Study On Dynamic Response And Failure Effect Of Pc Beams Under Impact Loading

In prefabricated concrete structures,a large number of specimens subjected to major loads like precast composite beams are often exposed to a great threat of impact accidents,and it is of significant importance to research the impact resistance of precast composite beams in the field of disaster prevention and reduction of civil engineering.In this paper,the dynamic behavior characteristics and damage effects of PC composite beams and RC beams under impact load are studied by means of experiments and finite element simulation.The main research work is as follows:(1)The dynamic tensile properties of grouting sleeve were studied.The stress-strain curves were obtained through 48 unidirectional tensile tests under different loading rates.The failure modes and failure mechanisms were researched and the parameters affecting the dynamic tensile properties of grouting sleeves were further analyzed.The effects of loading rate,anchorage length of reinforcing bars and grouting sleeve type on the tensile properties were discussed.(2)Drop hammer impact tests were conducted to analyze the effects of hammer head weight,impact velocity and impact energy on the impact resistance of four PC composite beams and four RC beams.During the test,signal of impact force and strain of concrete and reinforced bars were discussed.The typical failure modes of beams were obtained.The failure process of PC composite beams and RC beams were described clearly.Static loading tests of one PC composite beam and one RC beam were carried out,and the static and dynamic tests were compared.(3)The prediction formulas of peak deflection and residual deflection were fitted.According to the formulas,the peak deflection and residual deflection of PC composite beams and RC beams can be quickly obtained through impact velocity and impact mass.The residual deflection ? was used as damage control index,and the M-V curve for evaluation of PC composite beams was measured.The curve was used for rapid evaluation of beams under serviceability limit state to provide a basis for the impact resistance design of prefabricated composite beams.(4)The finite element models of 8 concrete beams under impact load were developed for the impact simulation of PC composite beams and RC beams.The mid-span displacement,hammer impact force and failure pattern nephogram were compared with the test results to validate the accuracy of the model,the PC composite beam was parameterized by changing the hammer mass and impact velocity.