Experimental study of rigid connection of drilled beam to CFT column with external stiffeners

Abstract

This research is intended to investigate the behaviour of rigid connection of steel beam to CFT column with external T stiffeners. However, the investigations have shown that the stress concentration in the location of stiffener groove welds to the beam flange and column web causes abrupt fragile failure leading to ductility reduction of the connection. In the current study, beam section is reduced using the method of drilling beam flange so as to diminish the stress concentration and increase the ductility. This method is much easier to fabricate compared to RBS (cutting with CNC machine) and more applicable for existing buildings as well. In this research project two series of analytical models with constant and variable holes are investigated to evaluate the effects of different parameters of drilling on the local behavior of connections. Finite element method using ABAQUS software has been employed for analyses. In another part of this survey, two full scale samples are selected out of the analytical models, and experimentally investigated. According to the obtained results, drilling the beam flange results in decrease in stress concentration in the connection location of stiffener to the beam and column. In addition, it decreases the probability of failure in the expected modes 1 (shear failure of T-shaped horizontal stiffener) and 2 (tension failure of T-shaped vertical stiffener in connection to the column web) and increase the ductility of connection. Moreover, such connections can be used in the intermediate as well as special moment resisting frames.