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Abstract
A large amount of research has been performed on prying action since the 1950’s which led to modern design procedures. However, many unknowns still exist. One of the unknown considerations is the effect that bolt spacing has on prying forces. This study focused on the effects of bolt spacing in a tee connection subjected to tensile force.
The variable in the experiment was the bolt spacing, and the experiment determined how the prying forces change as the bolt spacing changed. A secondary consideration was to determine and/or validate the idea of the moment at the bolt line be greater than that of the moment at the WT shape’s web face, which is a variable in the current design procedure.
The American Institute of Steel Construction provides code provisions for which prying forces are determined. Based on those provisions, the bolt spacing for testing was determined.
In order to properly determine the effects of the prying force with regards to the bolt spacing, the bolt forces were determined using strain measurements from the bolts. Through data analysis, the prying force was determined and a comparison of five specimens was performed.
Results showed that the prying forces dropped considerably as the bolt spacing increased. The first test specimen had a bolt spacing of 5.25 inches and experienced prying forces larger than that of the AISC provisions. The cause of the large prying forces was due to alpha, a, being larger than 1.0. A significant drop in prying force occurred from the first specimen to the second specimen which had a bolt spacing of 7.00 inches. Specimen three had a bolt spacing of 8.75 inches and showed a slight decrease in prying force from specimen two. Specimens four and five which had bolt spacing of 10.50 inches and 14.00 inches, respectively, experienced approximately the same amount of prying force, which was less than that of specimen three.
It was concluded that the prying forces decrease as the bolt spacing increases, and the AISC provisions are conservative for specimens with bolt spacing greater than 7.00 inches, but unconservative for specimen one which had a bolt spacing of 5.25 inches.