AbstractThe postyield ductile damage of steel structures is gaining the interest of researchers and designers alike. The ability to model and quantify the damage of structural steel is the focus of this research and a novel approach that relies on micromechanical theories is presented to develop the finite element (FE) model for the ductile damage of double Tee and extended endplate connections. First, a methodology is presented to guide researchers and designers on how to model the FE fracture of steel material subjected to combined tensile and shear loadings using two built-in ductile damage models in ABAQUS [the Stress Modified Critical Strain (SMCS) and the Hooputra models]. Second, several steel base materials (A992, A572-50, and A36) and bolt materials (A325 and A490) are calibrated for use in both ductile damage models (SMCS and Hooputra). Third, FE fracture models are developed and validated against experimental results, available in the literature, of double Tee and extended endplate connections subjected to monotonic and cyclic loadings. The results show that the proposed FE fracture model predicts the failure mode and load-displacement response of double Tees and extended endplates with at most 9.5% deviation for the displacement at fracture and 7.8% deviation for the ultimate load. The FE fracture model predicts the postultimate strength and ductility required for seismic applications. Also, the FE fracture model predicts crack initiation in base or bolt material due to tensile and/or shear loadings. In a broader perspective, this research enables design engineers to accurately predict the postultimate behavior of steel connections with ease. The research also aims at including the fracture characteristics of steel material in the current design guidelines of steel connections.

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