Determining the preload in preloaded bolt assemblies in existing steel structures. Issue 4 (7th November 2017)

• Record Type: Journal Article
• Authors: de Vries, Peter; Nijgh, Martin; Veljkovic, Milan
• Is Part Of: Steel construction. Volume 10:Issue 4(2017:Nov.)
• Page Start: 282
• Page End: 286
• Publication Date: 2017-11-07
• Subjects: preload force -- slip‐resistant connection -- in situ measurements -- calibration factor; Tests -- Fastener; Building, Iron and steel -- Design and construction -- Periodicals; Steel, Structural -- Periodicals; Iron and steel bridges -- Design and construction -- Periodicals; Structural steel industry -- Europe -- Periodicals; 721.044714205
• DOI: 10.1002/stco.201710037
• Languages: English
• ISSNs: 1867-0520

Abstract

Abstract: Preloaded bolts are used to achieve slip‐resistant shear connections. The actual preload force in each bolt has a direct influence on the fatigue and slip resistance of the connection. The strain gauge method is examined for practical assessment of the actual preload because its use is no longer limited by the demands on adhesive curing conditions. The main objective of the paper is to describe how measured strain in the bolt shank and statistical variation of the nominal mechanical and geometrical properties of the bolt are used to determine the actual bolt preload without calibrating every single bolt. The calibration factors established by laboratory and in situ measurements exhibit rather small scatter. The minimum bolt preload required is achieved with a 95 % probability of being exceeded in a bolted connection on a Dutch highway bridge (Middachterbrug).