Experimental study on slip performance of corroded bolted connections

Abstract

The paper presents a comprehensive experimental investigation into the slip performance of corroded bolted connections. A total of fifteen double-lap connection specimens were assembled and sixty fabricated load cells were employed to monitor the real-time preload of each high-strength bolt. Electrochemical accelerated corrosion tests were carried out to obtain connection specimens with five corrosion levels. The preload variations under indoor environment and during the corrosion tests were recorded, and shear tests were then performed on the connection specimens. It was found that the individual components in a connection specimen experienced different degrees of corrosion, with the bolt heads and nuts exhibiting the heaviest damage. The preload loss of high-strength bolts was maintained at a constant level with an average loss of 8.9 % after 45 days under indoor natural environment, while the preload loss induced by corrosion damage increased approximately linearly with the corrosion weight loss ratios. The slip loads and peak loads of connections with corrosion weight loss ratios of bolt set lower than 10 % displayed low sensitivity to corrosion damage, while the higher level of corrosion led to considerable declines in these characteristic loads. The experimentally determined slip coefficients were found to increase linearly with the development of corrosion weight loss ratios. Based on the experimental results, a predicted model for preload loss of high-strength bolts, calculation formulae for slip coefficients of faying surface, and consequently estimated methods for the slip resistances, were developed for corroded bolted connections.