考虑支座失效的基础隔震结构振动台试验研究

Shaking Table Test Study of a Base-isolated Structure Considering an Isolation Bearing Failure

为研究隔震结构在多向动力耦合激励下的动力响应和荷载传递路径,进行了一个缩尺比例为1∶4的三层平面不规则RC隔震框架结构振动台试验.通过研究结构的加速度响应、位移响应、隔震支座内力响应、损伤跨梁混凝土和钢筋应变等,揭示了多向动力耦合激励下的抗倒塌性能.进一步利用OpenSees有限元软件,分析了损伤跨梁内力和支座损伤指数分布规律.研究结果表明:在双向水平地震和单个隔震支座突然失效引起的竖向不平衡荷载耦合激励下,失效点位置处结构的竖向动力响应显著增大,并发生明显的竖向变形;支座瞬时失效产生的动力效应对各支座内力均有影响,特别是对相邻支座的内力影响更加明显;支座瞬时失效产生的竖向不平衡荷载由空腹效应和梁端弯矩共同抵抗;支座瞬时失效对相邻支座损伤指数影响最大;在多向动力耦合激励下失效区域的动力响应比仅考虑竖向不平衡荷载下更显著,隔震层损伤指数分布相比地震单独作用下更加离散.

To investigate the dynamic response and load transfer path of the isolated structure subjected to multi-direction coupled dynamic excitation,a 1∶4 scale model shaking table test of a three-story irregular plane RC frame isolated structure was conducted.The progressive collapse resistance under multi-direction coupled dynamic excitation was revealed by studying the acceleration response,displacement response,internal force response of the isolation bearing,and concrete and reinforcement strains of the damaged span beam of the structure.Then,the distribution laws of the internal force of the damaged span beam and the damage index of the isolated bearing were analyzed by OpenSees.The results show that under the coupled excitation of the vertical unbalanced load caused by sudden failure of a single isolated bearing and bidirectional horizontal earthquake,the vertical dynamic response at the failure point increases significantly,and the markedvertical deformation occurs.The dynamic effect caused by isolated bearing transient failure has an influence on the internal force of all remaining bearings.In particular,the impact on the neighboring bearing’s internal force is more visible.Vierendeel action and beam end bending moment resist the vertical unbalanced load generated by isolated bearing transient failure.The damage index of neighboring bearings is most affected by the isolated bearing transient failure.The dynamic response of the failure zone under the multi-directional dynamic coupling excitation is more pronounced than that under the vertical unbalanced load only,and the damage index distribution of the isolation layer is more discrete than that under earthquakes only.