The Research On Optimization Technology For Steel Deck Pavement On Large-Span Steel Box Beam Bridges

The bridge deck pavement system is very important to the service performance and service life of long-span steel box girder bridge.Based on the disease analysis of steel deck pavement and relying on a long-span steel box girder bridge,the performance evaluation method of bridge deck pavement system,the sensitivity of influence parameters and the optimization of the pavement system were studied.The main contents and achievements are as following:(1)Based on the analysis of the diseases of long-span steel deck pavement,the performance evaluation system of steel box girder deck pavement with pavement quality index as the evaluation target has been established,and the weight values of each sub-index in the evaluation system are determined by Delphi method.The quality of bridge deck pavement relying on the project has been evaluated,and the evaluation results are consistent with the engineering practice.(2)Taking the long-span steel box girder bridge deck pavement system with longitudinal diaphragm as the research object,the whole bridge finite element model has been established by using the whole-local analysis method.On this basis,a locally refined finite element model has been established.By utilizing two-wheel loading mode,the variation rules of five control indexes such as maximum transverse tensile stress under 25 different load positions were analyzed,and the most unfavorable load positions of each control index were obtained.The sensitivity of 8 influence parameters such as steel bridge deck thickness to each control index has been analyzed.The results demonstrate that the thickness of the mediastinal plate is less sensitive to the control index,and the other seven parameters such as the maximum transverse tensile stress are more sensitive to the control index.(3)On the basis of sensitivity analysis of the single parameter,in addition to the thickness of mediastinal plate,the orthogonal test was designed with the other seven parameters as factors.The finite element model was used to calculate the surface maximum transverse tensile stress,maximum deflection and interlaminar maximum shear stress of each group of tests under the most unfavorable load position.The primary and secondary order of the sensitivity of 7 different parameters to each control index has been analyzed by intuitive analysis method.It is found that the optimal combination of parameters for different control indexes is not consistent.From the point of view of system engineering,a relatively optimal design scheme should be obtained through global optimization.(4)A multi-objective optimization method of long-span steel box girder bridge deck pavement system based on agent model and fast non-dominated sorting genetic algorithm(NSGA-Ⅱ)was proposed.The agent model of bridge deck pavement system has been established.The multi-objective optimization calculation was carried out by using NSGA-Ⅱ,the Pareto solution set was obtained,and the threshold method was used to deal with the value of each optimization objective function,so as to get the optimal solution.The results show that the mechanical performance of the pavement system is changed and the total weight per unit length of the pavement system is reduced after the optimization of design parameters,which proves the feasibility of the application of this method to multi-objective optimization.