Experimental And Numerical Simulation Research On Repairment And Reinforcement For Seismic Damage Reinforced Concrete Members

In China, it is clearly stipulated in the current code for seismic design of buildings(GB50011-2010) and its old versions that “no damage under minor earthquake, repairable damage under moderate earthquake, no collapse under major earthquake”. For the situation of the “repairable damage under moderate earthquake”, how to take the reasonable, effective and convenient technologies of restoration and reinforcement is the key issue to be solved in engineering. Reinforced concrete beam and column are important part of frame structure, which exists a high risk of damage even under a moderate level’s earthquake, and by the analysis of a large number of earthquake disasters, seismic damage of the component tends to be concentrated in its end, less research relates to reinforcement performance of the members with a “repairable damage”. In order to ensure the safety of the main structure, this paper mainly studies the and anti-seismic performance, mechanical properties and reinforcement measures of the ends of the reinforced concrete beams and columns after their damages and reinforcements, provides the experimental and theoretical references for revising the design code for strengthening concrete structure and the code for seismic design of buildings. In this paper, the main research work and innovative achievements include:1)Design and production of six specimens of reinforced concrete columns and six specimens of the ends of the reinforced concrete beams, among of which two columns and two ends of beams were one-time loaded to failure, test data was collected for comparison. The other specimens were reinforced after received damage. The first step is the low cyclic loading test for the original specimens; the second step is the low cyclic loading test for the damaged specimens which the carbon fiber reinforcement and steel reinforcement, In consideration of the influence of parameters of different axial compression ratio and reinforcement methods to columns, the different longitudinal reinforcement ratio and reinforcement methods to ends of beams. The anti-seismic performance of specimens is analyzed, which includes hysteresis curves, skeleton curves, energy dissipation, ductility, stiffness degradation etc. The test results show that the reinforced column specimens with a small axial compression ratio of specimens have high energy consumption than those with a large axial compression ratio, the damaged ends of beams that reinforced by carbon fiber reinforced polymer(CFRP) can effectively restrain the extension of plastic hinges and the broken off of concrete, and show a better anti-seismic performance such as good load-carrying capacity, energy-dissipating capacity and ductility etc.2)It is difficult to determinate numerical model parameters of damage specimens for simulation analysis. Introduction of the "degradation coefficient of section stiffness" into the "section equivalent stiffness" method and the "damage coefficient of concrete strength" into the "equivalent strength of section bearing capacity" method, which used to determine the key numerical model parameters of the specimens by simplified analysis. Numerical modeling and analysis have been carried out on the reinforced concrete specimens with different reinforced methods by using ANSYS finite element program. The comparative analysis shows that the numerical results are in good agreement with the experimental results, to further validate rationality and credibility of the numerical model and the key parameters that determined in this paper.3) The experimental results show that bearing capacity of columns and the ends of beams after reinforcement have improvement in different degree. The shearing capacity calculation model of reinforced concrete damage reinforcement columns and the ends of beams are established in this paper. The experimental data verify this calculating method, which provide the theoretical basis for the design of practical engineering reinforcement.