Study On Impact Resistance Of Short Cut Carbon Fiber Reinforced Concrete

In actual construction,buildings will inevitably be affected by impact load.In order to improve the impact resistance of concrete materials,this paper adds chopped carbon fiber into concrete instead of some fine aggregate,and uses the impact resistance of fiber reinforced concrete to carry out the experimental study on the impact resistance of carbon fiber reinforced concrete.In order to ensure the feasibility of the test,the short cut carbon fiber with a length of 60mm is used to replace the corresponding fine aggregate according to the volume ratio(0%,0.1%,0.2%,0.3%)to improve the impact resistance of concrete materials.This paper mainly includes two parts:testing and analyzing the drop hammer impact resistance of short cut carbon fiber reinforced concrete,and testing and analyzing the damage of short cut carbon fiber reinforced concrete after impact.(1)With the increase of chopped carbon fiber content,the number of times the specimen can withstand the drop hammer impact increases.The average impact times of specimen cf0 when cracks appear for the first time is 3.6 times,and the average impact times required for final failure is 5 times.The average impact times of specimen when cracks appear for the first time are 16 times,and the final impact resistance times are 19.3 times.The impact resistance of 3.4 times higher than that of cf0.After the initial crack,the ability of the specimen to continue to bear the impact load will increase with the increase of the content of chopped carbon fiber.can continue to withstand 1.4 times of impact after initial crack,while can continue to withstand 3.3 times.The impact resistance of Test piece with carbon fiber content of 0.3%after initial crack is 1.35 times higher than that of Test piece with carbon fiber content of 0%.(2)With the increase of drop hammer impact times,the overall ultrasonic wave velocity of all short cut carbon fiber content specimens decreased,the wave velocity of specimen cf0 decreased by about 3.5%,the wave velocity of specimen Test piece with carbon fiber content of 0.1%decreased by about 3.1%,the wave velocity of specimen Test piece with carbon fiber content of 0.2%decreased by about 2.6%,and the wave velocity of specimen Test piece with carbon fiber content of 0.3%decreased by about 1.8%.Accordingly,the damage factors obtained by calculation are increased.With the increase of chopped carbon fiber content,the increase degree of damage factor will decrease after impact.When the impact times are constant,the greater the content of chopped carbon fiber,the smaller the damage factor in the whole range.(3)When the falling height of the steel ball is constant,the rebound height of the steel ball will decrease with the increase of the content of chopped carbon fiber.When the falling height of the drop hammer is 115mm,the energy absorbed by specimen Test piece with carbon fiber content of 0.3%is 11.4%more than that of specimen Test piece with carbon fiber content of 0%.The energy absorption capacity of the specimen increases with the increase of the content of chopped carbon fiber.(4)In this paper,the drop hammer impact system is numerically simulated by using the discrete element software PFC2D,and the parameters of the simulated specimen are calibrated with the basic data of short cut carbon fiber reinforced concrete.The simulated and real data are compared,and the influence of chopped carbon fiber content on the impact resistance of concrete specimens is comprehensively analyzed.Through numerical simulation,it is found that under the same impact times,the extension degree of internal crack increases with the increase of chopped carbon fiber content.In the case of impact for 3 times,the number of internal cracks in Test piece with carbon fiber content of 0.3%is about 3 times more than that in Test piece with carbon fiber content of 0%.Figure:40 Table:7 Reference:65...