Fatigue life of the bolted yoke connection in single support beam (SSB) modular bridge expansion joints

The objective of this article is to demonstrate a comprehensive procedure for the estimation of the fatigue life of the component centre-beam-to-support-beam (CB/SB) bolted yoke connection. In this procedure, all the aspects are included such as fatigue vehicle loading, cycles per truck passage, lifetime average daily truck volume, fatigue classification of the detail and determination of fatigue infinite life. A typical single support beam (SSB) steel modular beam expansion joint (MBEJ) was modelled as 3D space frame. Moreover, three F.E. sub-models were created for the simulation of the (CB/SB) bolted yoke connection with preloaded bolts M16, M20 and M22 respectively. The Fatigue Load Model 2 (FLM2), recommended in EN 1991-2:4.6.4 for infinite fatigue life was chosen for the fatigue verification of the bolted yoke connection detail, assumed to be travelling at 90 km/h over the expansion joint. The 3D space frame was analysed by using Time-history dynamic analysis and thereafter, the calculated outputs were introduced in the F.E. sub-models. From the analysis of the sub-models the stress ranges were obtained and the fatigue evaluation of the yoke joint was performed. The investigation shown that poor detailing at the connection between the centre-beam-to-support-beam (CB/SB) bolted yoke connection is susceptible with reference to fatigue. Finally, important conclusions were extracted for both the behaviour of the entire modular joint and the fatigue life of the bolted yoke detail.