Non-stationary Random Seismic Analysis Of Submarine Pipelines Subjected To Spatially Varying Ground Motions

In recent years,with the excessive consumption of land resources,the exploitations of marine resources have been increased rapidly.As a result,a large number of oil and gas pipelines have been laid on the deep seabed.Due to the randomness and complexity of the marine environment,the dynamic response analysis of submarine pipelines subjected to ground motions has been a fundamental problem of interest.Based on the pseudo-excitation method and Leung's method,this paper presents a novel method for non-stationary random seismic response analysis of submarine pipelines subjected to spatially varying ground motions.The non-stationary random seismic responses are proven to be represented in terms of deterministic transient dynamic responses subjected to multi-support pseudo ground acceleration excitations.Since the transient response of structure is directly derived from its steady state response and the initial condition,the present method has significant advantages in computational efficiency and the derivation process is quite simple.The paper is structured as follows:1)Leung's method and Lee's method are used to analyze transient responses of the spring-mass system and the three plant system.The basic ideas of Leung's method and Lee's method are explained in detail,and both the advantages and disadvantages of these two methods are compared.2)It is proven that the non-stationary random seismic responses can be represented in terms of deterministic transient dynamic responses subjected to multi-support pseudo ground acceleration excitations.Then,discrete governing equations in the forms of finite element method are established.Finally,based on the pseudo-excitation method,the pseudo dynamic relative displacement of all non-support nodes are solved by the Newmark method,Leung's method and Lee's method.And the computational efficiencies of these three methods are compared.3)Considering the dynamic behavior of pipelines and water under the earthquake,discrete governing equations in the forms of finite element method are established.Subsequently,the pseudo dynamic relative displacements are derived from the Newmark method and Leung's method based on the pseudo-excitation method.Finally,the deterministic transient dynamic responses of all non-support nodes under multi-support pseudo ground acceleration excitations are derived.Meanwhile,the non-stationary random seismic responses of submarine pipelines subjected to spatially varying ground motions are analyzed.