cyclic behavior of variously drilled flange beam connected to box column

The moment frame system is used as a lateral load resisting system against seismic loads. so far, a large body of research has been conducted on steel connections and various types of connections including reduced beam section (rbs) and drilled flange connection (dfc). using rbs results in the formation of inelastic deformation in a part of the beam far from the column flange. they have studied the seismic performance of the recently developed dfc as a simple and efficient alternative to mostly used conventional rbs. in this research, the beam flange is drilled in different patterns in terms of the hole diameter. after simulating the models in abaqus, the moment-rotation curves are extracted and analyzed numerically. having obtained the results of the current research regarding the moment connection where beam flanges are drilled, it is evident that drilling holes in the beam flange with a clock pattern can better satisfy the flexibility expectations. moreover, this pattern has the higher capability for plastic hinge transfer from the column face compared to the direct pattern. additionally, this pattern can reduce the bending stress in the penetration weld of the direct beam to column connection. thus, the clock pattern of beam flange holes performs better than the straight one.