Meshless Computation Method Of Raft Foundation And Its Application To Interaction Analysis With Superstructure

Meshless method is a new numerical computation method that is developed rapidly in recent years. Without element mesh and based on the dispersed nodes to form approximate interpolative function dynamically, meshless method has distinct difference with traditional finite element method. Meshless method conquers the problems caused by mesh generation, mesh aberration and mesh move. With provides a new effective means to engineering problem, meshless method obtain highly recognition in international compute mechanics domain and engineering field.Based on the developing trends of the meshless numerical analytical method and the interaction research of raft foundation with soil and superstructure, meshless computation methods for elastic foundation plate are researched by using the relative works in existence for reference adequately. And this elastic foundation plate meshless method computation theory is used in the interaction numerical analysis of raft foundation with soil and superstructure.The main work and innovative achievements are as follows:①The 1st and 2nd derivatives to the shape functions of reproducing kernel particle method (RKPM) and natural element method (NEM) are deduced in two-dimensional domain. With the application of above derivatives to plate bending C1 problem (Which require shape function has continuous derivative in its definition domain), meshless method analysis theory is built for Kirchhoff thin plate bending on Winkler foundation and thus promote the development of elastic foundation thin plate theory. Among these work, 2nd derivative to the shape functions of NEM and the RKPM, NEM meshless method of Kirchhoff thin plate bending on Winkler foundation are innovative.②Based on the meshless method analysis theory of Kirchhoff thin plate bending on Winkler foundation, meshless method analysis theory of Kirchhoff thin plate bending on two-parameter foundation is developed. This broaden the foundation application area of elastic foundation thin plate bending analysis meshless method and make the theory accord with the practice much more. Among these work, RKPM, NEM meshless method of Kirchhoff thin plate bending on two-parameter soil foundation are innovative.③Meshless method analysis theory of Mindlin medium-thick plate bending on Winkler and two-parameter foundation is built. Element-free Galerkin method (EFGM), reproducing kernel particle method (RKPM), natural element method (NEM) are used to solve Mindlin medium-thick plate bending problem with the above theory and thus promote the development of elastic foundation medium-thick plate theory. The theory can also be used in the computation of thin, medium-thick and thick plate in elastic foundation. Based on the agility property of node disposal in meshless method, the theory can be used in the bending problem of foundation plate with arbitrary plane shape. Among these work, RKPM, NEM meshless method of Mindlin thick plate bending on Winkler foundation and RKPM, EFGM, NEM meshless method of Mindlin thick plate bending on two-parameter foundation are innovative.④By coupled the sub-structure finite element method for frame-superstructure and the meshless method (Which include EFGM, RKPM, NEM) for raft foundation, a new method is built for the interaction analysis of high-rise frame superstructure with raft foundation and soil. With the example computation analysis and comparison with ANSYS finite element soft computation result, the method is proved to be effective and feasible.⑤By couple the finite element sub-structure method for superstructure that used shear-wall and floor-slab element and the meshless method for foundation plate, a new analysis method for interaction analysis of high-rise frame and shear-wall superstructure with raft foundation and soil is built. The method can be used to analysis the interaction of different superstructure (Such as frame and shear-wall structure, tube structure, frame and tube structure etc.) with raft foundation and soil. With the example computation analysis and comparison with ANSYS finite element soft computation result, the method is proved to be effective and feasible.⑥Pointed to the various computation theory and analysis content, computation program PIASRFS-2007 is devised with C++ language in VC++ platform. Raft foundation can be analyzed by this program. And interaction of raft foundation in different plane shape and different thickness with soil that simulated by Winker or two-parameter soil model and high-rise building superstructure can be computed and analyzed. The program provides a new and effective analysis tool for the practice of high-rise building raft foundation engineering. By the computation of program, data which concerned in engineering such as deflection of raft foundation (soil settlement), internal force of raft foundation, internal force of superstructure (Which include beam, columns and shear-wall) and the other useful data for structure design can be obtained. And this can provide guidance and advice for the relative engineering practice.