近场脉冲型强震下基础隔震结构的非线性反应与限位分析*
- 摘 要
-
（1 福建工程学院土木工程学院， 福州 350118； 2 湖南大学土木工程学院， 长沙 410082）
［摘要］近场地震动是具有长周期、短持时、高能量的速度脉冲运动，其对基础隔震的减震性能产生不利影响。建立一幢10层钢筋混凝土框架基础隔震的有限元模型，分析其在近场脉冲型强震与常规强震作用下的非线性反应，探讨速度脉冲对层间弹塑性位移、层间剪力、隔震层变形及隔震结构塑性铰分布的影响。提出在隔震层增设黏滞阻尼器，形成混合隔震方案，分析其对隔震层的限位保护效果及其对隔震结构非线性反应的减震效果。结果表明：基础隔震在速度脉冲近场强震作用下的非线性反应较常规强震显著增大；隔震层最大变形显著增加，远超过了隔震支座容许变形值。考虑近场影响系数不能有效反映长周期速度脉冲对隔震结构的不利影响。混合隔震能有效控制隔震层上部结构的非线性反应与隔震层最大变形，避免隔震支座破坏而导致上部结构倾覆失稳。［关键词］基础隔震; 近场地震; 混合隔震; 非线性反应; 隔震层限位中图分类号：TU352.1 文献标识码：A 文章编号：1002-848X(2016)11-0096-06
Nonlinear responses of base-isolated structures and limiting deformation of isolation layers under near-field pulse-like strong ground motionsYan Guiyun1,2, Xiang Hong1, Zhang Zheng1, Chen Shengfu1, He Mengchao1(1 College of Civil Engineering, Fujian University of Technology, Fuzhou 350118, China;2 College of Civil Engineering, Hunan University, Changsha 410082, China)Abstract: Near-field ground motions are characterized by horizontal pulse motions of velocity with long period, short duration and high energy, which exert adverse impacts on base-isolated structures. The finite element model of a base-isolated building with 10-story reinforced concrete frame structure was set up to analyze seismic responses of the building when subjected to near-field pulse-like and common strong ground motions. The effects of velocity pulse on interstory plastic drifts, interstory shear forces, deformation of isolation layer as well as distribution of plastic hinges were explored. Then, the hybrid isolation which had viscous dampers installed on the isolation story was developed, and its influences on limiting deformation of isolation layer and reducing nonlinear response were discussed. The results show that nonlinear responses of the base-isolated structure subjected to ground motions with velocity pulse are much greater than those subjected to common ground motions. The maximum deformation of isolation layer obviously increases and is far beyond the allowable deformation of isolation bearings. The negative impacts of long-period velocity on the base-isolated structure cannot be taken into account through near-field influence coefficient. The results also indicate that the hybrid isolation can significantly decrease nonlinear responses of the superstructure above the isolation layer and the maximum deformation of isolation layer, preventing collapse of the superstructure caused by isolation bearings destruction.Keywords: base isolation; near-field pulse-like ground motion; hybrid isolation; nonlinear response; limiting deformation of isolation layer
*国家自然科学基金资助项目(51378124)，福建省教育厅项目(JA15324;JA11185)。作者简介：颜桂云，博士，副教授，Email：yanguiyun@sina.com。
