Conventional and High-Strength Steel Hooked Bars: Detailing Effects

Findings from a study on the effect of hook bend angle, concrete clear cover, and orientation of confining reinforcement on hook anchorage strength are presented. The range of test parameters was much broader than in previous studies. Bar stress at anchorage failure ranged from 33,000 to 137,400 psi (228 to 947 MPa) and concrete compressive strengths ranged from 4300 to 16,500 psi (30 to 114 MPa). Anchorage strength of hooked bars was insensitive to bend angle (90 or 180 degrees) and side cover (between 2.5 and 3.5 in. [65 and 90 mm]). Confining reinforcement was found to increase anchorage strength for 180-degree hooked bars regardless of orientation (parallel or perpendicular to the embedment length). For 90-degree hooked bars, reinforcement oriented parallel to the embedment length had a greater effect on anchorage strength than reinforcement oriented perpendicular to the embedment length.