TENSION DEVELOPMENT LENGTH OF REINFORCING BARS EMBEDDED IN HIGH-STRENGTH CONCRETE

Research results presented earlier (phase I) concluded that in the case of high-strength concrete (HSC), increasing the tension development length (or equivalently tension splices) is not an efficient way of increasing the bond capacity of deformed reinforcing bars, especially when the cover concrete is small. Further, the previous report concluded that in the case of HSC, removal of the current ACI 318-89 (revision 1992) limitation on root f(c)' in calculating tension development length and tension splices should be coupled with some minimim stirrup requirement over the splice region, This paper presents the results of phase II of the study, an investigation to establish the minimum amount of stirrups. It also includes a tentative modification to the ACI 318-89 (revision 1992) requirement for calculating tension development length and tension splices when concrete compressive strength exceeds 10 000 psi (69 MPa).