Methodology for Predicting the Alternate Block Shear Failure of Beams in Bolted Flange Plate and Double Tee Moment Connections

Abstract

This study investigates the alternate block shear (ABS) failure in bolted flange plate (BFP) and double Tee moment connections. ABS, not yet included in the AISC 358 specifications, is a failure mode that combines full tensile fracture in the beam flange with shear failure in the beam web. After validation with experimental results, finite element (FE) models are developed to examine ABS failure in BFP and double Tee moment connections. The dimensionless ratio of connection length to beam depth ratio is considered the major parameter for identifying the governing failure mode. Experimental results available in the literature and FE results conducted in this study are compared with existing strength models to investigate their prediction capabilities. A proposed methodology is presented through a stiffness based model to predict the failure path and mode. Adding the ABS failure check to the current US building standards is recommended to ensure a safe design.