Model Test Study Of Concrete Arch Bridge With CFST Stiffened Skeleton

The under construction Beipanjiang super-large bridge in the Hu-Kun passenger-dedicated railway line is a concrete arch super-large bridge with CFST stiffened skeleton with span of445m. The main bridge is constructed with the stiffened skeleton method. The stiffened skeleton of steel tube is set up at first. Then the outer-packed concrete of the arch box is cast relying on the support of the stiffened skeleton. The concrete in composite section of Beipanjiang main bridge arch ring is cast by longitudinal segments and transverse loops. The construction process goes through many times of system conversion, and structure’s stiffness and strength gradually come into being. Therefore the mechanical behaviors of the arch ring are extremely complicated. In order to study its mechanical characteristics and deformation patterns, a research of main bridge arch ring’s model test with scale of1:7.5was carried out. The research contents and outcomes are as follows:(1) The similarity theory used in model test was introduced at the beginning. Then with an illustration of practical examples, three derivation methods of similarity criterion were listed. The general process of model test was presented afterwards.(2) By use of dimensional analysis method, the similarity conditions were derived in the thesis. With the basis of similarity conditions as well as the actual conditions at test site, the test model was designed, including the geometric scale, test materials, model structure and dead load compensation device.(3) According to the local conditions, the overall construction and loading process were introduced. During the model test, the critical construction process was simulated, and a series of counterweight was placed to compensate the dead load. The stress and displacement were measured at each loading state.(4) The numerical simulation of the model arch ring was realized by MIDAS/Civil, a finite element calculating software for bridges. Compared with the test data of stress and displacement at different sections, the numerical analysis shows that the model arch ring has a good mechanical performance, and the design proposal can stratify the construction requirements. The construction method and sequence are reasonable and practical. The test results verify the construction security of the actual bridge and show that there is a certain extent of strength margin for the actual bridge.