Seismic Performance Evaluation And Reinforcement Of The Concrete Girder Bridge Based On Pushover Analysis

As an important part of transportation, bridges play a key role during earthquake relief. Once the bridge damaged during earthquake, it will bring great negative impact to not only traffic, but also to the earthquake relief and recovery efforts after the earthquake. There are a large number of bridges in China. Many of them are concrete girder bridge. At the same time, a lot of damage experiences show that this type of bridge structure is fragile in earthquake. Therefore, it is necessary to evaluate the seismic performance and reinforce the concrete girder bridge.Capacity spectrum method based on pushover analysis is commonly used for assessment of seismic performance. This paper firstly analyzes the characteristics of seismic analysis of bridge structure based on the principle of pushover method. The effect factors, such as foundation flexibility, lateral load pattern are deeply studied. And the influence of pier high to the result of pushover analysis is contrasted. Then calculating the demand spectrum based on the Guidelines for Seismic Design of Highway Bridges in China. The aseismatic performance of piers in different height is studied. Practical evaluation of lateral seismic performance is conduct on a concrete continuous girder bridge and analysis the influence of bridge layout scheme. Seismic evaluation reinforcement and re-evaluation is also carried out for a single pier. Through the above analysis, the following conclusions were reached:1. The foundation flexibility has important influences to bridges; the implement of foundation flexibility effects will be able to extend the natural vibration period, change the vibration mode and make the calculation of modeling more accurate.2. Lateral load pattern has certain influences to pushover analysis. For structures with simple form and higher first-order vibration mode, only considering the role of first-order mode is sufficient to get accurate results. For structures with complex form and lower first-order vibration mode, it's not adequate to consider only first-order vibration mode. The influences from higher modes should be considered.3. The influences of height-diameter ratio of piers to lateral seismic performance for continuous girder bridge are relatively large. With the increase of ratio, the vibration of bridges is more and more irregular. The overall seismic performance will be decrease. Under this condition, optimizing the stiffness of the piers should be conducted to get accurate result.4. It can improve the seismic performance by the means of evaluation, reinforcement and re-evaluation based on the pushover analysis.