地震动参数与既有RC框架校舍加固前后抗震性能指标相关性分析

Correlation analysis between ground motion parameters and the seismic performance indices of an existing RC frame school building before and after strengthening

多层钢筋混凝土(Reinforced Concrete,RC)框架结构是我国中小学校舍中最常见的结构形式之一,其抗震性能受地震动参数影响较大。文中围绕地震动参数与既有RC框架校舍及其加固后的抗震性能指标相关性展开研究。首先,确定描述地震动特性的关键参数,据此选择了20条具有不同特性的地震动记录。同时,针对某RC框架校舍,设计了包含增大截面、黏贴角钢和黏贴碳纤维布的综合加固方案。随后,建立了加固前后结构有限元模型,开展了结构动力特性分析,并对结构进行了多遇地震下的弹性时程分析和罕遇地震下的弹塑性时程分析。最后,计算了薄弱层层间位移角和残余层间位移角与拟合特征周期、震中距、平均剪切波速和峰值速度/峰值加速度(PGV/PGA)的相关性。研究结果表明:加固后,罕遇地震下结构底层层间位移角平均衰减64.03%,残余层间位移角平均衰减92.05%,结构抗震性能显著提升;薄弱层层间位移角在近场地震罕遇下可达远场地震下的1.90倍;拟合特征周期和PGV/PGA对结构抗震性能指标影响较大,加固前后,层间位移角与拟合特征周期的相关系数分别为0.90和0.82。研究工作可为既有RC框架校舍抗震性能评估和加固设计提供参考.

Multistorey Reinforced Concrete(RC)frame is one of the most common structural forms of China in primary and middle school buildings.Its seismic performance is greatly affected by ground motion parameters.This paper focuses on the correlation between ground motion parameters and seismic performance indexes of existing RC frame school buildings with and without strengthening.Firstly,the key parameters to describe ground motion characteristics were determined,based on which 20 ground motion records with different characteristics are selected.Then,an integrated strengthening scheme,including increasing section,sticking Angle steel and sticking carbon fiber sheeting,is designed for an RC frame school building.Furthermore,the finite element model of the structure before and after strengthening is established,the structure's dynamic characteristics are analyzed,and the elastic time-history analysis under frequent earthquakes and the elastoplastic time-history analysis under rare earthquakes are carried out.Finally,the correlations between the drifts/residual drifts and characteristic fitting period,epicenter distance,average S-wave velocity,and peak velocity/peak acceleration(PGV/PGA)are calculated.The results show that after strengthening,the drift of the bottom story attenuates by 64.03%on average,and the residual drift attenuates by 92.05%on average,so the seismic performance of the structure is improved significantly.The weak story's drift under near-field earthquakes can reach 1.90 times that under the far-field earthquakes.The characteristic fitting period and PGV/PGA greatly influence the structure's seismic performance index.Before and after strengthening,the correlation coefficient between the drifts and the characteristic fitting period is 0.90 and 0.82,respectively.The research may provide reference for seismic performance evaluation and strengthening design of existing RC frame school buildings.