Anchorage Characteristics of Non-metallic Reinforcement for Concrete

This article analyzes the basic problems of the anchorage of non-metallic reinforcement for concrete and reviews calculation methods of anchorage length using ACI, STR, JSCE and fib Model Code 2010. The paper presents a comparison of experimental (Benmokrane et al. 2003) and theoretical results and studies the major types of experimental tests to determine the bond strength of FRP reinforcing bars. The anchorage length of continuous fiber reinforcement (non-metallic reinforcement bars) is calculated using diff erent expressions proposed in codes and recommendations, thus providing with particular results. The article also shows how the anchorage length of a reinforcing bar is influenced by mechanical properties of reinforcement and concrete, concrete cover and the diameter of the reinforcing bar. Experimental results are compared with theoretically obtained values referring to codes and recommendations. A scatter of results is 3.67-10.18. It was found, that the anchorage length of the carbon fiber reinforced polymer (CFRP) bar calculated by ACI, STR, JSCE and MC increases in the number of times an increase in bar diameter. It has been stated, that anchorage length decreases by 1,44 and 1,71 when the compression strength of concrete increases by 2 and 4. Theoretical calculations have revealed that depending on a bar diameter, in order to minimize the anchorage length of non – metallic reinforcement, the use of the concrete cover higher than 3 db is not feasible. Moreover, when using conventional steel for concrete reinforcement, anchorage length is 3 times less than that of a concrete member with carbon fiber reinforced polymer (CFRP) reinforcement and 2 times less than using basalt fiber reinforced polymer (BFRP) reinforcement. Calculation methodology for the anchorage length of a steel reinforcing bar can be used for calculating the anchorage length of non-metallic reinforcement. However, individual coefficients of diff erent FRP reinforcement must be applied to determine environmental factors and temperature of mechanical properties of non-metallic reinforcement. The values of coefficients must be determined conducting experimental tests.