Study On Reasonable Design States And Dynamic Characteristics Of Extradosed Cable-stayed Bridges

The stiffness of beam of Extradosed cable-stayed bridge is relatively greater than cable-stayed bridge whose mechanic characteristic lies between continuous beam bridge and cable-stayed bridge,In currently the cable tensions optimization for the extradosed cable-stayed bridge used the methods for cable-stayed bridge and did not apply perfectly to the Extradosed cable-stayed bridge. The paper tries to put forward a set of new suitable methods for cable tensions optimization based on researching the relative optimized theroy and methods profoundly for the extradosed cable-stayed bridge and recommendations about aseismic design for it.First, The paper puts forward a set of methods:global tension optimization adjusts the cable force behind the beam force states due to dead load of original completed bridge,then adopts influence coefficient method based on constructing and completed stage.It solved the phenomenon that the moment of girder is reasonable basically,but the prestress exceed the standard.Second,the paper puts forward a method determining the initial tension force of stay cable:Forward iteration method based on finite stages reversed disaseembly,and presents an Iterative equation.Comparing with the simple Forward iterative method,reverse dissseembly method and Forward-reverse disassembly method,it could save a lot of computation stages and time,with unstressed state method,it is not necessary to ensure the unstressed vurvature of girder continuous,and adjust the force of stay cable before beam closure.Because the equation have no explicit of reverse dissambly steps,so it is no necessary to dedicate relative software.The method is proved that it owned fast convergence efficiency and higher accuracy.Third,a links mode about pier,tower and girder is introduced based on comparing with dynamic characteristics of different mode.It presents a reference for long span extradosed cable-stayed bridge.