Full-range behavior of bolted connections with oversized holes

Bolted connections with oversized holes are getting increasing attention especially in prefabricated steel structures, largely because of their larger tolerance for potential assembly imprecision. While focus of previous studies on oversized holes was mainly given to the initial slip resistance, the behavior of the connections after bolts bearing on the holes has not been adequately considered. A total of 15 bolted connection specimens with different bolt hole sizes were tested from initial slip to complete fracture in different failure modes. Test results showed that oversized holes had a less effect on the initial slip resistance of the specimens than expectations of Eurocode 3, and increase in bolt hole size decreased the resistance of the specimens at the bearing stage. Finite element (FE) models were created to simulate the full-range behavior of the specimens, and a parametric analysis was conducted to further investigate the combined effect of assembly misalignment and oversized holes on the connections' resistances during the bearing stage. It was found that the Eurocode 3 design equations could give reasonable predictions of the ultimate resistance for the models, but fail to predict the resistance at the serviceability limit state (SLS) where the excessive deformation is limited. The average ratio of numerical simulation result to model prediction on the SLS resistance is 1.01 but with a relatively large CoV of 0.121, indicating that Eurocode 3 yields unsafe predictions for a large portion of the connections. A modified factor was accordingly proposed to achieve more accurate predictions.