Effects of Bolt Spacing On Prying Forces in WT Connections

WT connections are commonly used within the structural steel frame. These connections may be used as a hanger connection or as a flange connection element in a moment connection. When the flange of a WT shape is bolted to a column or a beam and the WT stem is subjected to a tensile loading, the tensile force in the bolts can increase due to prying action. Although prying action in tees is a well-studied phenomenon, current design provisions do not directly address how increasing bolt spacing parallel to the WT stem impacts prying force. This experimental study focuses on the effects of changing bolt spacing parallel to the stem when the tee is subjected to a tensile force. A total of ten tests were conducted considering WT specimens with two different flange thicknesses and five different spacing between the bolts. Bolt forces, determined from strain measurements, were compared to the applied tensile force to determine the magnitude of prying force. Displacement measurements were also taken and deformation demand was quantified and correlated to prying force. Experimental tests show that bolt spacing parallel to the WT stem affects prying force in the bolts. As bolt spacing increases, prying force decreases. As would be expected, WT flange thickness affects deformation and plays a role in the magnitude of the prying force. Trends regarding bolt spacing are consistent when comparing the WT specimens with different flange thicknesses.