Numerical investigations on large size stiffened angle connections with different bolt patterns

The top-and-seat angles are commonly used in the design of beam-to-column joints, however, designing the bolt pattern is a challenge when the large stiffened angle (often connected by four or more bolts) is adopted. The purpose of this study was to propose useful design rules for such joints. The failure modes applicable to large stiffened top-and-seat angle joints are classified and formulas for calculating a so-called cruciform stub's resistance in each mode are developed. They were verified with finite element modeling after the verification of modeling method. A staggered bolt pattern is found to best exploit the combined strength of multiple bolts and avoid the premature failure of a single bolt. A method for designing the best staggered bolt pattern is developed through the analysis of key geometrical parameters using 158 simplified cruciform stubs. Failure modes and methods for calculating the tension resistance of such stubs are proposed. They provide useful suggestions for the selection and design of angle thickness and bolt type.