Force Analysis Of Asymmetric Continuous Rigid Frame Bridge

When building a continuous girder bridge in the mountain area with rugged terrain, the amount of piers will increase. As a result, the total construction cost will rise. Moreover, if the cantilever construction method is chosen, the amount of provisional anchorage devices will increase, which will also arise the construction difficulties. In this case, a continuous rigid frame bridge is preferable with its large span capacity and its convenience in the construction process where it requires no system conversion. Normally a continuous rigid frame bridge is arranged symmetrically. However, in some cases such as an unfavorable topographic condition or a restricted navigation condition, an unsymmetrical arrangement is usually selected. Generally, there are two kinds of unsymmetrical continuous rigid frame bridges regardless of curved ones:the one with unsymmetrical longitudinal spans, and the one with piers having height differences. And in the practical projects, there are those with both features mentioned above. Under load action an unsymmetrical continuous rigid frame bridge will have unsymmetrical internal forces and deformations, which is different from symmetrical ones. Therefore, it is necessary to study on unsymmetrical rigid frame bridge. Based on project of western region a very good application examples of asymmetric continuous rigid frame—the Yantou River Bridge in Sinan county in Guizhou province, an analysis on unsymmetrical continuous rigid frame bridge is carried on with the help of finite element program. Several aspects studied in this paper are as follows.(1) Set up a finite element model of a continuous rigid frame bridge with unsymmetrical longitudinal spans. Keep the three parameters of pier of one side, including the height, the width in the longitudinal direction and the spacing of double thin-wall, and change those three parameters of the other side. Then compare and analyze the internal force and deformation of piers under load action. By that, features of internal force and deformation of continuous rigid frame bridge with both unsymmetrical spans and different pier heights can be acquired.(2) Set up another finite element model, a continuous rigid frame bridge with symmetrical longitudinal spans. Keep the height of pier of one side, and change the height of pier of the other side. Then compare and analyze the internal force and deformation of piers under load action and try to find out the characteristics of internal force and deformation of continuous rigid frame bridge with symmetrical spans but different pier heights.(3) By contrast and analysis of the layouts of tendons of an unsymmetrical rigid frame bridge (The Yantou River Bridge) and a symmetrical rigid frame bridge (The Second Wujiang River Bridge), draw some conclusions on their similarities and differences. Analyze the location differences of mid-span tendon's control section of symmetrical and unsymmetrical rigid frame bridge and find out the variation trends of mid-span tendon's control section of unsymmetrical rigid frame bridge.