The Study On Seismic Performance Of Undrained Reinforcement Technology For Rapid Assembling Of Precast Concrete Segments

After long-term service,the substructure of bridge tends to have disease and damage problems,which will affect the seismic performance of the entire structure.Therefore,the substructure of these bridges needs to be reinforced.Aiming at some shortcomings of the current reinforcement method of bridge piers,this paper proposes a rapid assembly and undrained reinforcement technology of concrete segments,carry out the corresponding reinforcement design and conduct seismic performance research.The specific research content and achievements are as follows:(1)Concrete sections and nine components were designed and fabricated and quasi-static test studies were conducted.The specimen considers whether the filler concrete is added with expansion agent,column damage,tube reinforcement and slenderness ratio,and studies the seismic performance of the rapid assembly and undrained reinforcement technology of concrete segments.The results show that the connection method of the designed segments meets the strength requirements;the bearing capacity,stiffness and energy dissipation capacity of the reinforced test pieces are greatly improved;the addition of the expansion agent to the filled concrete will have a positive impact on the seismic performance of the reinforced test pieces;The weakening of the reinforcement reduces the stiffness and load bearing capacity of the test piece.(2)In order to study the influence of rapid assembly and undrained reinforcement technology of concrete segments on the seismic performance of test specimens,consider the thickness of concrete segments,the strength of the concrete of the filled layer,the strength of the filled concrete,the self-stress value of the filled concrete and the axial compression ratio.With the parameters,20 models were established using ABAQUS finite element software.The main results are as follows:the thickness of concrete segments and the strength of filled concrete are the key factors affecting the seismic performance of the reinforced columns.With the increase of the thickness of concrete segments,the bearing capacity and stiffness are improved,and the energy consumption is also significantly increased,but force decreases and the ductility deteriorates obviously.Increasing the strength of the filled concrete is the most effective method to improve the bearing capacity.However,the strength of the filled concrete will decrease the ductility;the strength of the concrete of the filled layer will have a relatively small impact on the seismic performance;The increase of self-stress value of layer concrete will have a positive impact on seismic performance.Finally,according to the influence trend of these parameters on seismic performance,corresponding design suggestions are proposed.(3)On the basis of experiments and finite element simulation,the restoring force model of rapid assembly and undrained reinforcement of concrete segments was established.Firstly,the calculation formulas of displacement,load and stiffness corresponding to the feature points of the three-fold line skeleton(yield point,peak point,limit point)are determined,and the skeleton model is established.Secondly,the unloading stiffness and hysteresis rule of each level are determined,and hysteresis is obtained.Finally,verify the validity of the restoring force model.(4)In order to verify the feasibility of the practical application of the rapid assembly and undrained reinforcement technology of concrete segments,this paper also carried out pilot engineering research,combined with the previous experimental research to summarize the rapid assembly and undrained reinforcement technology of concrete segments,and divided the construction process into several in 7 stages,quality control is carried out from 4 aspects to provide guidance and reference for subsequent reinforcement construction.