Research On The Optimization Theory Of Continuous Rigid Frame Bridge

Continuous rigid frame bridge has the characteristics of continuous bridge and T-type continuous rigid frame bridge, reasonable stress, well-formed, comfortable driving conditions. At the same time, it has the advantages of lower cost, construction method of mature, larger spanning ability and adaptable to topographical and geologci-al conditions; it has been widely used in the actual project. For a long time, the design of continuous rigid frame bridge mainly depends on experience and structural computation. So it is necessary to optimize the parameters of continuous rigid frame bridge, Based on static optimization and dynamic optimization. At present, in the optimization study of continuous rigid frame bridge, variables selection is not comprehensive, optimization objective is singly, constraint condition is not clear and the selection of optimization algorithm with random. Aim at the above-mentioned problems, the main work is summarized as follow:(1) In the parameters of continuous rigid frame bridge sup structures, abutment span ratio, high-span ratio at root of the beam, high-span ratio at central of the beam, beam bottom curves of power,divided of segments and prestressing tendons along the bridge as optimization variables, while the rest of design parameters can be considered as optimal constant. In the parameters of continuous rigid frame bridge sub structures, pier’s size along the bridge, distance of thin-wall pier and thickness as optimization variables and the rest of design parameters can be considered as optimal constant except the ratio of its piers.(2) In order to analyze the stressing influence of large-span continuous rigid frame bridge if the height of its double thin-wall piers were not equal, one bridge in construction is calculated. The result showed double thin-wall piers of bridge were not equal, the superstructure of bridge is affected insignificant, and the internal force of piers was affected greatly. The ratio of pier’s height should be as optimization variable if pier’s height is restricted by topographical conditions.(3)In static condition, take uniform stress distribution, minimum stress and cost as optimization objectives. Under seismic action, according to whether considering the cumulative damage, made of the ratio of actual effect and the allowable maximum effect and seismic damage indices as optimization objectives.(4) Under static load, the constraint Conditions is the stress of construction and using. In the earthquake, take the range of value, ratio of actual effect and the allowable maximum effect and seismic damage indices, as constraint conditions.(5)Based on a continuous rigid frame bridge, the seismic damage index is calculated.(6)Present two ways to selecting optimization algorithm, the first way is establishing test model for optimization problem, and the second way is based on the advantages and disadvantages of various optimization algorithms, Establish hybrid optimization algorithms.