NUMERICAL STUDY ON THE SEISMIC BEHAVIOUR OF A NEW REDUCED BEAM SECTION CONNECTION BY DRILLED HOLES ON THE BEAM FLANGE

One of the major destructions of steel structures occurred in the 1994 Northridge earthquake and the 1995 Kobe earthquake as a result of the friable behavior of beam-to-column joints in the flexural frame system. In this regard, one of the ways to improve the joints in flexural frames is to weaken an area of the beam in order to prevent the brittle fracture of the joints. Therefore, in this study, we have investigated a special type of flexural frame joints that try to meet specific seismic conditions. This moment resisting connection with a reduced cross-section of the beam flange as a drill hole (Drill Flange Connection – DFC) results in the transmission of the plastic joint into the beam and is compared to the preapproved Reduced Beam Section (RBS) connection using the ABAQUS software. Also in this research, the effect of hole arrangements, hole diameters, number of rows of holes and distances a, b, c (RBS area) is assessed to obtain a suitable pattern for utilizing this type of connection. The results show that the arrangement of the holes with three rows of unequal diameter and respectively from a small to a large diameter has the best distribution of plastic strain within the beam. Also, the most suitable diameter is in the f f 0.1b  D  0.23b range. The most suitable distance from the (a) column face is in the f f 0.5b  a  0.75b range and the best reduced area distance (b) is in the b  0.75d range. The most appropriate distance from the center of the hole to the wing edge (c) is in the f f 0.1b  c  0.25b range. This provides the best template for the special flexural frame system.

Keywords:

DFC Connection , Reduced Beam Section , Ductility , Moment resisting