| Through factory precast and site assembly,the precast segmental bridge pier system can greatly shorten the construction period and effectively reduce the negative impact on the surrounding environmxent and traffic.The central and western regions are the core areas of China’s ecological construction and the typical ecological fragile areas,which provides the opportunity for the promotion of precast assembly technology.As most of the central and western regions have the requirements of seismic fortification,and there are many types of precast pier,the seismic performance of the pier is not the same when different connection methods are adopted.Therefore,the appropriate type of pier should be selected according to the seismic requirements.In order to explore the precast assembly system suitable for bridge construction in the central and western regions,this paper studies the precast segmental post-tensioned bridge columns,and studies its seismic performance and influencing factors from theoretical analysis,quasi-static test,finite element simulation and other aspects,so as to provide reference for practical engineering application.The specific research contents and results are as follows:(1)The horizontal load-displacement skeleton curve is analyzed based on the centralized plastic hinge model.According to the mechanical behavior of the pier bottom joint,the lateral deformation process of the pier is divided into three stages,using C++ language to compile the section characteristics analysis program to calculate the moment-curvature relationship,solve the horizontal load-displacement skeleton curve in stages based on the centralized plastic hinge model.The feasibility of the program is verified by the quasi-static test results,and the skeleton curve of the specimen in this test is predicted.(2)The quasi-static test of rectangular hollow-section precast segmental bridge columns is carried out.To comprehensively explore the influence of seismic performance and initial tensile force of bridge piers through the analysis of apparent phenomena and the data analysis.The results show that: Typical bending failure occurred in both groups,the damage is the crushing of the concrete core at the bottom of the pier.The hysteretic curve is a typical banner,the pier has the extremely strong self-resetting ability.The increase of the initial prestress level will increase the residual displacement,the equivalent damping ratio,and reduce the displacement ductility,the prestress loss rate and the hysteretic energy consumption,and have no effect on the plastic hinge rotation capacity and the degradation of the pier stiffness.(3)The seismic performance analysis of rectangular hollow-section precast segmental bridge columns based on fiber element.According to the joint simulation idea of equivalent plastic hinge method,the Open Sees platform is used to build an equivalent plastic hinge fiber model for prestressed segmental bridge piers,the feasibility of the model is verified by comparison with quasi-static test.Parametric analysis based on skeleton curve was carried out with the model,the effects of concrete strength,stirrup reinforcement ratio,number of prestressed tendons and constant load axial compression ratio on the seismic performance of bridge piers is discussed.(4)The seismic performance analysis of rectangular hollow-section precast segmental bridge columns based on solid element.In order to visually display the local stress deformation and displacement state of the bridge pier,ABAQUS was used to establish the three-dimensional solid finite element model of the prestressed segmental assembled bridge pier,the feasibility of the model is verified by comparison with quasi-static test On this basis,the distribution of deformation,stress and strain state of bridge piers under reciprocating loads is explored,that provides useful guidance for the stress state of the area without measuring point on the specimen in the quasi-static test. |
