Research On Fatigue Performance Of Concrete-TRM Bond Behavior

The method of using Textile Reinforced Mortar(TRM)to reinforce concrete structures involves embedding high-strength fiber textile mesh into polymer cement mortar and bonding it to the surface of the tensioned concrete.However,the reinforced structure is often subjected to variable loads,which increases the risk of fatigue failure for TRM reinforcement method.The application of pre-stressing on the fiber fabric further exacerbates the risk of failure.Currently,research on the fatigue mechanism of the interface of TRM-reinforced concrete structures is not mature enough,and research on pre-stressed TRM-reinforced concrete structures is still in its infancy.Therefore,this study conducted a mechanical analysis of TRM-reinforced concrete structures under static and fatigue loads based on interface and beam tests.The following conclusions were drawn:(1)A TRM-concrete interface force model was proposed and analyzed based on existing fiber-reinforced concrete structure tests,revealing the failure process and stress transfer mechanism of the TRM-concrete interface under static loading and the role of friction in force transmission at the interface.The calculation method of the interface bonding-slip curve was given through an analysis of static test data on the TRMconcrete interface.The fracture energy of the interface was obtained using fracture mechanics,and the interface peeling load was verified through experimental data to demonstrate the feasibility and accuracy of this method.(2)The study of the fatigue failure mechanism of the TRM-concrete interface revealed that when the interface was subjected to high load amplitude and low loading frequency,the slip,energy dissipation,and stiffness of the TRM-concrete interface exhibited greater damage compared to low load amplitude and high loading frequency.(3)A formula for the fatigue crack growth rate of the TRM-concrete interface was proposed based on the Paris formula and fracture mechanics.The formula was compared with experimental results to demonstrate its reasonableness.(4)The fatigue test results of pre-stressed TRM-reinforced concrete beams showed that the concrete strain,steel strain,and beam deflection all exhibited a three-stage development rule of "fast early stage,stable middle stage,and rapid late stage." When the fiber fabric was under high pre-stress levels,greater damage was observed in the test beam and the TRM-concrete interface.(5)A nonlinear numerical analysis method that comprehensively considers the bonding and material damage of the TRM-concrete interface was proposed and validated through simulating TRM-concrete interface and beam failure tests,further complementing the research results.