Seismic Performance Improvement And Analysis Of Partial Cast-in-place Prefabricated Segmental Bridge Piers

With the gradual promotion of the concept of assembly construction,prefabricated components and construction mode have been more and more engineering applications.As a kind of prefabricated structure,precast segmental pier has the advantages of construction speed,easy to reconstruct and repair after disaster.However,considering its sway system has obvious characteristics and its structural integrity is relatively low,it is necessary to study the mechanical behavior,especially the seismic performance of the structure.Based on partial cast-in-place system pier which is accepted in engineering,this paper adopts the numerical simulation method which can meet the needs of multi-result parameters to systematically study the seismic performance of prefabricated segmental piers.Main work of this paper includes:1)Systematically summarized and analyzed the necessary and key aspects of the model that analyzed in this paper on the basis of seismic performance and its improvement,including: described and analyzed the structural and mechanical characteristics of precast segmental piers;studied the improvement mechanism and engineering measures of existing precast segmental piers at home and abroad;focused on analyzing the stress and deformation characteristics of pier structure in different stages of bending failure;determined the proper proportion of pier bottom of partial cast-in-place system precast segmental pier.Besides,the capacity of shear of verification model that mentioned in following content is checked,and the failure mode of pier is determined.2)Described in detail the method and process of solid modeling of reinforced concrete on the basis of ABAQUS software and based on the concrete constitutive relationship,the plastic damage model is used to calculate the appropriate tensile and compression control damage factor.The Finite element model which is equivalent to the test pier in the literature is established for verification calculation.Thus,the hysteretic curve obtained is consistent with the experimental study in literature.It proved the rationality of the calculation method.On this basis,the influence of the location of unbonded prestressed steel bars on the characteristics of hysteretic behavior of pier is studied.3)On the basis of partial cast-in-place system,five representative improvement scheme for seismic performance of pier are proposed,which are built-in steel bar type,mortise and tenon joint type,restraint reinforcement type,restraint connection type and external damper type.Combined with the above work,the finite element analysis models are established respectively.Two simulation loading methods,monotone push and reciprocating loading,are adopted.Considering the ultimate bearing capacity,ductility coefficient,cumulative energy dissipation capacity,residual displacement and other main seismic parameters,the seismic performance of each model is systematically analyzed and summarized.The main results show that: compared with the original model,improved model has been discovered a great improvement in the seismic parameters,while maintaining the self reset ability of its own swing system structure.Considering the different load sizes,the law of the seismic performance of each improved model changing with the load has been further explored.As for the improvement scheme of pier that with external dampers,dynamic time-history analysis method has been adopted to obtain the response values of displacement and acceleration of pier top under different seismic waves.The improvement of its seismic performance have been determined by comparing with the response values of the original model.