Cyclic testing of bolted base connections for wide-flange columns

Abstract

This research focused on a new type of bolted base connection for wide-flange columns. The base connection consists of a pair of steel angles and a shear plate that connect the wide-flange column to the foundation. To investigate the behavior of the base connection under the combined column axial compression and cyclic lateral load causing the strong-axis bending in the column, six experimental specimens were designed, constructed, and tested. The test parameters varied in the specimens included the column axial compression and the technology used to manufacture the angles used in the bolted base connection. All the specimens were tested using 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 stably achieved the ultimate connection rotation of 0.06 rad without experiencing any in-cycle strength degradations. This investigation experimentally demonstrated the replaceability of the angles in the bolted base connection. The tests also provided clear evidence that the hot rolled, cold folded and welded angles can be alternatively used in the bolted base connection to sustain the connection rotation up to 0.06 rad. This research further derived a simplified analysis model to capture the backbone response of the bolted base connection. Result comparisons show that the analysis model can provide reasonable approximations.