Study On Stiffness And Mechanical Properties Of The Reinforced Concrete Beam Which Is Strengthened By The High Performance Ferrocement Laminate After The Fire

High performance ferrocement laminate(HPFL)using steel as reinforced material and high performance cement mortar as the base material of thin layer structure.Compared with traditional repair methods of reinforced concrete structure,HPFL has strong compatibility with concrete structure,and is of good ductility,good fire resistance performance to high temperature,does not affect the original structure space height,environmentally safe,etc.Study on bending capacities of RC slabs and bending stiffness of RC beam slab assemblies which are strengthened by HPFL after high temperature.The main contents and conclusions are as follows:(1)Summarizes the researches of the domestic and foreign scholars about mechanical properties and thermal performance of the steel and concrete after high temperature.At the basic of which came up with simplified calculation models about strength and elastic modulus of steel and concrete after high temperature on this basis.(2)Introduce the developing process of fire and the equal method between standard fire curve and actual fire curve.Then use the analytical method,finite difference method and finite element difference mixing method to deduce the temperature field of RC beams under high temperature.Finally,Use finite element analysis software ANSYS to simulate the temperature field of RC beams in different working condition under high temperature.(3)Use the effective moment of inertia method and analytical stiffness method respectively to deduce the stiffness and deflection computational formula of the RC beams strengthened by HPFL after fire.Then use bond-slip theory to deduce the crack computational formula of the RC beams strengthened by HPFL after fire.Finally,the rationality of computational formulas are certified by the experimental data which is given by YeQin in HuNan university.(4)Summarizes the research findings about the relationship between static stiffness and dynamic stiffness,and uses the theory of structural dynamics to deduce the natural frequency computational formula of the RC beams strengthened by HPFL after fire.The rationality of computational formula is certified.(5)Use finite element analysis software ANSYS to simulate the natural frequency and bearing capacity of the RC beams strengthened by HPFL after fire.The natural frequency computational formula which is given in this paper is certified by the simulated result.(6)An engineering project about the reinforced concrete beam which is strengthened by the high performance ferrocement laminate after the fire is given to prove the validity and practicability.