The Stochastic Seismic Response Analysis And Dynamic Reliability Study On Pile-Soil-Structure Interaction System

Pile foundation is widely used in many countries all over the world. The serious damage in pile foundations, however, is observed during the past strong earthquakes. Owing to the invisibility of pile foundations, the repair work of their damage is very complicated and large amount of cost must be paid.Pile-soil-structure dynamic interaction exists universally. The earthquake motion, however, is apparently random in time, space and amplitude." So it is necessary to perform the stochastic vibration analysis and reliability research on pile-soil-structure dynamic interaction system.At present, the research achievements on the stochastic seismic response analysis of pile-soil-structure interaction system are very few. Besides, the research on combined stochastic response of pile-soil-structure interaction system with structural parametric variability is very difficult and seldom read in the printed papers, which is a front subject in the earthquake engineering. The research on that field is very significant and meaningful, which will be helpful to the structural anti-seismic design and dynamic reliability of pile foundations.Based on structural seismic theory, stochastic vibration theory and structural dynamic reliability theory, the dynamic response of pile-soil-structure interaction system is studied in this dissertation, in which the methods of stochastic seismic response and dynamic reliability for pile-soil-structure interaction system are discussed, the statistical characteristics of seismic response of pile-soil-structure interaction system is analyzed and the seismic reliability of pile-soil-structure interaction system is investigated. This dissertation focuses on some problems as follows:Firstly, considering the randomness of earthquake and the nonlinearity of soil, introducing viscous-spring boundary and the orthogonal trial method, the loading mode of inputting acceleration directly in harmonic response analysis is proposed and the parametric sensitivity analyses of stochastic vibration response for pile-soil-superstructure interaction system based on pseudo-excitation method, equivalent linearization method and definite dynamic finite element method are proposed.The parametric sensitivity analyses of pile-soil system with respect to pile-soil modulus ratio, earthquake design level, and pile slenderness ratio are conducted. In succession, comprehensive parametric analyses have been conducted for a shear-type structure supported by a single pile. The results show that the method introducing the orthogonal trial method into the parametric sensitive analysis of the stochastic seismic response analysis of pile-soil- structure interaction system is relatively effective.Secondly, the stochastic seismic responses of pile-soil-structure interaction system for different sites and different earthquake levels are analyzed comprehensively. The effects of pile-soil-structure interaction and soil nonlinearity on the stochastic response are compared.Thirdly, considering the pile-soil-structure dynamic interaction, the randomness of earthquake, the nonlinearity and variation of soil, the combined stochastic vibration analysis method for pile-soil-superstructure interaction system is proposed based on the small parametric perturbation method, pseudo-excitation method, equivalent linearization method and definite dynamic finite element method, effects of the variation of shear modulus, damping ratio, density and Poisson's ratio on the stochastic seismic response of the pile-soil-structure interaction system at the nonlinear stage is studied chiefly.Fourthly, based on the rules of maximum theory and first excursion failure theory Adopting anti-seismic calculation method of taking the same reliability value of pile and structure, the dynamic reliability of pile-soil-structure interaction system are studied using the dual design guideline of strength and deformation in the conditions of considering the randomness of material parameters and not considering the randomness of material parameters.