Test Study Of Vertical Stiffness Of Triple-tower Double-main-span Railway Cable-stayed Bridge

Abstract:Cable-stayed bridge is a flexible structure, while the railway live load is large and the requirement of stiffness of railway bridge is much higher than that of road one. The middle tower of Triple-tower Double-main-span Railway Cable-stayed Bridge (TDRCB) is easy to incline to one side because of no anchoring end cables, thus the bridge is more flexible than normal cable-stayed bridge. In this article, the problem of vertical stiffness of TDRCB was studied by means of FEM analysis and model test, taking Dongting lake great bridge (98m+140m+406m+406m+140m+98m) on new-built Jinzhou-Yueyang railway as background. The main work and results are as follows:1. Identified a1:40model scale ratio after a research of the market supply of materials, test site conditions in the laboratory, test equipment and other factors.2. A TDRCB model was designed and produced according to the similarity theory and simplified some parts of the structural members considering the operability in the actual production. It was installed in the laboratory. The testing scheme and loading devices of every test model working conditions was studied.3. The deformation and stress state of each work condition of test model was studied by establishing a MIDAS spatial model, which services for the arrangement of measuring points of the test model.4. Model test of a variety of work conditions under tow main girder stiffness,4stiffening measures were completed. The results show that: Increasing main girder stiffness can significantly increase stiffness of the bridge and reduce the ratio of deflection to span; In case of the stiffening effect of the four stiffening measures, adding horizontal stiffening cable on top of tower is the best, followed by adding stable cable on middle tower and adding one pair cross cable.5. Through comprehensive comparison of stiffening effect, construction, maintenance, repair, difficulty of cable replacement and impact on landscape, the stiffening measure of adding stable cables was recommended to Dongting lake TDRCB. The scale of this model test is large, plus the method and skill of design and production provide a reference for future similar structure test model. The research results of this paper not only provide the basis for design of Dongting lake TDRCB on Jinzhou-Yueyang railway, but also provide references for design of other similar bridge structures.93figures,24charts,75references.