土-桩-偏心结构相互作用体系振动台试验研究

Shaking table test of soil-pile-eccentric structure interaction system

为研究土与结构动力相互作用对偏心结构地震反应的影响规律,改进现有抗震设计,采用振动台试验方法对某单层偏心结构模型在刚性地基与桩筏基础条件下进行对比试验,对模型制作材料力学性能进行了测试,分析和比较了偏心结构位移响应组成关系。结果表明:地基刚度对结构自振特性的影响主要表现为振型间耦联反应程度的降低和体系阻尼比的增大;地基对基础的约束能力影响了上部结构振动反应的大小与组成,考虑相互作用的偏心结构平扭变形幅度降低,总位移反应增大;结构应变反应振动频率降低,振动持时缩短,场地土的阻尼特性加快了结构振动能量的耗散;当偏心率较小时,结构主要表现为单自由度体系变形特征,扭转耦联效应随之减弱。试验结果为后续理论研究提供了依据。

In order to study the effect of soil-structure interaction on the earthquake response of eccentric structure and improve current seismic design code, a shaking table test of soil-pile-eccentric structure interaction system was carried out and compared with fixed base foundation test. The mechanical properties of materials used in the test were measured. The composition of displacement response of eccentric structure was analyzed and compared. Test results suggested that the lateral-torsional coupling degree decreased and the damping ratio increased due to foundation flexibility. The constraint of foundation influenced the amplitude and component of superstructure vibration response. The elastic deformation reduced when SSI effect was taken into account, while the total displacement increased. The vibration frequency and the duration of strain response were slower and shorter than those of fixed base tests. The damping feature of foundation soil speeded up the dissipation of structure vibration energy. As eccentricity ratio decreases, the superstructure performed like a single DOF system and the lateral-torsional coupling degree significantly reduced. The test results provide experimental background for further theoretical research.