考虑反演及桩土相互作用的拟动力试验方法

考虑桩-土-结构相互作用,建立整个结构体系试验模型,在土槽试验室模拟框架结构在地震作用下的反应.在考虑桩-土相互作用的拟动力试验中,由于下部结构的不可控性和土体的不确定性,提出采用反演分析识别下部结构的动力反应,试验中通过传感器有效获取下部结构状态信息,利用这些测试信息作为反演分析的基础数据,确定桩-土工作状态,运用子结构的概念完成整个结构体系的拟动力试验.以某框架为例,采用考虑反演分析的试验方法、等效线性化方法以及刚性地基假设方法,探讨地震作用下结构反应的不同.试验及模拟分析表明,地震作用下,土体较早地进入了塑性阶段,结合反演分析的该试验方法能更好地模拟包括桩土在内的整个体系在地震下的反应.考虑反演分析试验方法的结构顶端位移最大,等效线性化方法次之,刚性地基假设最小;考虑反演分析试验方法的层间位移角和层间剪力最小,固定基础假设最大.

Inverse Analysis Method for Pseudo-dynamic Test with Pile-soil Interaction

A new method was proposed for the assessment of frame structure under seismic excitation in the lab with the consideration of pile-soil interaction. In this method, an inverse model was proposed to identify the dynamic response from the substructure, the model, which relates sensor's data to the working state of the piles in the test system, was used to reduce the errors caused by uncontrollable of substructure and uncertainty of soil.Test validation was conducted by an idealized frame structure separately in this model, equivalent linearization method and the rigid foundation assumption. Numerical simulation and the tests data show that, under seismic excitations, the soil would experience plastic stage at the beginning of the excitations, and the new proposed method had a great advantage in the simulation of the pile-soil interaction. For the top displacement in the test structure, maximum displacement was found in the inverse model, followed by the equivalent linearization method, minimum in the rigid foundation assumption; however, for the drift ratio and inter-story shear, the former order was inversed.