Effect of perpendicular beams on failure of beam-column knee joints with mechanical anchorages by 3D RBSM

When mechanical anchorages are placed near the surface of a beam-column knee joint, anchorage failure may occur because of local stresses from anchorage plates. Perpendicular beams placed on both sides of the joint can be a way to avoid the occurrence of this failure. In this study, a meso-scale discrete analysis using 3D RBSM is conducted to investigate the effect of perpendicular beams on the behavior of a beamcolumn knee joint with mechanical anchorages and their effect on failure mode. By studying the internalstresses and cracks in a beam-column knee joint with mechanical anchorages, perpendicular beams can improve its performance in terms of loading capacity and failure behavior. Perpendicular beams are known to have two effects. The perpendicular beams increase bond performance along the development length of anchorages and resist the opening of the diagonal cracks. It has the same failure mode as in the case without perpendicular beams which is an anchorage failure, but the occurrence of the anchorage failure is delayed in this case. It is also inferred by simulation that the effective length of the perpendicular beams is determined by approximately 45 degrees inclination to the longitudinal beam, measured from the original position of anchorage plates.