Effect of Beam Depth on Anchorage Strength of Hooked and Headed Bars
Zachary Coleman, Eric Jacques, and Carin Roberts-Wollmann
Appears on pages(s):
anchorage; beam-column joints; bond and development; effective beam depth; headed bars; hooked bars; lever-arm distance; strut angle
Several studies have reported that the flexural lever-arm distance can influence the anchorage strength of hooked and headed bars. However, this so-called “beam-depth effect” is not reflected in design practice because it has not been sufficiently studied. The objective of this paper is to evaluate the influence of the lever-arm distance on anchorage strength. A database of 445 anchorage tests of hooked bars was assembled. Increases in the effective beam depth were found to correlate with decreases in the anchorage strength of hooked bars. Multivariable regression analyses were used to develop descriptive equations for the anchorage strength of hooked
bars considering various parameters, including the effective beam depth. A modification factor accounting for the beam-depth effect was proposed for the ACI 318-19 equation for the development length of hooked bars. Preliminary analyses suggested that a similar beam-depth effect may exist for headed bars.