Effect of transverse reinforcement on bond strength of reinforcing bars in silica fume concrete

The objectives of the research program were to investigate the effect of transverse reinforcement on the bond-slip characteristics of tension lap splices in high performance silica fume concrete, to study the validity of the upper limit of 70 MPa imposed by the ACI Building Code 318-95 on the concrete compressive strength for determination of development length, and to evaluate the reliability of the empirical equation of Orangun, Jirsa, and Breen in estimating the bond strength of tension lap splices embedded in high strength concrete and confined with transverse reinforcement. Twelve beam specimens were tested. Each beam specimen included two bars in tension, spliced at the center of the span. The beams were designed in way that bars would fail in bond, splitting the concrete conver in the splice region, before reaching the yield splice in a constant moment region. The variables used were the percentage replacement by weight of cement by silica fume and the amount of confinement over the splice region.