Experimental Study on the Shape Improvement and application of High Tension Counter Sunk Head Bolts in Friction Grip Joints

Abstract

Creep and relaxation occur after High Tension Bolt (HTB) tightening causing shaft tension loss and further stress redistribution in the connected components. Past research has shown that ductility improvement and shaft tension loss control can be achieved by waisting the HTB shank. With the further modification of making the HTB head plate shaped counter sunk Head plate bolt with an aesthetically pleasing, flat surface less susceptible to rain corrosion results. In this research, tensile, relaxation and friction grip joint slip experiments are done on waisted shank, counter sunk head HTB to ascertain the ductility improvement, the resulting decrease in shaft tension loss and its magnitude, as well as their applicability in friction grip steel connections.