The Seismic Design Theory Of Irregular High-pier Bridge In Mountainous Areas

As a lifeline, bridges are playing an increasingly important role in today's economic construction. There are a lot of secondary disasters will be caused by the bridge damage in the earthquake. So we will suffer heavy losses from the two aspects of social and economic. As a structural engineer, we have the responsibility to find a reasonable design method to reduce the loss of earthquake damage. In this paper, we can get some conception about the bridge construction in the western mountain districts. According to the characteristics of the bridge, we can sum up some method about the conceptual design of the mountain bridge. Then, we focus on the seismic design methods based on displacement which are very popular nowadays.What the most important problem to use the seismic design methods based on displacement is how to calculate the displacement demand. Though many ways we can get, mostly there is a certain degree of approximation in the ways. And different methods may have different implementation process. In this paper, we selected a special case of the calculation of displacement demands about SDOF systems-such as two calculation methods have the same displacement. Generally speaking, the period of vibration of high pier system is very long. But we can't approximate it as a single-particle system, because it has large height and weight. So we should test and verify if the method can be applicable in Multi-degree of freedom system (MDOF).In this paper, SAP2000was used in this study. The pier having different height and sectional diameter should be calculated in two ways-the multi-modal elastic-plastic push-over analysis (MPA) and elastic response spectrum analysis. Then, the results of the two calculation methods should be compared with each other. The conclusion is that the two results are nearly identical. So the elastic-plastic push-over analysis and elastic response spectrum analysis have the same displacement. We can use this conclusion to seismic design of bridge in the future.