The QR Method Of Plane Steel Frame Elastic Plastic Analysis And Program Design

Taking the influence of material nonlinearity and geometric nonlinearity of plane steel frames into consideration,based on the layer fiber model and three-stage linear distribute rigidity model,using VC6.0 program software,the QR method of the elastic-plastic analysis of the plane steel frame was written.The program not only describes the plastic development along the section height of gradient process of plane steel frame structure,but also describes the gradient process of bar length.This program abandon the approach of current specification of steel structure which determines the most adverse internal force basing on the linear superimposition theory and dependents on the calculated length coefficient to evaluate approximately the relevance of structural overall stability and local stability and avoid complicated calculation process of single component and significantly improve the computational efficiencyThe main research methods are as follows:Approach one:based on the flat section assumption and layer fiber model,taking section transient extensional rigidity EA and section transient flexural rigidity EI of beam-column element with plastic gradient along the section height into consideration,the C language program—Solve_EA_EI.c is written to solve the transient rigidity value of the beam-column elements under the elastic plastic state.Approach two:the basic principle of the QR method is introduced in this paper which is used to analysis the plane steel frame.Approach three:using three-stage linear distribute rigidity model,the distribution of the plastic zone model was deduced under the element stiffness matrix,including the first order and second order elastic-plastic analysis of element stiffness matrix.The QR method of nonlinear analysis of plane steel frame format is compiled and has compared the result with the related literature of typical cases and analysis of finite element simulation results,the efficiency,practicability and accuracy of this method was verified.The research shows that:compared with the plastic hinge model,using three-stage linear distribution of plastic zone model for steel frame structure of lateral have increased effect,this paper adopted by the model can not only determine the plastic deformation along the section height of gradient process,and can also determine the plastic deformation along the rod long gradient process,overcoming the concentrated plasticity model to plastic limit in finite element nodes,and according to the height and length of the gradient,the gradient of plastic zone can be comprehensive assess the extent of plastic zone.Using QR calculation program compiled text not only improve the calculation efficiency and accuracy,but also according to the development direction of the plastic,the preliminary estimate of the structure of the weak layer,provides new way for optimal design of structure.Considering the second order effect at the same time,amount of lateral steel frame at the top will increase further,ductility improved and ultimate bearing capacity reduced.In addition,the plastic expansion order is slightly different from that of the plastic hinge model.The accuracy of result in this paper is relatively high.