Parameter Optimization And Stability Analysis Of Rigid Frame Bridge Of Long-span Continuous

As the highway and railway construction gradually transformed to the Western region,long-span continuous rigid frame bridge has become a competitive choice,for the reason of its hypsographic feature and economic principle.The value of bridge parameters can greatly affect the internal force state,however,they are often chosen by experience in actual bridge design,so it has great contingency and blindness.The bridge parameters are also directly related to structural stiffness,thus influencing the stability of the rigid frame bridge.But the research results in this field are relatively less,in which the single variable method was adopted without considering coupling effect of the parameters;therefore,it is necessary to carry out a thorough study.In the engineering background of Daduhe Bridge,the parameters such as ratio of side to main span,ratio of rise to span,parabola power of beam bottom,net distance between two piers,were selected as key design parameters.At the same time concrete amount,bending strain energy and stability coefficient was taken as objective function.After that,the parameter optimization and stability analysis of continuous rigid frame bridge were performed using finite element model method software Midas Civil and MATLAB computer codes.The main research content was summarized as follows:(1)The research status on this subject both at home and abroad was organized;the theory of particle swarm optimization algorithm was also introduced in detail.Meanwhile,the two kinds of questions of stabilizing were explained in essence.(2)Response surface methodology and Latin hypercube sampling were first introduced to bridge structural optimization so as to take account of the coupling effect of the parameters.The contradiction problem between the total weight of truss structure and stress was solved by calculating its optimal diameter,thus the efficiency of this optimization algorithm was validated.(3)The range of values of each parameter was summarized on the basis of arrangement of long-span continuous rigid frame bridge around the world.The weight coefficient of each objective function was also given in this paper.After that,the response surface model of comprehensive function and optimal parameters was built by the methods mentioned above.Using this model the optimization iteration was carried out,the optimal parameter combination was also obtained.In this way,the efficiency of this project has been greatly improved.(4)The performance of bending moment,deflection,section stress,concrete quantity and shear force of the four key sections are compared with its original state.The conclusion that the mechanical properties of the optimized structure have been ameliorated considerably was drawn,and the character that internal force distribution behaves more uniform was obtained too.(5)By studying the stability of construction process before and after optimization,the variation of stability coefficient was gained.Then the nonlinear stability was analyzed by considering the nonlinear effect.And the influence of structural damage to stability was researched by elastic modulus’ reduction.In the end,the optimal kind of concrete was calculated,meeting the requirement of minimum of cost and stability,by fitting the curve of stability and concrete types.