The use of headed bars often provides an adequate solution to steel congestion, particularly at beamcolumn joints. An experimental research was performed to evaluate the applicability of closely spaced headed bars in exterior beam-column joints. Two large scale cyclic beam-column joint tests were carried out to examine seismic anchorage behavior of headed bars. The variables selected for seismic tests were the small clear spacing and two layers of headed bars in the beam which are both prohibited by ACI 318- 11. The behavior of the tested connections showed satisfactory seismic performance for both specimens. It was concluded that the clear bar spacing of approximately 2.3db or the use of two bar layers may be permitted for headed bars anchored in exterior beam-column joints.

Keywords