EFFECT OF FIBERS ON DEVELOPMENT SPLICE STRENGTH OF REINFORCING BARS IN TENSION/

The effects of fibers on development/splice strength of reinforcing ba rs in tension were experimentally investigated. Three series of tests, with five beams each, lap spliced at midspan, were carried out, The r esearch parameters were: bar diameter (d(b)) fiber type, fiber volume fraction (V-f), and fiber-reinforcing index (VfL/d(f)). The beams,were loaded in positive bending with constant moment along the splice regi on. The current experimental results demonstrated clearly that the use of hooked steel fibers in concrete matrixes increases significantly t he development/splice strength of reinforcing bars iii tension: Using hooked steel fiber up to 2 percent by volume increased the development /splice strength by up to 55 percent. Also, the presence of fibers inc reased the number of cracks formed around the spliced bars, delayed th e growth of the splitting cracks, and consequently, improved the ducti lity of bond failure. While the use of polypropylene fibers, added in 0.6 percent by volume, improved the bond performance in the post-split ting range, they were not as effective as steel fibers in increasing t he development/splice strength of the reinforcing bars.