Viscoplastic deformation behaviour of preloaded stainless steel connections

Abstract

Preloaded bolted connections made of stainless steel are not commonly used in stainless steel structures as their application is not allowed by the execution standard EN 1090–2 and the design standard EN 1993-1-4 for stainless steel structures unless otherwise specified, respectively unless their acceptability for a particular application has been demonstrated from test results. This restriction is mainly caused by three facts: firstly, it is feared that due to the viscoplastic deformation behaviour of stainless steel, severe preload losses have to be expected, secondly, neither stainless steel bolting assemblies for preloading nor tightening procedures exist on which could have been relied and thirdly, galling and seizure of stainless steel bolting assemblies lead to problems on site. These three questions, beside others, were treated in the frame of the European RFCS-research project “Execution and reliability of slip resistant connections for steel structures using CS and SS” SIROCO. Some of the results are presented in this contribution with the main focus on the loss of preload of preloaded stainless steel bolted connections. The main conclusion is that preloaded stainless steel bolted connections can be treated similar to those made of carbon steel with regard to preload losses as they show comparable magnitudes of preload losses.