Experimental Study On Seismic Performance Of Corroded Reinforced Concrete Columns Confined By Large Strain FRP

Traditional FRP(Fiber Reinforced Polymer)composite materials have low fracture strain,so the application effect of the reinforced concrete structure in seismic reinforcement is not ideal.Large strain FRP(LRS-FRP),as a new type of fiber reinforced material with high fracture strain(greater than 8%),can overcome the problems of traditional FRP and effectively improve the ductility of the structure.Based on the above background,from the purpose of exploring the seismic performance of LRS-FRP,this paper mainly completed the following work:A test column with electrochemical corrosion treatment of only the longitudinal ribs of the plastic hinge region was designed and manufactured,and subjected to a low-cycle repeated loading test.Taking the corrosion rate,number of cladding layers,material type and axial compression ratio as research parameters,the influence of these parameters on the failure mode and seismic performance of the test specimens was studied.Observe the development of cracks and damage patterns of each specimen in the loading process,and compare and analyze the difference in the failure mechanism between corroded and uncorroded columns,and between the reinforced and unconsolidated columns;evaluate the seismic performance indicators of all test columns.Including hysteresis curve,skeleton curve,stiffness degradation,ductility coefficient,energy consumption,bearing capacity increase,curvature change,quantitative analysis of the seismic performance enhancement of corroded columns after LRS-FRP reinforcement.Through the above work,the following main conclusions have been drawn:(1)The corrosion of longitudinal reinforcement has a great influence on the seismic performance of the specimen.With the increase of the corrosion rate,the ultimate bearing capacity of the test specimen is significantly reduced,and the ultimate bearing capacity of the specimen after reinforcement is significantly improved.(2)When the axial pressure is relatively low,different reinforcement methods can significantly increase the ductility and energy consumption of the rusted column,but in the case of the same constrained stiffness(wrap layer number),the LRS-FRP shows betterDuctility and energy consumption increase capacity.(3)Under high axial-pressure ratio,the bearing capacity and ductility of the rusted specimens are greatly reduced.The reinforced columns partially improve the ductility and energy consumption of the specimens,while the full-envelope reinforcement columns still have excellent energy-consumption enhancements.Compared with the high axial compression ratio of the fully wrapped column,the energy consumption of the rusted specimen increases significantly.(4)Through the comparison of seismic performance indicators such as skeleton curves,it is found that the reinforcement has no significant effect on the stiffness of the specimen,but only delays its stiffness degradation rate.The innovations of this thesis can be summarized as follows:(1)In this paper,a reinforced concrete column considering the corrosion of vertical reinforcement only was designed and designed,and only the plastic hinge area was rusted.The influence of longitudinal reinforcement corrosion on the seismic behavior of long columns with failure mode of bending failure was studied.(2)The large-strain FRP is used for seismic reinforcement of corroded columns,giving full play to its advantages of large deformation capacity and good ductility,and effectively improving the seismic performance of corroded columns.