Concrete Railway Pier With Low Reinforcement Ratio Seismic Performance Test And Analysis

With the development of our country’s railway construction,the theory of railway bridge design has been continuously improved.However,due to historical reasons,concrete gravity piers with a low reinforcement ratio of less than 0.5% are common in our country.Based on the current research of low-reinforcement ratio bridge piers at home and abroad,this paper selects actual engineering low-reinforcement ratio gravity piers,designs and produces scaled models based on structural similarity theory,and uses a combination method of shaking table test and finite element simulation,analyzes the seismic performance of low-reinforcement gravity piers.The main contents of this article are as follows:(1)Search for journals and papers that study the seismic performance of low-reinforcement gravity piers,review the current research status of gravity piers and shaking table tests at home and abroad,and summarize various parameters that affect the seismic performance of the piers.(2)According to the theory of structural similarity,a reduced-scale concrete pier model with longitudinal reinforcement ratios of 0.2% and 0.5% was designed and produced.Through shaking table tests,the damage characteristics of the pier under real earthquakes were simulated.Then analyze the structural dynamic response under different earthquake peak accelerations,and evaluate the seismic performance of the bridge piers.The results show that the specimen can still ensure good seismic performance under the action of a rare earthquake at 7 degrees;the specimen with a reinforcement ratio of 0.2% has a through crack at the bottom of the pier body when it is destroyed,with low ductility and obvious brittle failure characteristics.The specimens with a reinforcement ratio of 0.5% have a larger distribution of pier cracks,good ductility,obvious plastic hinges,and ductile failure characteristics.(3)Establish the finite element model of two scaled bridge piers based on OpenSees,calculate the acceleration and relative displacement time history curve of the pier under different working conditions,and compare the difference between the shaking table test and finite element calculation.The results show that the time history curves of the shaking table test and the numerical simulation are in good agreement,which verifies the validity of the numerical simulation.(4)Through OpenSees,the curvature and displacement incremental dynamic analysis of specimen models with different reinforcement ratios are carried out.For low reinforcement ratio concrete piers,the increase of reinforcement ratio can significantly improve the ductility of specimens;under different working conditions,the structure is in the elastic deformation stage before yielding,the curve similarity is higher,and the degree of dispersion is small.After structure yields,the curves under different working conditions begin to separate,and the greater the reinforcement ratio,the separation phenomenon is more obvious;0.2～0.3% reinforcement ratio will fail faster after the structure is broken,and the ductility will be limited.The specimens with a reinforcement ratio of 0.3% to 0.5% still have obvious ductility after failure;compared with the design codes,concrete piers with a reinforcement ratio of 0.2% to 0.5% can meet the seismic fortification requirements under 7-degree earthquake.