跨地裂缝框架结构地震响应振动台试验研究

Shaking table test on seismic response of frame structures across the ground fissure

为研究地裂缝环境下结构的动力响应规律,首次进行跨地裂缝结构和无地裂缝环境下结构振动台对比试验,分析地震作用下跨地裂缝结构的破坏形态、动力特性、加速度响应、位移响应和应变响应。研究结果表明:地震波传至上盘和下盘地表的峰值加速度、峰值时间、频率及相位等均存在差异,形成非一致性地震激励;此外,地裂缝场地对土层加速度有放大效应,同一层土的最大加速度出现在靠近地裂缝的上盘处。跨地裂缝结构处于上盘的构件损伤程度明显大于下盘;在相同地震激励作用下,跨地裂缝结构的动力反应与无地裂缝环境工况相比更加剧烈。跨地裂缝结构的侧向位移最大值并不是全部出现在顶层,这是由于地裂缝上下盘的不均匀沉降作用和基础附加变形综合造成的。跨地裂缝结构的柱钢筋应变幅值分布具有上下盘分布规律,即处于上盘柱的钢筋应变幅值明显大于下盘柱。研究成果可为地裂缝环境下结构设计提供参考。

To study the dynamic response of structure in ground fissure environment,shaking table tests were firstly conducted for the comparison of structure across the ground fissure and structure on the unfissured ground.Some analyses were performed on the structure across the ground fissure under earthquake for its failure pattern,dynamic properties,acceleration responses,displacement responses and strain responses.The results are as follows:intensity,peak time,frequency and phase of the seismic waves reaching the ground surfaces of hanging wall and footwall were different,forming the non-uniform seismic excitations.Moreover,the site with ground fissure had an amplification effect on acceleration of soil layer,and the maximum acceleration of the same soil layer occurred at the hanging wall near the ground fissure.For the structure across the ground fissure,structural components on the hanging wall suffered more damage than those on the footwall.Under the same seismic wave input,the seismic response of the structure across the ground fissure was more significant than that in the site without ground fissures.In addition,the maximum lateral displacement of the structure across the ground fissure may not appear at the top floor,which is due to the combination of the uneven settlement caused by the ground fissure and the additional deformation of the foundation.The strain amplitude distribution of the column reinforcement in the structure across the ground fissure showed the hanging wall/footwall effect,that is,the strain amplitude of the column reinforcement on the hanging wall shall be significantly greater than that on the footwall.The research results can provide reference for structural design under the ground fissure environment.