| The precast segmental construction technology has many features,such as little impact on existing traffic and surrounding environment,high comprehensive economic benefits and short construction period,thus has obvious advantage in the construction of cross-sea and cross-river bridge.The precast segmental construction technology has always been used in bridge upper structure.The lack of study on seismic performance of precast segmental bridge piers in high seismic area limits the application of the precast segmental piers construction technology.Based on this background,the paper reveals the seismic response characteristics failure mechanism and collapse mode of precast segmental double-column piers by the shake table test and finite element analysis.The effects of different design parameters on seismic performance influence rule is studied and provided basis for seismic design and engineering application of precast segmental double-column piers.The main work are as follows:(1)Three double-column piers was designed in this paper,including cast-in place double-column piers,steel sleeve connection and metal corrugated pipe connection segmental double-column piers.The response characteristics of acceleration,displacement,strain,intensity and stiffness degradation,earthquake damage mechanism was studied through the shake table test.(2)The accuracy and applicability of the segment modeling and integral modeling for the numerical simulation of shake table test were compared and analyzed based on OpenSees.The effect of a series of parameters on the seismic performance of the segmental double-column piers was analyzed,such as constant axial compression ratio,ratio of longitudinal reinforcement,existing of prestressed tendon and initial tension of prestressed tendon,existing of energy dissipation steel bar and reinforcement ratio of that,existing of fluid viscous damper.(3)Two span continuous beam bridge model of cast-in-place and precast segmental double-column piers were built based on OpenSees and Midas/Civil.The seismic performance of precast segmental double-column piers is initially explored.The main conclusions are as follows:(1)The damage of the cast-in place double-column piers is mainly caused by the cracking of concrete in the plastic hinge region of pier bottom and top.However,the damage of segmental double-column piers is mainly caused by the destruction of the joint,and the swing phenomenon is obvious.The steel sleeve and the reinforcing steel bar,the corrugated pipe and the steel bar are connected reliably,and both of them have no relative displacement.Compared with cast-in place double-column piers,the integral stiffness of segmental double-column piers declines more obvious and the peak displacement of pier top is larger.(2)Segment modeling method is more accurate for detail simulation,thus used for parameter influence analysis.The results show that the increase of the initial stress of prestressed tendons,the reinforcement ratio of the steel bars and the viscous dampers can significantly reduce the residual deformation and improve energy dissipation capacity and the integral stiffness of the segmental double-column piers.The seismic performance of the segmental double-column piers can meet the seismic performance of the cast-in place double-column piers.(3)Compared with the cast-in-place double-column piers continuous beam bridge,segmental double-column piers continuous beam bridge has larger peak displacement,a certain self-reset capability after the earthquake and better seismic performance. |
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