土体-框架结构振动台模型实验研究

Experimental Study on Shaking Table Test of Soil-frame Structure

在进行土体-框架结构的振动台模型实验中,测出了模型体系的加速度、位移和应变反应.首先分析了实验各阶段系统的自振频率及阻尼比的变化情况,然后着重比较了各工况下框架结构的加速度、层间位移和应变反应规律,并与刚性地基实验进行了对比.实验结果表明,相对于仅有水平激振,竖向激振的参与可使结构的反应增加,且位移、应变反应的增量要大于加速度反应的增量;桩体应变要小于框架上的应变;基础上的加速度反应要大于土表反应.土-结构相互作用下的测试结果普遍要大于刚性地基情况下的结果,并且加速度峰值、层间位移峰值沿楼层的变化趋势也不相同,基于刚性地基假定下的计算结果可能偏于不安全,对于结构的抗震设计考虑土-结构相互作用的影响很有必要.

During the shaking table test of soil-frame structure interaction, the acceleration responses, tlae displacement responses and the strain responses of model structure were measured. In this paper, the change in natural frequencies and relative damping ratios of model were first analyzed, and then the rules of the earthquake responses which include acceleration, displacement and strain were compared under different conditions. Also the results were compared with rigid foundation test. The test results show that, the reaction of structure is greater under two-dimensional excitation than under one-dimensional excitation, and the incremental of displacement and strain response are larger than the acceleration response. The strain on the pile is less than the strain on the frame. The acceleration response of the base is larger than that of the soil surface. The test results under soil-structure interaction are generally larger than the results of the rigid foundation. The peak value of acceleration and interlayer displacement are different along the floor. The calculation results based on the assumption of rigid foundation may be unsafe. It is necessary to consider the influence of soil structure interaction on the seismic design of structure.