Study On Rational Structural States And Wind-resistance Performance Of Cable-stayed Suspension Bridges

The cable-stayed suspension bridge is a kind of bridge which combines the main components of the the cable-stayed bridge and suspension bridge and takes use of the advantages of the two types of bridge.At the same time,it has greater span capacity and windresistance.In recent years,with the continuous progress of the design and construction technology of large span cable bearing bridge,as well as the increasingly complex bridge site environment,this type of bridge has gradually attracted the attention of domestic and overseas experts and continues to move towards a larger span.Compared with cable-stayed bridge and suspension bridge,there are many differences in the the analysis methods of design and windresistance of cable-stayed suspension bridge.Therefore,it is necessary to carry out systematic research to provide theoretical support and supply advice for the popularization and application of this bridge.In this paper,cable-stayed suspension bridge are taken as the research objects.The following prospective works are carried out by employing theoretical analysis and numerical simulation methods:(1)The calculation method of reasonable completed state of cable-stayed suspension bridge is studied in this paper.The main cable shape of the main span and side spans of the cable-stayed suspension bridge is calculated by using the segmented catenary theory.Based on the finite element method and using the double iteration method,the nonlinear effect of cable force variation of large-span bridge is considered.Then,the function relationship between the cable force and bending strain energy of the tower and girder structure is established.The nonlinear programming theory is used to solve this function and the cable force optimization is realized.In addition,the distribution ratio of cable force and hanger force at the joint area is also contrasted.(2)The reasonable construction condition of cooperative system bridge is studied.Based on the characteristics of repeatedly tensioning in the construction process of cable,a multiobjective optimization method of cable force during construction is established,and a computation program of reasonable cable force during construction is designed,aiming at safety performance and convenience of closure.The characteristics and advantages of two alternative schemes in cantilever construction are analyzed and compared,and the timing of the completion of the main cable and the closure position of the main girder in the joint area are compared.(3)The aerostatic stability of the cable-stayed suspension bridge is studied.Based on the finite element method,the critical wind speed and instability mode of aerostatic stability are calculated by the incremental double iteration method,with optimum iteration.The influence of different parameters on the aerostatic stability of the cable-stayed suspension bridge is analyzed.The results are compared with those of the cable-stayed bridge and suspension bridge with the same main span.(4)The flutter stability of the cable-stayed suspension bridge is studied.The critical flutter wind speed and flutter mode are calculated by the full mode method.The influence of different parameters on the flutter stability of the cable-stayed suspension bridge is analyzed.The results are compared with those of the cable-stayed bridge and suspension bridge with the same main span.