frame structures with basements.This article analyzes the impact of SSI effect on the seismic performance of RC frame structures with basements through finite element software simulation and comparison.This article establishes three finite element models,namely the RC frame structure basement roof embedding,the RC frame structure foundation top surface embedding with basement(without considering soil constraints),and the RC frame structure considering SSI effect of soil embedding around the basement.Firstly,verify the rationality of the three models;Then,modal analysis and dynamic time history analysis of different seismic levels were conducted on three models to explore the influence of SSI effect on parameter selection;Next,conduct incremental dynamic analysis of three models to study the impact of SSI effect on the seismic performance of frame structures with basements from a statistical perspective;Finally,the seismic vulnerability functions of each of the three models were obtained from the incremental dynamic analysis results.Based on the vulnerability curve,the impact of SSI effect on the seismic performance of RC frame structures with basements was evaluated from different perspectives.Based on the selected examples and sites in this article,the main content and relevant conclusions are as follows:(1)Numerical simulation of soil structure interaction system was conducted.Simulate the RC frame structure with basement,raft foundation,and foundation soil through finite element software,and couple them together to lay the foundation for subsequent dynamic analysis.Focus on considering the impact of soil nonlinearity on the upper structure.Due to the inability of ABAQUS software to simultaneously reference two subroutines for calculation,the two UMAT subroutines,PQ fiber for reinforced concrete constitutive law and equivalent linear constitutive law for soil,were compiled together to meet the needs of subsequent calculation and analysis.(2)The rationality of three models was verified,and modal analysis and dynamic time history analysis were conducted under different earthquake levels.Compare and analyze the natural vibration period,interlayer displacement angle,floor acceleration,and column shear force parameters of the three models.After considering the SSI effect,it was found that compared to the other two models,the natural vibration period of the structural system was significantly prolonged,and the inter story displacement angle of each floor increased,but the floor acceleration and central column shear force decreased to varying degrees.(3)Incremental dynamic analysis was conducted on three models to obtain IDA curve clusters.Statistical analysis was conducted to obtain their respective percentile curves,and then the spectral acceleration Sa(T1,5%)of the defined performance points for each model was plotted.After considering the SSI effect,it was found that RC frame structures with basements are more likely to reach the limit state of the structure.Compared to models without considering the SSI effect,the spectral acceleration required to reach the same performance state is smaller.(4)An earthquake vulnerability analysis was conducted.Based on the data results of incremental dynamic analysis in Chapter 4,the seismic vulnerability functions of the three models were obtained,and the probability of structural failure was obtained.This effectively evaluated the impact of SSI effect on the seismic performance of RC frame structures with basements.It was found that the SSI effect can increase the probability of RC frame structures with basements exceeding various limit states.When the SSI effect is considered for the structure,the failure probability of RC frame structures will increase.