Slip‐resistant bolted connections of stainless steel

Abstract

The use of stainless steel components can lead to a significant reduction of maintenance costs compared to a structure executed in carbon steel. Because of its high material strength, ductility and corrosion resistance stainless steels are becoming more and more popular as a construction material in both building and civil engineering structures. Consequently slip-resistant bolted connections made of stainless steel are becoming more important. Slip-resistant bolted connections are used in joints where slip is not acceptable (because they are subject to reversal of shear load or any other reason) or in joints that are subject to cyclic shear load (to improve the fatigue class of the connecting plates). Existing design codes/standards do not specify slip factors for surface treatments of stainless steel grades, the minimum values of slip factors for common surface treatments/coatings that are specified in EN 1090-2 are exclusively valid for carbon steels. One of the reasons for this is that stainless steel alloys are thought to suffer more than carbon steels from time dependent behaviour (creep and relaxation) at room temperature. This could lead to higher preload losses and consequently to lower slip factors than used for carbon steels with comparable surface treatment. However, no evidence of this can be found in literature. Creep and relaxation are stress dependant phenomena and the stresses in the components of preloaded bolted connections are locally highly non-uniform. Therefore, slip factors of different stainless steel grades have to be determined by experiments to investigate the effects of time dependant material behaviour. In this paper the results of slip factor tests on four stainless steel grades are presented and the influence of surface treatments and the preload level on the slip factor of stainless steel slip-resistant connections is discussed.

Experimental Study On The Slip Resistance, Bolt Relaxation And Fatigue Behaviour Of ASTM A1010 Stainless Steel For Bridge Applications

“…58.87 µm (2.32 mils) Note: 25.4 µm = 1 mil (thousandth of an inch) Figure 4-3 shows a comparison between the slip resistance coefficient obtained in the current study and those available in the literature for different stainless steel types and different faying surface conditions (Stranghöner et al, 2017). The bar graph shows that the slip resistance coefficient obtained in this study for ASTM A1010 is much lower than those obtained by Stranghöner et al (2017) for grit blasting. It is important to distinguish the fact that the study by Stranghöner et al used the testing method described in Annex G of EN 1092, which is a common test method performed on the tensile direction amongst European nations.…”

“…This is important to note because the average bolt clamping force from turning the nut 120° from snug tight condition measured by Cameron (2017) in the Skidmore-Whilhelm load cell was 203 kN. 58.87 µm (2.32 mils) Note: 25.4 µm = 1 mil (thousandth of an inch) Figure 4-3 shows a comparison between the slip resistance coefficient obtained in the current study and those available in the literature for different stainless steel types and different faying surface conditions (Stranghöner et al, 2017). The bar graph shows that the slip resistance coefficient obtained in this study for ASTM A1010 is much lower than those obtained by Stranghöner et al (2017) for grit blasting.…”

“…This is contrary to what is believed for regular carbon steels. Figure 2-32 summarizes the slip resistance coefficients for different stainless steel grades and surface treatments using Class 8.8 stainless steel bolts (Stranghöner et al, 2017).…”

“…Figure 2-27: Slip Load Definitions (RCSC, 2014) ------------------------------------------------------Figure2-28: Standard Test Specimens for Slip Factor Test EN1090-2(Stranghöner et al 2017) …”

Vorgespannte Schraubverbindungen aus nichtrostendem Stahl

“…Die Untersuchungen zur Bestimmung möglicher Haftreibungszahlen wurden zwischen zwei der beteiligten Forschungsstellen aufgeteilt. Alle Versuche mit Bumax 88 Schraubengarnituren wurden am Institut für Metall‐ und Leichtbau der Universität Duisburg‐Essen (UDE) durchgeführt, die Versuche mit Bumax 109 Schraubengarnituren am Lehrstuhl für Stahl‐ und Verbundkonstruktionen der Technischen Universität Delft (TUD) .…”