Stress concentration in built-up steel members.

摘要

In the past riveting was commonly used for connecting steel structures, such as bridges. These fasteners usually develop a low and unreliable level of pretension such that the joints are assumed to behave like bearing type connections. Under cyclic loading, and depending on the stress concentration around the fastener holes, fatigue failure can occur at nominal stresses significantly lower than in members with no stress concentration. The current design standards account for this by calculating the stress range on the net section and using fatigue category B and D to assess the fatigue life for bolted and riveted details respectively. The net area used for the calculation of the stress range is based on the procedure proposed by Cochrane (the s2/4g rule), which is adequate shear type failure. Tests have shown, however, that the Cochrane approach does not apply for fatigue failure since rupture does not take place in a ductile shear mode.;An investigation into the effect of connection size and hole pattern on the fatigue resistance of built-up I section to gusset plate connections was carried out. A design equation that considers the connection size and hole layout on the stress concentration factor is proposed. An appropriate fatigue category for these members is also recommended.