Development length of FRP straight rebars

In recent years, some attempts have been performed to extend general design rules reported in the codes for steel reinforced concrete to Fiber Reinforced Polymer (FRP) materials; this is the case of relationships adopted in the evaluation of the development length clearly derived by extension of the formulations used for steel rebars. However, such relationships seem to be inappropriate for FRP reinforcing bars: in fact, experimental test results have shown that bond behaviour of FRP bars is different from that observed in case of deformed steel ones. As a consequence, a new procedure for the evaluation of development length based on an analytical approach is needed in order to directly account for the actual bond-slip constitutive law as obtained by experimental tests on different types of FRP reinforcing bars. An analytical solution of the problem of a FRP rebar embedded in a concrete block and pulled-out by means of a tensile force applied on the free end is presented herein. Such solution leads to an exact evaluation of the development length when splitting failure is prevented. Finally, based on the analytical approach, a limit state design procedure is suggested to evaluate the development length. (C) 2002 Elsevier Science Ltd. All rights reserved.