Preliminary Design Study Of Long-Span Cable-Truss Bridge

A new type bridge named long-span cable-truss bridge(LSCTB) was created which can combines advantage of cable and truss structure. The bridge researched in this paper has same length and width as Jiangyin Bridge.Static and dynamic optimum analysis were done using first-order method. Nonlinear mathematics model with constraints was made. The minimum global cost of bridge was selected as goal function,Design variables were selected as much as possible in order to find out the main factors affecting characteristics of LSCTB,Displacements,structure stress and dynamic characteristics were used as constraint variables. Conclusion was drawn that static and dynamic characteristics were improved greatly comparing to Jiangyin Bridge.A new kind of theory and calculating method which is suitable to cable supported bridges was developed in this paper. Cable element can include the structure's geometry nonlinearity and initial stress,Virtual laminated element has high calculating efficiency and good precision.Dimensions of LSCTB was put forward based on conclusions of optimum analysis. Development of load code and controlling load condition were discussed,Detailed analysis of cable-truss,bridge tower,stiffening girder and anchorage was done which proved that LSCTB is a competing bridge type.How to model stiffening box-girder is a difficult problem for a long time,Virtual laminated plate element method which put forward in this paper is a powerful tool to solve the problem. This method has high efficiency and precision comparing to traditional method. Dynamic analysis of this bridge showed that the bridge's seismic response was small and flutter critical wind speed was improved to a high level.