A retrofit procedure for existing buildings called the ＂weakening and damping technique＂ （WED） is presented in this paper. Weakening of structures can limit the maximum response accelerations during severe ground ...A retrofit procedure for existing buildings called the ＂weakening and damping technique＂ （WED） is presented in this paper. Weakening of structures can limit the maximum response accelerations during severe ground motions, but leads to an increase in the displacements or inter-story drifts. Added damping by using viscous dampers, on the other hand, reduces the inter-story drifts and has no significant effect on total accelerations, when structures behave inelastically. The weakening and damping technique addresses the two main causes for both structural and nonstructural damage in structures. The weakening retrofit is particularly suitable for structures that have overstressed components and weak brittle components. In this paper, the advantages of the WeD are verified by nonlinear dynamic analysis and simplified spectral approach that has been modified to fit structures with additional damping devices. A hospital structure located in the San Fernando Valley in California is selected as a case study. The results from both analyses show that the retrofit solution is feasible to reduce both structural acceleration and displacement. A sensitivity analysis is also carried out to evaluate the effectiveness of the retrofitting method using different combinations of performance thresholds in accelerations and displacements through fragility analysis.展开更多
The seismic behavior of a structural system composed of pre-stressed concrete stand supporting a retractable steel roof was studied,which is typically based on the prototype of engineering project of Shanghai Qizhong ...The seismic behavior of a structural system composed of pre-stressed concrete stand supporting a retractable steel roof was studied,which is typically based on the prototype of engineering project of Shanghai Qizhong Tennis Center.By elasto-plastic finite element analysis and shaking table test,the following were investigated:the effects of roof configurations in opening and closing,the effect of pre-stress on the structural seismic response,and the failure mechanism of the spatial stand frame systems featured with circularly arranged columns and inverse-cone type stands.It was found thatthe roof status has great effect on the natural period,vibration modes,and seismic response of the whole structure,the stand response to horizontal seismic excitation is stronger in roof opening configuration than in closing state,and the response mode is dominantly translational rather than rotational,though the stand is characterized by its fundamentally torsional vibration mode.The study indicated that the pre-stressed inversecone stands can keep the system from global side-sway collapse under gravity loads,even in the case that most columns loose moment capacity.展开更多
基金MCEER, Through a Grant from the Earthquake Engineering Research Centers Program of the National Science Foundation Under Grant No. EEC-9701471
文摘A retrofit procedure for existing buildings called the ＂weakening and damping technique＂ （WED） is presented in this paper. Weakening of structures can limit the maximum response accelerations during severe ground motions, but leads to an increase in the displacements or inter-story drifts. Added damping by using viscous dampers, on the other hand, reduces the inter-story drifts and has no significant effect on total accelerations, when structures behave inelastically. The weakening and damping technique addresses the two main causes for both structural and nonstructural damage in structures. The weakening retrofit is particularly suitable for structures that have overstressed components and weak brittle components. In this paper, the advantages of the WeD are verified by nonlinear dynamic analysis and simplified spectral approach that has been modified to fit structures with additional damping devices. A hospital structure located in the San Fernando Valley in California is selected as a case study. The results from both analyses show that the retrofit solution is feasible to reduce both structural acceleration and displacement. A sensitivity analysis is also carried out to evaluate the effectiveness of the retrofitting method using different combinations of performance thresholds in accelerations and displacements through fragility analysis.
文摘The seismic behavior of a structural system composed of pre-stressed concrete stand supporting a retractable steel roof was studied,which is typically based on the prototype of engineering project of Shanghai Qizhong Tennis Center.By elasto-plastic finite element analysis and shaking table test,the following were investigated:the effects of roof configurations in opening and closing,the effect of pre-stress on the structural seismic response,and the failure mechanism of the spatial stand frame systems featured with circularly arranged columns and inverse-cone type stands.It was found thatthe roof status has great effect on the natural period,vibration modes,and seismic response of the whole structure,the stand response to horizontal seismic excitation is stronger in roof opening configuration than in closing state,and the response mode is dominantly translational rather than rotational,though the stand is characterized by its fundamentally torsional vibration mode.The study indicated that the pre-stressed inversecone stands can keep the system from global side-sway collapse under gravity loads,even in the case that most columns loose moment capacity.
