Application And Research Of Adaptive Element In Foundation-structure Dynamic Interaction

In this paper,the dynamic analysis of the structure-infinite foundation is carried out by the coupling method of time-domain boundary element and finite element.In the solution process,the time-domain boundary element method combined with adaptive elements is used to simulate the infinite foundation,and the finite element method is used to model the superstructure,foundation and near-field foundation.The two methods are coupled through the coordinated relationship between force and displacement at the common interface of the two subdomains,and then the dynamic interaction between the foundation and structure is studied.There are mainly the following aspects of research in this article:(1)Transforming the far-field semi-infinite boundary into an adaptive semi-infinite boundary element that can simulate the radiation damping effect in the far area based on the theory of time-domain boundary element method and the propagation characteristics of stress wave in elastic medium,and the element was combined with the conventional time-domain boundary element method to solve elastic half-plane dynamic problems.The adaptive semi-infinite boundary element is actually a finite element that can automatically adjust its size according to time-space parameters.Therefore,it is possible to perform numerical calculations such as singularity processing on the influence coefficient of the element by conventional time-domain boundary element method.Finally,an elastic half-plane example under dynamic load is used for verification.The verification shows that the adaptive semi-infinite boundary element can effectively simulate the far-field radiation damping and the time-domain boundary element method using this element can efficiently solve elastic half-plane dynamic problems.(2)Research on the coupling algorithm of time-domain boundary element and finite element.When using the coupling method for analysis,the solution domain is divided into a finite domain subdomain and a time domain boundary element subdomain.The Newmark precise integration method is used for finite element dynamic analysis,and the coordinated relationship between the force and displacement at the common boundary of the two subdomains is used to continuously iterate the displacement and force of the nodes on the common boundary,thereby completing the iterative coupling of the two methods.(3)Based on the above research,the finite element method is used to simulate the superstructure,foundation and near-field foundation,the time-domain boundary element method is used to simulate the far-field infinite foundation.The calculation example of the foundation-structure dynamic interaction was analyzed by the coupling method.The verification shows that 1)Compared with the conventional fixed boundary method,the coupling method in this paper can reduce the peak of the structural displacement response by about 20%to 30%,and as the foundation flexibility increases,the decrease in the peak of the displacement of each floor is greater.It also shows that the softer the foundation soil is,the more it is affected by radiation damping.2)The structural response after considering the dynamic interaction is greater than that assumed by the rigid foundation,and the softer the foundation,the greater the displacement response of the structure.Therefore,it is important to consider the influence of foundations(especially soft foundations)in structural design.