Study On Seismic Performance Of Reinforced Concrete Bridge Piers With CFRP Composite Reinforcement

As an important part of modern transportation system,bridge is very important to ensure that the lifeline after earthquake is unimpeded.However,under the action of earthquake,the bridge is a weak link.As a vertical load-bearing and horizontal force-resisting component,the stress condition of the bridge pier is more complex.Moreover,the bridge short piers have high stiffness and are prone to occur brittle bending shear failure or shear failure.Besides,there are a large number of old bridge piers with insufficient seismic performance also have safety problems.At present,the damaged bridge piers can be treated by dismantling and rebuilding or repair and reinforcing,but the former has problems such as high economic cost,long construction period,and causing waste of resources easily,while the latter does not have the above problems.In addition,the traditional single reinforcement method has some limitations,and the improvement of seismic performance of the bridge pier is limited.However,the composite reinforcement method can make up for its limitations,but there are few related studies.Therefore,it has important theoretical and practical significance to study the composite reinforcement method of bridge piers.Based on this engineering background and research significance,this paper takes reinforced concrete bridge piers as the research object,and conducts research on the seismic performance of CFRP composite reinforced bridge piers through the method of experiment-based and numerical simulation-assisted.The main contents are as follows.(1)Firstly,the existing bridge pier reinforcement methods are summed up,and the existing research problems are summarized.On this basis,combining the material properties of CFRP,steel wire and steel jacket,composite reinforcement technologies for bridge piers under the combination of CFRP-steel wire and CFRP-steel jacket are proposed.(2)Secondly,in view of the two CFRP composite reinforcement technologies,the test plan is formulated.Then three reinforced specimens and two unreinforced comparison specimens are designed and made.After the pre damage of reinforced,CFRP,CFRP-steel wire,and CFRP-steel jacket are used to repair and strengthen the specimens.Subsequently,the specimens are repeatedly loaded to failure in low cycles.The test results show that the three reinforcement methods will not increase the cross-sectional area and initial stiffness of the bridge pier,and will not affect the shear force distribution under earthquake action.CFRP reinforcement can effectively improve the failure mode,enhance the ductility and energy consumption capacity,and delay the stiffness degradation of the bridge pier.However,due to the serious damage of bridge pier concrete,the CFRP is easy to crack and damage.The CFRP-steel wire composite reinforcement improves the energy dissipation capacity of bridge pier to a greater extent.And the steel wire and steel jacket can effectively inhibit the cracking of the CFRP and the damaged peeling of concrete.At the same time,they can be used as a safety reserve for the earthquake resistance of bridge pier.CFRP composite reinforcement method has obvious advantages.(3)Finally,based on the finite element analysis software Open Sees,the fiber element method is used to establish the finite element model of bridge pier and carry out the numerical simulation.The calculated results are in good agreement with the hysteretic characteristics of the pseudo-static test results,such as the horizontal bearing capacity,ductility performance and strength attenuation trend.The error meets the requirements of engineering accuracy.