Study On Hysteretic Parameters Identification Of Bridge Piers Based On Bouc-Wen Constitutive Model

The seismic design of bridge is widely concerned,mainly divided into two ideas:seismic-isolation design and ductile seismic design.The anti-seismic system can still achieve good effect by means of its own energy dissipation,easy replacement and low cost.For the unconventional bridge without obvious effect of high-pier.The seismic-isolation design don't apply to the grassland soil and the soft soil area,and the ductile seismic system can get better effect.The research focus of the ductile system is the pier.Based on the mid-pier of a four-span concrete continuous girder bridge,this paper establishes the Opensees numerical model and pours the concrete piers according to the ratio of 1: 2.5,and makes the low-cycle reciprocating test.Based on the Bouc-Wen constitutive model,the seismic performance of the bridge is described by studying the hysteresis characteristics of the pier.The focus of this paper is as follows:(1)Based on the existing one-sided study of structural hysteresis,this paper cites the constitutive model of smooth restoring force.The Bouc-Wen constitutive model is introduced to analyze the influence of the constitutive control parameters on the hysteresis loop,and the influence of the parameters on the hysteresis curve is analyzed.The whole process analyzes the change process by controlling the other parameters in the Opensees finite element analysis software,changing one of the parameters.(2)Using the Opensees finite element software to build a four-span reinforced concrete continuous girder bridge model,the middle pier column is selected as the low-cycle reciprocating test to draw the pier top-force curve of the pier.Based on the Bouc-Wen constitutive model,the hysteresis characteristic parameters of the original force-displacement hysteresis curve are identified by genetic algorithm.The identified parameters are brought into the original numerical model,and a new recognition curve is obtained.The two curves are put in the same frame,and the consistency of the two hysteresis loops is compared.(3)Structural hysteresis is the nature of the structure itself,without external load changes.In this paper,we change the loading system and get the low cycle reciprocating test curve.And the parameters of the curve of the parameters into the second loading conditions,to obtain a new recognition curve,and the recognition curve and the initial curve put the same map comparison,again compare the hysteresis loop fit.(4)In the physical experiment,the piers are subjected to low-cycle reciprocating,and the elastic phase,the peak stage,the bearing capacity descent stage and the failure stage are taken out respectively.The hysteresis parameters are identified and the influence of each parameter in the hysteresis curve is analyzed.(5)The Bouc-Wen constitutive model is introduced into the physical experiment.In this paper,the hysteresis curve of the pier is subjected to the parameter identification under the reciprocating load,and the hysteresis curve parameter of the pier is obtained.An earthquake is applied to the same model by the actuator to obtain the hysteresis loop of the physical test.The same seismic wave and the identification parameters in the low cycle reciprocating test are brought into the numerical simulation of the bridge model to get the numerical simulation curve of the identification parameters and compare the two curves.