Study On The Performance Of Partially Prestressed Fiber Reinforced Concrete Beams

Road transport is one of the most common modes of transport,with the development of economy,the amount of traffic in our country is increasing and so does the car loading.Because most bridges are in the crack state in the actual engineering,the rate of crack propagation accelerates under heavy load traffic,which seriously reduces the bridge bearing capacity,and even leads to the collapse,affecting the service performance of the bridge.In the process of using the bridge,how to reduce cracks of bridge engineering has become an important issue to consider,for this problem,scholars have proposed adding fiber,the brittle performance of concrete,improve the crack resistance of concrete.Due to the lack of research on the properties of fiber reinforced partially prestressed concrete beams at home and abroad,the current codes also lack the calculation methods and design requirements for the bearing capacity of fiber reinforced prestressed concrete beams.Therefore,based on the actual engineering,12 test beams are designed by a scale model.The flexural and fatigue properties of carbon fiber,agamid fiber and hybrid fiber added to partially prestressed concrete are studied,which provides a theoretical basis for the practical application of the project.The main research contents are as follows:1.The axial compressive strength test of the fiber concrete block is carried out,and the comprehensive analysis of the comparative test results shows that the axial compressive strength of the fiber concrete with fiber volume ratio of 1% is the best;2.The flexural load,yield load and ultimate load are obtained by bending test of 4 beams,and the failure modes,deflection,concrete strain,strain and toughness of the test beam under static condition are analyzed.The test results show that the addition of fiber improves the cracking load,ultimate load and cracking resistance of concrete beams,and the optimum performance of hybrid fiber reinforced concrete beams are obtained by comprehensive comparison;3.Eight test beams were subjected to the same amplitude fatigue test.The fatigue life,material strain,midspan deflection and crack variation of the test beam under fatigue loading are analyzed.The test results show that the fatigue life of fiber reinforced concrete beams are higher than that of ordinary beams,both of which exceed 2 million times.Fiber doping can effectively reduce the cumulative internal damage of concrete,and the fatigue life is better;4.Based on the fatigue damage theory and fatigue crack propagation theory,the attenuation curve of the elastic modulus is analyzed,and the formulas for calculating the cracking moment and fatigue crack width of partially prestressed fiber reinforced concrete beams are proposed.