The Algorithm Research To Ultimate Load Of Statically Indeterminate Non-uniform Member Structure

With the maximization of engineering machinery,its mechanical property has become an important research field.The key point of large variable cross-section of the steel structure is the analysis of ultimate load and critical load.The calculation is bound up with structural parameter.It cannot be calculated directly by structural mechanics and materials mechanics.At present,the common methods have some problems like tedious calculation and complex counting in calculating this kind of variable cross-section construction.Therefore,it has theoretical and practical value to propose an effective algorithm.Firstly,this thesis proposed an optimization algorithm to calculate the ultimate load of variable cross-section statically indeterminate beam based on the elastoplasticity analysis.Taking ultimate load,extra constraining force and deflection corresponding coordinates as design variables,and taking bending moment of different coordinates and satisfaction conditions of shearing force as objective function.The calculating and result of ultimate load was implemented by means of Mathematica and Ansys software.Secondly,regarding statically indeterminate variable cross-section compression bar as research object,the nonlinear differential equation in a state of equilibrium was discretized with difference theory.Taking the deflection of every discrete point,critical load and extra constraining force as design variable,the objective function meet difference theory and boundary conditions to propose an unconstrained optimization algorithm for ultimate load.The Fortran-PowerStation was used to program procedure to solve specific example.Finally,this thesis proposed a critical load optimization algorithm to analyze the statically indeterminate variable cross-section rigid frame with different constraints.Practical calculating examples were analyzed and program was made out.The calculating-examples analysis demonstrated the effectiveness of the optimization algorithm.This thesis proposed a feasible calculating method to solve the problem of variable cross-section stability ultimate load for mechanical engineering and constructional engineering.