Capacity evaluation of RC girder bridge with vibration testing technique

Dynamic parameters were used to evaluate the loading capability of existing RC girder bridge. According to the experimental results of damnification test on four pieces of RC simple T-beam and applying nonlinear regression analysis method, some equations expressing the relation of the stiffness ratio and frequency ratio of T-beam were obtained, a relation of the structural dynamic characteristic and bearing capacity of RC single beam was proposed. Based on the measured basic frequency and crack characteristic, the dynamic characteristic of the whole bridge was divided into the dynamic properties of single beams. So the model of dynamic assessment was expressed, structural basic frequency and crack characteristic→rigidity→nominal ratio of reinforcement→resistance to bending of single beam. In the dynamic assessment of a actual RC simple bridge, the deflection-controlling bending moment, crackcontrolling bending moment and intensity-controlling bending moment of single beam are obtained, the evaluation result of vibration method is accurate and accordant to static test result, which indicates that the frequency and crack characteristic can be used to forecast the loading capability of existing RC girder bridge. 3 tabs, 9 figs, 9 refs.