Dynamic analysis of a super-long-suspension bridge based on ambient vibration test and SHMS

摘要

The boundary conditions of the suspension bridge, such as the pile-soil-structural interaction and the connection condition at the end of deck, are usually difficult to be modeled using sophisticated analytical models. So the real behaviors of the bridge remain to be verified from a full-scale vibration test. The effects of the boundary conditions on the dynamic behavior of the suspension bridge are investigated based on ambient vibration tests and its structural health monitoring system (SHMS). By taking the Runyang Bridge over the Yangtze River as example, three times of field vibration tests are conducted in different construction stages, which include the tower dynamic character tests before and after the cable installed and the full-scale vibration test of the deck. Meanwhile, a three-dimensional finite element model considering different parameters is presented and employed to sensitive analysis. The results show that soil parameters have more influence on the tower dynamic behavior than the deep length of the piles. Furthermore, the variations of the dynamic behaviors of the bridge are discussed through the comparisons of the dynamic parameters identification results from ambient vibration test with those from SHMS. Comparisons show that the first vertical mode has changed from the symmetric to anti-symmetric and that some of the lateral mode frequencies have also obvious changes. It is seen that the boundary condition has significantly influenced on the dynamic behaviors of the suspension bridge.