Analytical and Experimental Study of Bolt Spacing Effect on Slip-Critical Connections in Steel Structures

Abstract

 Bolt steel connections using slip-critical type rely on the clamping strength of the connected surfaces due to the pre-tensioning of high-strength bolts (HSB) used, making them more complicated to apply and more expensive than bearing-type connections with bolt tightening to snug-tight conditions. However, SNI 1729:2020 and SNI 7972:2020 require that pre-tensioned bolt connections must be used at the end connections of double components and if working under vibration/dynamic loads. The purpose of this study is to conduct an analytical and experimental study of the effect of bolt spacing which means the effect of the distance of the clamping point on the shear strength of the critical slip bolt connection. The analytical study was carried out following the regulations, namely SNI 1729: 2020. Experimental studies in the laboratory used HSB A325 M-12 with 3 (three) test specimen models, each 3 (three) specimens distinguished by bolt spacing. The results of the nominal shear strength test of the critical slip connection were 73 kN for test specimen 1 (40 mm spacing) and 60 kN for test specimen 2 (70 mm spacing) and test specimen 3 (96 mm spacing). There was a change/decrease in the strength of the connection with increasing bolt spacing which means increasing the clamping distance but overall, it still met the results of the calculation of the critical-slip connection nominal strength according to provisions, which was 35.94 kN.