BOND STUDIES OF HOOKED BARS CONFINED WITH STEEL FIBERS IN NORMAL STRENGTH CONCRETE

摘要

The objective of the research study was to assess the effect of steel fibers dispersed in the concrete mix in improving the bond performance of hooked bars and ductility of the failure mode of beam-column connections. Twelve beam-column specimens with an intended nominal concrete strength of 28 MPa were tested. The specimen simulated the rigid connection of a cantilever beam to a column. It consisted of a vertical beam element anchored in a base column. The tensile beam reinforcement consisted of two bars anchored in the base column outside the column reinforcement cage using hooked-bar anchorages designed to ensure bond-splitting failure before the steel yielded. The variables were the beam bar size (16,25, or 32 mm) and the volume fraction of steel fibers placed and dispersed in the concrete mix (0, 0.5, 1.0, or 1.5%). Analysis of the test results revealed that steel fibers were effective in increasing the anchorage capacity and the ductility of the load-deflection history of specimens with steel fibers as compared with companion specimens identical in geometry and bar size but without steel fibers.