Mechanical behavior of hybrid joint with bearing-type and slip-critical bolted connections

Abstract

In recent years, high-strength bolts with slip-critical joints have been lengthened owing to the impact of increased traffic loads and the need to rationalize steel members. However, as the length of the joint increased, the force that the bolted joint could resist decreased, because the distribution of the bolts inside the joint became uneven. Moreover, owing to the presence of secondary members in the vicinity of the joint, the length of the splice plates was limited. Therefore, it is necessary to shorten the joint length while maintaining its design strength. This study presents a method that uses a Interference body bolt arrangement at both ends of a long-bolted joint (hybrid joint) to improve joint strength. Finite-element (FE) analysis was conducted to investigate the load-sharing mechanism and slip strength of the hybrid joint. The numerical analysis results showed that 12-row hybrid joints could improve the slip load by approximately 20% compared with 12-row friction-bolted joints. We found that a hybrid joint with Interference body bolts can effectively improve its slip strength and shorten the length of the slip-critical bolted joint. Furthermore, we defined the serviceability limit state of the hybrid joint as the bolt shear yield of the bolt shank or the net cross-sectional yield of the plate. Additionally, we presented an equation to evaluate the bolt shear yield strength of a hybrid joint. Both the errors in the analysis results and the calculated values were less than 5%.