Tensile lap splicing of bundled CFRP reinforcing bars in concrete

In the case of heavily reinforced concrete structural members, bundled bars are required rather than spaced bars. The use of spliced bundled bars is necessary when available bar lengths are limited. No design recommendations regarding the use of bundled or spliced bundled FRP bars are available. The results of four-point flexural testing of nine concrete beams reinforced with spliced bundled CFRP bars are presented herein. The effects of the type of bundle and splice length on the bond strength of bundled CFRP bars are investigated. Based on the experimental results, a procedure for determining the critical splice length of FRP bars is presented and the corresponding values of bond stresses can be predicted. Moreover, the ultimate strength analysis method is used to predict the maximum stress in spliced bundled CFRP bars. Finally, comparisons with the existing recommendations regarding the use of bundled steel bars and the recommended modifications for bundled CFRP bars are presented.