Anchorage of beam and column bars within joint cores
With cyclic loading in regions of high seismicity, large bond forces may develop in the joint core at an interior
joint leading to bond degradation and excessive slip of the bars, resulting in yield penetration into the joint
region. This is because in frames designed to dissipate energy via a beam sidesway mechanism, large steel
stresses need to be transferred by bond to interior joint cores over relatively short lengths of beam longitudinal
bars. In the limit, the bar may be stressed to yield in tension on one side of the joint core, and to yield in
compression on the other side. In order to reduce the amount of slippage, strict rules can be used to limit the ratio
of the bar diameter to the column depth, with some relaxation of this if a large compressive load acts on the
column [Park, 1992].