Study On The Effect Of Impact Object Shape On Low-Velocity Impact Damage Of GFRP Reinforced Concrete Cylinders

Glass fiber composite reinforced material(GFRP)reinforcement is becoming a new construction material widely used in the civil engineering industry because of its high corrosion resistance and high tensile strength.However,considering the anisotropic and brittle characteristics of GFRP material,the mechanical behavior of GFRP reinforced concrete structure under impact is significantly different from that of reinforced concrete structure.Under impact,GFRP reinforcement is more likely to cause damage than steel reinforcement,which can lead to serious consequences of structural collapse.Therefore,it is important to study the dynamic response process of GFRP reinforced concrete members under the action of low-velocity impact and the residual load capacity of damaged columns to reduce the occurrence of safety accidents.A drop hammer impact test apparatus designed by the group was used to conduct low-velocity impact tests on GFRP reinforced concrete columns and axial compression tests on the impact-damaged specimens to quantify the effect of impact damage on their residual bearing capacity.In the low-velocity impact test,the mechanical behavior of GFRP reinforced concrete cylinders under the impact of a certain mass of falling hammer but with different hammer head shapes was investigated by analyzing the impact dynamic response process,the degree of damage,the impact force time course curve and the support force time course curve of the specimens.The test results show that the hammer head shape from fine prismatic hammer head,spherical hammer head,wide prismatic hammer head to flat hammer head,the contact area between the hammer head and the specimen is increasing,and the degree of damage caused by the impact on the specimen gradually increases;within a certain range,the contact area between the hammer head and the specimen is too small or too large will cause different degrees of damage to the specimen GFRP hoop;at the same time,with the oscillation of the time course curve of the impact force The corresponding peak impact force will increase significantly.In the axial compression test,the axial compression damage,load-displacement curve,load-strain curve and other performance characteristics of the specimens impacted by different hammers were systematically analyzed relative to the non-impact reference specimens to quantify the degree of impact effects on the residual load carrying capacity of GFRP reinforced concrete cylinders under different hammer head shapes.Meanwhile,the test results show that despite the impact damage,the GFRP spiral hoop reinforcement still has a significant restraining effect on the concrete in the core area of the enclosed beam under the axial load.