A Study of Hooked Bar Anchorages in Beam-Column Joints
Jose L. G. Marques and James O. Jirsa
Appears on pages(s):
anchorage (structural);beam-column frames;beams (supports);hooked reinforcement; joints (junctions);freinforced concrete;structural engineering.
Twenty-two specimens simulating typical exterior beam-column joints in a structure were tested to evaluate the capacity of anchored beam reinforcement subjected to varying degrees of confinement at the joint. The effects of column axial load, vertical column reinforcement, side concrete cover, and lateral reinforcement through the joint on the performance of standard hooked bars were studied. The tests were conducted using either #7 or #11 beam bars anchored in the columns. Standard 90 or 180 deg hooks comforming to ACI 318-71 specifications were used throughout. Based on oberservations of the test specimens, current ACI 318-71 Code specifications are studied and design recomendations for hooked bar anchorages proposed. Comparisions of the design recommendations with the measured results indicate that higher stresses could be allowed for hooked anchorages provided that confinement in the form of cover or ties and straight lead embedment before the hook were sufficant.