Experimental and numerical investigations of rigid IPE beam connections with drilled flange and web stiffener

After the occurrence of the 1994 Northridge earthquake, a new type of connection called the Reduced Beam Section (RBS) was introduced in steel moment resisting frames. The main purpose of this connection is to weaken the beam at a finite distance from the location of the connection so that smaller forces and moments are transferred to the connection. In addition to major advantages, RBS connections also have some disadvantages amongst which local buckling of the beam's web, strength decrease in the beam in the face of lateral-torsional buckling, and stress concentration increase in the cut area of the beam's flange can be mentioned. All of these, especially in slender sections such as the IPE profile, cause a precipitous drop in the moment-rotation diagram of the connection. The purpose of this study is to utilize horizontal-vertical and diagonal stiffeners to improve the performance of IPE beams with drilled flanges. Through three experimental tests and 15 verified numerical models, it was revealed that using diagonal and horizontal-vertical stiffeners in the web of the beam and in the reduced area, without a significant strength increase, expands the area under the hysteresis diagram and the plastic rotation capacity of the connection.