Testing of bolted base connections for wide-flange columns under combined axial compression and weak-axis lateral forces

Abstract

This paper focuses on a new type of base connection for wide-flange columns. The base connection consists of a pair of steel angles and a shear plate that connect the flanges and the web of a wide-flange column to the foundation through a set of high-strength bolts, respectively. To investigate the response of the bolted base connection under the combined column axial compression and weak-axis lateral load, three specimens were prepared and tested. The test parameter varied in the specimens was the technology used to develop the angles in the bolted base connection. The three specimens adopted the hot rolled angles, the angles cold folded from steel plates, and the angles welded from steel plates, respectively. All the specimens were tested with the same axial compression and the same cyclic lateral loading protocol. It was found that all the specimens behaved in the same ductile manner while dissipating significant amounts of hysteretic energy. Moreover, all the specimens sustained the weak-axis rotation of 0.06 rad without developing any in-cycle strength degradations. The tests provided clear evidence that the cold folded and welded angles can be used as the surrogates to the hot rolled angles in the bolted base connection under the considered combined loading. This research further established a simplified model to approximate the backbone response of the lateral resistance of the bolted base connection under the considered combined loading. Result comparisons show that the simplified model can provide reasonable estimates.