A Model for Prediction of Fracture Initiation in Finite Element Analysis of Bolted Steel Connection

This paper studies the finite element prediction of fracture initiation in bolted structural steel connections using damage mechanics. A material failure envelope has previously been developed for aluminum extrusions using the IDS (instability, ductile, and shear) criterion. The IDS criterion is a damage mechanics based model for defining failure envelopes. These failure envelopes are adjusted to match first fracture in three different common steel connection components comprising a total of five different materials. This includes bars of A36 and A588, T-sections of A992, and bolts of A325 and A490 material. Components were tested in uniaxial tension and/or shear and found to match favorably with experimental results. Four full scale beam-to-column connections were modeled using the failure envelopes developed from the components to verify the procedure. These included two bolted T-stub connections and two top-and-seat angle connections. Load-displacement curves for the full scale models were found to coincide with experimental results.