Fatigue Considered Research On Optimal Model Of Corrugated Web Girders

Corrugated web girder is a new kind of girder structure,which has been widely used in the field of mechanical and architecture.However there are only few studies focused on the optimal design of corrugated web girders,and often the fatigue performances are not considered.Aiming at the fatigue performances,much research was done in this paper,and finally the optimal model was constructed.The main study of this paper can be concluded as below:1)Geometric constraint relationship among the structural parameters of corrugated web girder was studied and analyzed,and 3 ratio-type variables were introduced to eliminate correlation among design variables,and a group of 36 representative samples were selected for the establishment of further surrogate model by means of latin hypercube design;2)The 4 points bending finite models of sampling girders were built by using an unified standard,the number of typical wave structural at constant bending section area is 5,and the average value of equivalent structural stresses at S point among the middle3 wave sections,was calculated as the characterization stress.The effects of spans and loads were eliminated by introducing the concentration factor of equivalent structural stress,and the relationship between equivalent structural stress and the structural parameters of corrugated web girder was then reflected directly;3)On the basis of FEM results,the surrogate model for the equivalent structural stress concentration factors of corrugated web girders was constructed with the method of SVM,which reflects the function relationship between equivalent structural stress concentrated factors and the design variables.The accuracy of the surrogate model was checked and estimated by comparing with the finite element results of another group of latin hypercube samples;on the basis of surrogate model,parametric study was conducted and the regulation of the different structural parameters’ effects on equivalent structural stress concentrated factors was revealed;4)Regarding the minimum mass of the whole girder as the objective function,and fatigue performances,bending stress,shear capacity,and the whole stability of the girder were considered as constraints,the optimal model of trapezoidal corrugated web girder was established;a general integer nonlinear constraints optimal solving method and genetic algorithm were combined as a strategy of solving the optimal model,in order to enhance the speed of calculating and guarantee a global optimal result.