Experimental Study On Flexural Behavior Of Fiber-polymer Modified Cement-based Composite Beams

Reinforced concrete structure has different degree of aging and damage due to its own material and using environment.In order to restore its function,the existing structure is usually repaired and strengthened.At present,China has a large number of infrastructure needs to be strengthened and repaired every year and in the next five to ten years will enter the peak period of repair.Therefore,it is necessary to develop a new strengthening materials to improve the strengthening effect.Fiber polymer modified cement is based on polymer modified cement and fiber reinforced cement.Compared with the traditional cement-based materials,it has the advantages of high compressive strength,good bonding property of transition interface and good deformation performance.The material itself has many advantages,but we do not know how to apply such a new material to the building structure.In this paper,the working mechanism of steel bar and concrete is analyzed,also the development process of normal section force,crack of reinforced concrete beams and the influence of concrete deformation performance on crack expansion.The fiber polymer modified cement of composite beam was formed by replacing the C50 concrete with 100-200 mm thickness at the bottom or 50-200 mm at the top.Study on the relationship between load and deflection of composite beam and ordinary beam during loading,stress change law of longitudinal tensile steel bar,Whether the strain along the beam height conforms to the assumption of plane section during bending of composite beam,distribution and development of cracks during loading.The conclusion is as follows:1.Compared with ordinary concrete,the yield load and ultimate load of composite beams in compression zone replaced by fiber polymer modified cement based materials decreased,increase the deflection of the beam.The addition of new material in composite beam has no influence on the crack,there's almost no difference.2.Compared with ordinary concrete,fiber polymer modified cement based material can improve the yield load and limit load of the composite beam,increase the deflection of the beam.The crack distribution of the composite beam has the characteristics of dense and fine.