Research On Design Parameters Of ?-shape Girder Curved Cable-stayed Bridge

Curved cable-stayed bridge is the kind of cable-stayed bridge of which the main beam is curved.It has the stress characteristics of both curved beam bridge and cable-stayed bridge.The main beam is subjected to bending moment,shear force and a great torque simultaneously.Its mechanical behavior is more complicated than the linear cable-stayed bridge with a high degree of spatiality.Aiming at the theoretical analysis and design optimization of ?-shape girder curved cable-stayed bridge,a research and analysis of the most important influence parameters of curved cable-stayed bridge i.e.the central angle(the ratio of arc length,the radius of curvature)and the rest of the more important design parameters(the position of the auxiliary pier,the ratio of tower height to span)is conducted based on the Brazzaville Riverside Avenue curved cable-stayed bridge project in Congo,with the analysis software of Midas/Civil which is special for the bridge used as the computing platform.The main contents of the thesis are as follows:1.The calculation analysis theory of the curved girder bridge and cable-stayed bridge is introduced in detail.Through the derivation of the Vlasov equation,the bending and torsion coupling effect of the ?-shape main beam is explained in order to carry out an accurate analysis of the curved cable-stayed bridge;2.By establishing the finite element model of full bridge,the calculation results and the measured data of the real bridge is compared to verify the correctness and rationality of the finite element model;3.Combined with professional knowledge and engineering practice,four design parameters which have important effects on structural force behavior of curved cable-stayed bridge,namely the position of the auxiliary pier,the ratio of tower height to span,the ratio of the arc length and the radius of curvature are selected to perform the parametric analysis.Based on the full bridge finite element model and by the way of changing the value of these four design parameters respectively,a number of finite element models are established,and then the results are compared and analyzed to obtain the influencing rule of the change of every single design parameter on the mechanical behavior of the structure and its reasonable value range.4.Based on orthogonal experimental design and extreme difference analysis method,several design parameters are optimized further.Taking four design parameters of the position of the auxiliary pier,the ratio of tower height to span,the ratio of arc length and the radius of curvature as factors,three levels of value within a reasonable range of each factor are determined.With 10 characteristic values that can be used for reflecting the whole mechanical performance of the curved cable-stayed bridge selected as the experimental indexes,the impact level of these four factors on every single index is determined by using L9(34)orthogonal table and extreme difference method.And the main factors and secondary factors corresponding to each index are obtained.What's more,the influence law of each factor on each index is obtained so as to perform a further optimization of the reasonable range of these four design factors.