黏滞阻尼器参数对RC框架减震加固结构的易损性影响分析OA

Against the backdrop of urban renewal,adopting seismic energy dissipation retrofit technologies to enhance the safety reserves of building structures under strong earthquakes has become one of the research hotspots in civil engineering.However,studies on the influence of the damping coefficient on the seismic performance of medical buildings retrofitted with viscous fluid dampers(VFD)remain insufficient.To investigate the effect of damping coefficients on the seismic retrofitting performance of medical buildings,a five-story reinforced concrete(RC)frame outpatient building designed to maintain normal functionality during the design basis earthquake(DBE)is taken as a case study.Four seismic retrofitting schemes with different damping coefficients are designed.Based on an elastoplastic model established in ETABS,nonlinear dynamic time history analyses under DBE and maximum considered earthquake(MCE)levels are conducted.Furthermore,incremental dynamic analyses(IDA)using 20 ground motions are conducted to establish a fragility matrix with the maximum inter-story drift ratio as the engineering demand parameter,and the collapse probability and collapse safety margin are subsequently evaluated.The results indicate that:With increasing damping coefficient,the inter-story drift ratio,damage exceedance probability,and collapse probability generally decrease,and the structural safety reserve is improved;Under DBE,the floor acceleration exhibits a non-monotonic trend of first decreasing and then increasing with increasing damping coefficient,and the top-floor acceleration at the roof reaches a minimum value of 228 gal when C=1 500 kN/(s/m)α;under MCE and higher-intensity ground motions,the acceleration generally decreases,and when PGA≥0.7 g,the location of the peak floor acceleration(PFA)shifts from the top story to lower stories;Compared with the scheme of C=500 kN/(s/m)α,for C=1 500 kN/(s/m)α,the maximum inter-story drift ratio under DBE decreases from 1/457 to 1/571,the collapse probability under extreme earthquakes decreases from 5.54%to 3.16%,and the collapse safety margin increases from 2.82 to 3.06;Considering the inter-story drift ratio,floor acceleration,and damage-risk indices comprehensively,C=1 500 kN/(s/m)α is recommended for this case study.The results can provide a reference for parameter selection and performance-based evaluation of VFDs in similar medical buildings.