Study On Seismic Performance Of Assembled Pier Connected By Grouting Sleeve

With the implementation and implementation of the concept of green highway construction in China,it is necessary to develop a prefabricated bridge structure system to adapt to the industrial construction technology of ‘factory prefabrication + on-site installation’,improve production efficiency and ensure construction quality,and reduce the environmental pollution caused by highway construction.The assembled double-column pier has good application prospects and promotion value.However,its seismic theory is not yet mature.The influence of key parameters such as the length of grouting sleeve,the diameter of longitudinal reinforcement,the position of grouting sleeve and the arrangement of pier column on its seismic performance is not clear,which seriously hinders the design and promotion of assembled double-column pier.Therefore,it is particularly important to study the seismic performance of double-column piers.Based on the actual project,this paper studies the anchoring performance of grouting sleeve specimens and the seismic performance of assembled double-column piers through laboratory tests and numerical simulation.The difference of seismic performance between assembled piers and cast-in-place piers is analyzed,and the influence of grouting sleeve length,longitudinal reinforcement diameter,grouting sleeve position and pier column arrangement on the seismic performance of assembled piers is further studied.The main research contents and conclusions are as follows :(1)The manufacturing process and test scheme of three groups of grouting sleeve specimens were designed and developed.The stress-strain relationship of grouting sleeve specimens was obtained by drawing test.The influence of anchorage bar diameter and anchorage length on the anchorage capacity of grouting sleeve was studied.The test results show that the larger the diameter of the anchorage steel bar,the longer the anchorage length of the steel bar,and the stronger the anchorage capacity of the grouting sleeve specimen.(2)The nonlinear finite element model of assembled double-column pier is established,and its seismic performance is analyzed from two aspects of hysteretic performance and damage mechanism.The accuracy of the numerical simulation method used in this paper is verified by comparing with the existing test,and compared with the cast-in-place double-column pier,the difference of seismic performance between the two is analyzed.The results show that :(1)The results of experiment and numerical simulation are basically consistent,and the maximum error is 5.2 %,which indicates that the method used in this paper is reliable and credible.(2)Compared with the cast-in-place double-column pier,the yield load,peak load and yield displacement of the assembled double-column pier are larger,the energy dissipation capacity is stronger,but the residual displacement is larger,and the peak displacement and ductility coefficient are smaller.(3)The damage area of the assembled double-column pier is smaller,the damage degree is lighter,and the seismic performance is better.(3)The finite element model of assembled double-column pier with different connection parameters is established,and the influence of key connection parameters(length of grouting sleeve,diameter of longitudinal reinforcement and position of grouting sleeve)on the hysteretic behavior and damage mechanism of assembled double-column pier is analyzed.The results show that :(1)The length of grouting sleeve is positively correlated with the yield load,peak load and energy dissipation capacity of assembled piers,and negatively correlated with yield displacement and ductility coefficient.The longer the length of the grouting sleeve,the higher the plastic zone position of the lower part of the assembled double-column pier,the smaller the area of the plastic zone,the lighter the damage at the top and lower parts of the pier,and the pier stress distribution is more uniform;(2)The diameter of longitudinal reinforcement is positively correlated with the yield load,peak load,yield displacement,energy dissipation capacity and residual displacement before reaching the ultimate load,and negatively correlated with the ductility coefficient and residual displacement after reaching the ultimate load.The larger the diameter of the longitudinal steel bar,the lighter the damage at the top and bottom of the assembled pier,and the more uniform the stress distribution of the pier;(3)Compared with the grouting sleeve located at the top of the cap,when the grouting sleeve is located at the bottom of the pier,the yield load,peak load and yield displacement of the assembled pier are larger,the energy dissipation capacity is stronger and the residual displacement is smaller,but the ductility coefficient is smaller.When the grouting sleeve is located at the bottom of the pier,the damage at the top and bottom of the pier is lighter and the stress distribution is more uniform.(4)The models of prefabricated bridge piers with different pier column layouts are established,and the differences of hysteretic performance and damage mechanism of prefabricated bridge piers with different pier column layouts are analyzed.The results show that when the bending moment of inertia is equal,the double-column pier has larger yield load and ultimate load,stronger energy dissipation capacity and smaller residual displacement than the single-column pier and the three-column pier.Compared with single-column pier and threecolumn pier,the plastic area of double-column pier is larger,the damage of vulnerable area is lighter,and its seismic performance is better.