Experimental Study On Seismic Performance Of UHPC Double-limb Thin-walled High Piers

In continuous rigid frame bridges,thin-walled high piers with two limbs are widely used in bridge construction in mountainous areas because of their small longitudinal thrust stiffness,which can effectively solve the problem of deformation coordination between piers and beams.At the same time,ultra-high performance concrete has ultra-high compressive strength,toughness and durability.If ultra-high performance concrete is applied to the thin-walled high piers of the two limbs,it will provide a new idea for the design of flexible piers for the realization of bridges of 400m or larger.Based on the experimental study on the seismic behavior of ordinary reinforced concrete thin-walled high-rise piers,an innovative high-performance concrete(UHPC)double-limb thin-walled high pier is proposed.Then the seismic performance of the finite element software was compared by the pseudo-static test and the finite element software.The main work and conclusions of this paper are as follows:(1)Based on the premise of the bridge structure test method,the similar relationship between strain,displacement and stress of the pier model under concentrated load is obtained according to the dimensional analysis method.Taking the main pier of Zhangjiajie Taijixi Bridge as the research object,a large proportion of ultra-high performance concrete double-limb piers(UC-1)and two ordinary reinforced concrete double-limb piers(RC-1,RC-2)were designed and manufactured.Scale model.The production process,pouring method and curing process were introduced in detail.The loading scheme of the test was also explained in detail,and relevant data measurement methods were developed.(2)Consider the pseudo-static test of these three test piers under the action of constant axial force.The failure characteristics,hysteresis curve,displacement ductility,stiffness degradation characteristics and energy dissipation performance of the test pier were obtained after applying low-cycle repeated load to the test pier.The results show that the failure modes of the two types of piers are similar,but when using ultra-high performance concrete,the ductility performance,energy dissipation performance and deformation capacity of the pier can be greatly improved.(3)The test pier is analyzed by ABAQUS finite element software.The error between the numerical simulation results and the test results is within a reasonable range,and the trends of the two are consistent.The finite element model and its analysis method established in this paper can better reflect the seismic performance and failure characteristics of UHPC double-limb piers under low-cycle repeated loading.(4)The design parameters of UHPC double-limb piers are discussed.The research shows that the seismic performance of a pair of beams at the height of the pier is the best.Selecting the appropriate limb thickness and the distance between the two limbs can effectively improve the seismic performance of UHPC double-limb piers.