不同土性的地基-结构动力相互作用振动台模型试验对比研究

通过结构-地基动力相互作用(SSI)体系的振动台模型对比试验,研究了不同土性的地基条件对动力相互作用效果和规律的影响。在试验现象方面发现,地基土越软弱,结构沉降和倾斜越大;不同土性条件下结构裂缝形态相似,但土越硬,裂缝出现越早,发展也越严重。在体系动力特性方面发现,SSI体系频率均小于不考虑SSI的结构自振频率,阻尼比大于结构材料阻尼比,但不同土性条件时由于土、基础、结构三者刚度比不同,SSI对动力特性的影响程度和机理存在差异。在地震反应方面发现,土越硬,加速度反应的峰值放大系数越大;加速度反应的主要组成成分和频谱特征是,土较软时以基础转动引起的摆动分量和平动分量为主;土较硬时以结构弹塑性变形分量为主。结果表明在不同地基土性条件下,结构-地基动力相互作用具有相似的规律,但其效果和机理存在差异。

Comparative study on the dynamic soil-structure interaction system with various soils by using shaking table model tests

Through comparing the shaking table tests on dynamic Soil-Structure Interaction(SSI) systems,the effects of various soils on SSI are studied.Test results indicate that the softer the soil is,the larger the subsidence and inclination of the superstructure become.The crack patterns in the superstructure are similar under various soil conditions,but the cracks appear earlier and develop more severely if the soil is hard.The natural frequency of the SSI system is less than that of the structure when SSI is not taken into account and its damping ratio is larger than that of structural material.But the mechanism and degree of these effects is quite different,because the relative stiffness ratios between soil,foundation and superstructure are different under various soil conditions.The seismic response indicates that the harder the soil is,the larger the magnification coefficient of the acceleration response is.The acceleration response of soft soil is mostly composed of rocking and swing whereas hard soil exhibits elastic and plastic deformations.The results indicate that there exist similar behaviors of SSI under various soil conditions,although the mechanism and degree of these behaviors are different.