Experimental Research on T-Shaped Beam-Column Joints at Top Floor with Mechanically Anchored Reinforcement

Mechanical anchorage becomes popular for recent reinforced concrete construction because of the ease-to-install at congested connections. Column longitudinal reinforcement is anchored at T-shaped beam-column joints at top floor where the anchorage may be positioned beyond the beam core because columns typically have larger dimensions than beams. Thus premature failure can be caused at the anchorage; however, no design details have been provided in previous studies. Therefore, this study proposes a theoretical method to evaluate the minimal requirement for reinforcement to prevent anchorage failure of column longitudinal rebar. Static cyclic loading tests were conducted on three 1/2 scale T-shaped partial frame specimens representing a beam-column joint at top floor to examine the effectiveness of the proposed quantity of anchorage-reinforcing bars. The anchorage-reinforcing bars were intensively arranged at the ends of the anchor plates in all the specimens, while different amounts of joint shear reinforcement were applied to the specimens. Consequently, all the specimens failed with beam flexural yielding, and none obvious strength deterioration was observed until a drift ratio of 1/25rad. The theoretical requirement for anchorage-reinforcing bars proposed in this study is effective to prevent premature anchorage failure in T-shaped beam-column joints.