Experimental study on stainless steel high-strength bolted slip-resistant connections

Abstract

Stainless steel structures have broad application prospects owing to their excellent corrosion resistance and mechanical properties. Current studies on stainless steel structures mainly focus on material properties and member behaviors. Several studies have reported on the performance of stainless steel joints and connections. In this study, a series of tests were performed on two fundamental parts of the stainless steel high-strength bolted slip-resistant connection, that is the stainless steel high-strength bolts and stainless steel faying surface treatment. For the stainless steel high-strength bolts, the tests were conducted on six types of bolts, including a new type of high-strength bolt made of S17400. The chemical compositions and full-range stress-strain curves were reported. The friction coefficients of the bolts with and without lubrication were measured. It was concluded that thread galling would probably occur during the application of the preload for bolts without lubrication. Lubricants would smoothen the tightening process and reduce the friction coefficient considerably. With regard to the stainless steel faying surface treatments, a total of eight types of treatment methods categorized into four groups were investigated. The surface roughness and slip factor were measured. It was concluded that under the commonly used steel structure faying surface treatments, the slip factor of the stainless steel plate was much lower than that of the carbon steel plate. The methods of clamping soft metal plates between the grit blasted stainless steel surfaces could improve the slip factor to approximately 0.30; a higher slip factor with a comparatively lower surface roughness would be obtained with the coating method. The proposed heavy brushing and mechanical scoring methods could considerably increase the surface roughness and slip factor. In addition, the slip factor was positively correlated with the surface roughness for most of the faying surfaces. The results of this study could benefit the development of related design codes.