| "To evaluate the seismic performance of concrete dams against large earthquake motion, much research has been done on non-linear dynamic analyses considering concrete fracture. We have also conducted research on non-linear analysis for concrete dams using the smeared crack model. Efforts to verify applicability and accuracy of such numerical analyses for concrete dams have been made through simulations for actual damages of existing concrete dams due to large earthquakes. However, there are few historical cases of damage to concrete dams and there is very little data on dam behavior during the damage process. Therefore, a more quantitative evaluation of the cracking process of concrete dams using crack analysis is needed in order to use such analytical method to estimate the limit state of concrete dams against large earthquakes. In the present study, we conducted shaking table tests on pillar-shaped unreinforced concrete specimens to investigate the crack propagation and the effect of cracks on the dynamic behavior of concrete structures. The results showed that as tensile fracture progresses, the first resonant frequency of the specimen lowers and the damping increases. We obtained a tension-softening curve from the wedge penetration type splitting test for the test material, and simulated vibration tests by non-linear dynamic analysis based on the smeared crack model. Based on a comparison of the test results and numerical simulation, we discuss how to set parameters for numerical simulation such as the tension softening curve and damping ratio, to simulate the cracking behavior of unreinforced concrete structures such as concrete dams." |
