Seismic Performance Evaluation Of In-service Curved Beam Bridges

Curved beam bridge is widely used in urban grade separation bridge because of its function and appearance.Due to the long service life,some bridges can not meet the requirements of the earthquake,and the seismic performance evaluation is needed.In this paper,a three-span continuous curved beam bridge with a radius of 55 m is used as the research object.The seismic response of the bridge under the low frequency ground motion and the high frequency ground motion is analyzed.The appropriate seismic damage model is used to analyze the damage of bridge components and overall structure.Based on the bridge test results,we take the carrying capacity calculation coefficient to modify the damage index of each component of bridge,and evaluate the seismic performance of bridge components and overall structure.The specific research results are as follows: Result oneExcept the main girder didn't crashed in the small earthquake corresponding to the high frequency earthquake,the other main girder has occurred different degree of collision,and in the large earthquake of low frequency earthquake,the main girder has a slight damage.In other cases,although the main girder has crashed with adjacent coupling girders or blocks,the main girder is still in a basic state.Result twoExcept bearing is keeping basic integrity in the small earthquake corresponding to the high frequency earthquake,the other bearing has occurred different degree of damage,and in the large earthquake of low frequency earthquake,the bearing is the most serious,part of the bearing has been completely damaged.Compared to the different degree of damage of the bearing in every earthquake,the bearing in the low frequency earthquake is more serious than the bearing in the high frequency earthquake.Result threeExcept each bridge pier is less damaging in the small earthquake corresponding to the high frequency earthquake,the pier had a more serious damage in the other different intensity seismic action,and the pier has been completely destroyed while the bridge collapsed in the large earthquake of the low frequency earthquake.In other cases,the pier has undergone moderate damage or serious damage.Result fourComparing the extent damage of the curve beam bridge under every seismic actions,we can draw a conclusion that the bridge structure damage in the low frequency earthquake is more serious than it in the high frequency earthquake.With the increase intensity of the earthquake ground motion,the earthquake response of the bridge structure is more significant and the degree of damages increased.Result fiveThe destruction of the bridge structure is the result of the cumulative damage of each component.The damage of any component will affect the safety of the whole structure,and the damage of the bearing and the pier will have a great influence on the damage of the overall structure.The damage condition of the bridge pier will be decisive to the damage degree of the bridge effect.Result sixBy taking the carrying capacity calculation coefficient Z1 to modify the damage index of each component of bridge,which can make the bridge damage and the seismic performance evaluation result more realistic.