Application Of Fire Resistance Limit Of Steel Frame Joint Under Fire Condition By The Improved Element-free Galerkin Method

As the most popular numerical calculation method,finite element method has been widely used in various engineering fields.However,due to the limitation of the grid,it is very inconvenient to deal with the problems of time discontinuity and large deformation.In order to solve this problem,meshless method came into being as a computing method without grid division.In recent years,this method has become a research hotspot because it can effectively deal with the problems that cannot be solved by traditional finite element method.As the most mature meshless method,many scholars have done a lot of research on the properties and improvement of the element-free Galerkin method.In this paper,the moving least square method is improved by orthogonal basis function and singular weight function.Because this method avoids the ill-condition of matrix inverse and makes the type function have interpolation characteristics,it provides convenience for the application of EFGM.Then the factors affecting the calculation accuracy are discussed such as base function,weight function,support domain radius,node distribution,etc.The improved EFGM is woven into a program for solving the transient heat conduction problem and the elastic-plastic problem.Through the example analysis,the applicability and superiority are verified.With the increasing proportion of steel structure engineering in building engineering in China,many scholars began to study how to improve the fire resistance of steel structure through design.This paper analyzes the stress-strain relation in solving the fire resistance limit problem and then writes the corresponding program through the method of sequential coupling.The applicability and accuracy of the improved EFGM were verified by the simulation results of the steel frame joints in the case of fire.Finally,the fire resistance of the joints under different loads and different structural sizes is studied.The results show that the reduction of beam end load and the increase of beam section height,web thickness and flange thickness have positive effects on the improvement of fire resistance of joints.