Research On Dynamic And Static Load Test Of Long-span Continuous Bridge

Semi-rigid frame for prestressed concrete bridge is the main category of long-span beam bridge. Its major features is that the main beam is continuous and pier and beam are semi-consolidated. The bridge deck expansion and contraction joints are generally at 2, conducive to high-speed traffic. T-shaped rigid frame is no bearings, no system conversion and to facilitate construction . Bridge to the larger-lateral bending stiffness and torsional stiffness can be very good to meet the greater demands of the force of the long-span bridge. According to the Ministry promulgated the "Safety Work Rules for Highway Maintenance", we must identificate the bearing capacity of these bridges. However there is a certain difference between inference theory and actual structure, so identification of the carrying capacity is also inseparable from the load test currently. At the same time, as the new bridge design is often more slender soft, it make the problem of vehicles -the bridge vibration being prominent. On the one hand, the dynamic impact of the high-speed vehicles against the bridge impacts directly on the bridge work state and life of the bridge, on the other hand, the vibration of bridges impacts on the smooth and safety of vehicles, so load test is necessary. Bridge load test is the most direct and effective ways and means to evaluate the quality of the bridge. Such bridges load tests help to promote such bridge design theory and the development of the theory test.In this paper, we did the static and dynamic load test of Liang Ji Canal Bridge. We have a comprehensive analysis of the semi-rigid frame bridge for the strain, the change of deflection. We analysis test data from the test about mode, sports and bump using the method of time domain and frequency domain in E-Testtab software and calculate the natural frequency of bridges, the coefficient of impact and damping ratio. We made a comparative analysis between the frequency and damping ratio. And we made the comparative analysis between experimental measurements and the acceptable limit of the corresponding bridge design standards, load testing standards and comparised experimental measurements with the theoretical values. The aim of this work is to provide the basis of the study of the carrying capacity that will be applied in the future for the dimensioning of similar structures And verificated the design standard and reasonable of the existing bridge structure.Using large-scale finite element software MIDAS / CIVIL assistant established a 3-D finite element model of real bridge, including the data input of section,boundary conditions and loads , etc. The aim that internal force of the control section was calculated under the design load and tests load is to obtain coefficient of effect of load combination; The theoretical value of the strain and deflection to all the measuring points under the status of the test load was calculated and compared with the measured value; Eigenvector was calculated using a subspace iteration method in modal analysis of the bridge model in order to obtain the first two vibration mode. We can obtain the corresponding natural frequency from the first two vibration mode and calculate the coefficient of impact according to the corresponding norms. We can further verify the reasonableness of the design. The aim of doing this is to provide reference of the carrying capacity of the similar bridge using the finite element method in the future.