A steel frame connection: I-beam to SHS column via bolted T-stub

Abstract

This paper presents the outcome of an experimental study carried out by the authors on the performance of a connection between an I-beam and a square hollow section (SHS) column. In the light of practical and economic bolted field applications and transportation without damage by leaving the column exterior without projections, an appropriate joint type composed of T-stub connecting elements was studied. These connecting elements were bolted with long partially threaded studs passing through the SHS column. In order to observe the performance of the joint, four full-scale beam-column tee-joint specimens were tested under monotonic and cyclic loading in two groups. As a parameter, the rear face of the SHS column in the area of the connection was reinforced by backing plates in the second group of specimens. The results obtained are provided in terms of moment-rotation relationship and energy dissipation capacity. All specimens reached beam plastic load level at high deformation levels. Reinforcing the SHS column rear face with a backing plate resulted in an increase in strength and initial stiffness but a reduction in the energy dissipation capacity of the joint. Considering the overall cyclic performances, both joints maintained high plastic rotations in adequate resistance levels with acceptable energy dissipation capacities; consequently, they are suitable for use as semi-rigid partial strength joints in simply designed, braced steel frames in seismic regions or in unbraced steel frames in regions with less seismic activity. Additional component tests were carried out to understand better the component behaviour of the hollow section face in bending and to try to design component modelling parameters. The influence of bolt spacing and the distance between bolt rows on the resistance of the square hollow section face in bending was examined. As expected, when the bolts were closer to the sidewall, the resistance of the face increased.