| Double-column and multi-column piers are commonly used in highway bridges and viaducts.Under the action of earthquakes,these piers would be subjected to complex bending-shear-axial force coupling,and they have been severely damaged during previous earthquakes.In this paper,the seismic performance of irregular double-column piers and three-column piers was studied by numerical simulation method.For the irregular double-column piers,a hybrid seismic system was proposed,in which the short pier was designed as rocking self-centering structure.In addition,the seismic characteristics of three-column bent piers with tied beams were paid attention to.The main content and understanding of this paper include:1.The current research progress on seismic performance of bridge bents was summarized by consulting domestic and foreign literatures.The development process,experimental research,numerical analysis and practical engineering application of the rocking self-centering system at home and abroad were summarized.2.Based on the Open Sees numerical simulation platform,the modeling method for seismic analysis of bridge piers was proposed,and the accuracy of the method was verified according to the existing experimental results.It provided a reliable means for subsequent study for the seismic performance analysis of double-column and three-column piers.3.For the irregular double-column piers with large difference in height between the two piers,the concept of hybrid seismic system was proposed.The low pier was designed as a rocking self-centering structure to reduce its earthquake damage,and the high pier still adopted an integral type.In order to verify the seismic performance advantages of the system,a seismic numerical analysis model of the irregular double-column pier using the hybrid seismic system was established.The seismic performance of the hybrid and ordinary double-column piers was compared.Quasi-static and dynamic time-history analyses of two types of double-column piers are completed.The results showed that the method of rocking self-centering design was adopted at the short pier,which could effectively reduce the lateral stiffness of the short pier and the seismic force it bears.Under the action of earthquake,high piers played the role of compensating the force of short piers,so that the force distribution of the structure was more reasonable.Although the hybrid seismic system increased the deformation of the irregular double-column pier and increased the damage of the high pier,the residual displacement of the pier was much smaller,which effectively avoided the risk of shear damage of the irregular double-column pier and improved the its seismic performance.4.The seismic performance of three-column bent piers was studied by numerical analysis,and the axial compression ratio,hysteresis curve,plastic hinge formation process,and sectional curvature ductility coefficient of each pier were analyzed.The study showed that the axial compression ratio of side column pier changes significantly,with a variation of 36.3%;the horizontal bearing capacity of the three-column bent pier was increased by 65.0% by setting the tie beam,and the tie-beam always appeared plastic hinges first,when the three-column pier was loaded in one direction.Three-column piers with tied beams,the curvature ductility coefficient,maximum displacement angle,and residual displacement angle of the side pier section were smaller than those of three-column piers without tied beams.The tied beams could effectively protect the pier body and consume part of the earthquake.energy. |
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