Slip factor of high strength steel with inorganic zinc-rich coating

Abstract

Abstract The loading resistance of slip critical steel connection is determined by the slip factor between faying surfaces and pretension force in bolts. The shot-blasting treatment is a commonly used and simple type of surface treatments. In order to avoid the risk of rusting of shot-blasted surfaces which threatens the structure safety, shot-blasted surfaces are generally coated with aluminum or zinc-based product. In this study, the slip factors of high strength steels (Q550, Q690 and Q890) with inorganic zinc-rich coating are investigated. Two values of coating thickness (60 μ m and 80 μ m ) are selected and the influence of thickness of coating on slip factor is studied. Based on classical friction mechanism theory, compared with slip factor of shot-blasted surface, the decreasing of slip factor of surface with inorganic zinc-rich coating is analyzed. Moreover, the coating thickness effect on slip factor is also investigated. Because the difference between the measured slip displacement at 5 min (short-term tests) and 3 h (long-term tests) exceed 2 μ m , corresponding creep tests are carried out to evaluate long-term effects. Based on tests results, the recommended values of slip factor of high strength steel surface with inorganic zinc-rich coating is 0.30.