Investigation On Temperature Effect And Vehicle Impact Response Of CFRP Cables

Carbon-Fiber-Reinfoced-Plastics/Polymers(CFRP)cable can essentially overcome the durability of traditional steel cables caused by corrosion and fatigue,because of its high strength,light weight,superior corrosion resistance and fatigue resistant.At present,scholars have made a detailed demonstration of CFRP cables' rationality in the structural static and dynamic behavior,as well as the economical practicability.However,due to the disadvantages of CFRP,the CFRP cables will encounter two problems: the first,the transverse shear strength of CFRP cables is much lower than its axial tensile strength;the second,CFRP cables has poor high temperature resistance.With the fast development of China's economy,the number of car ownership has grown rapidly,and traffic accident frequency has become a serious social problem.In the operation process of the bridge,in addition to the impact of the vehicle,the CFRP cables may also be affected by fire caused by car accidents.Therefore,the impact resistance of CFRP cables and its high temperature resistance have become the key issues that restrict its application.At present,the research on the static performance of CFRP cables after high temperature is not enough,and there are few reports on CFRP cables response under the vehicle impact.Therefore,to solve the two key problems of the CFRP cables,this paper conducted investigations on the the static performance of CFRP ribs after high temperature and CFRP cables response during the vehicle impacting process under the financial support of the National Key Research and Development Plan “Key Technology Integration and Demonstration of New Structure Application of Fiber Reinforced Composites ”(No.2017YFC0703008),and the National Natural Science Foundation of China,“Research on the impact performance of CFRP cables and anchor system”(No.51478177).The research mainly includes following studies and draws conclusions as follows:Axial tensile tests static load tests were conducted on 9 specimens with different elevated temperatures.The results show that: two failure modes,fracture and sliding failure of the CFRP bars,were found in those specimens.The axial tensile property of the CFRP bar and the bond anchorage property between CFRP bar and RPC(Reactive Powder Concrete)slightly degenerate when the elevated temperature was lower than 100?.The corresponding average bond strength between the bar and RPC and elastic modulus of the CFRP bar reduced by 34.5% and 9.1% when the elevated temperature was 200?,respectively,compared to the specimens exposed to 30?.The equations for predicting the axial tensile properties of CFRP bar were established based on the test results.Transverse static load tests were conducted on 15 specimens with different elevated temperatures and pretension ratios.The results show that: the failure mode of all specimens was fracture of the CFRP bars.As temperature increased from 30 to 200?,the ultimate cable tension,maximum cable tension increment and transverse breaking force of the CFRP bar decreased while the ultimate transversal deformation was almost unchanged.As the pretension ratio increased from 0 to 0.34,the maximum cable tension increment,transverse breaking force and ultimate transversal deformation of the CFRP bar decreased while the ultimate cable tension increased.Additionally,the equations with enough accuracy for predicting the ultimate transverse deformation,ultimate cable force and transverse breaking force of CFRP bars subjected to different elevated temperatures were proposed.Low-velocity impact tests were conducted on 12 specimens with different pretension ratios.The results show that: the failure mode of all specimens was fracture of CFRP bars,and the fracture section was flatter than that of the transverse static test specimen.As the pretension ratio increased from 0 to 0.34,the maximum cable tension increment,transverse breaking force and ultimate transversal deformation of the CFRP bar decreased while the ultimate cable tension increased.Because of the shear effect and contact damage,the maximum cable tension,maximum contact force and tanverse deflection in the impact test were 89%,72% and 82%,repectively,of those in transverse static tests.The CFRP cables response under the impact of F800 truck at different speeds and when the spring stiffness changed were analyzed with LS-DYNA finite element.The results show that as the truck speed increases from 20 km/h to 1 20 km/h,the peak cable force and peak impact force of the CFRP cable increased,and the impact contact time decreased.As the spring stiffness increased,the peak cable force and peak impact force of the CFRP cables increased,while impact contact time and the vertical deformation of the cables decreased.