Numerical study of block shear limit state in welded gusset plates

Document Type : Research Article

Authors

1 Department of Civil Engineering, Sharif University of Technology

2 CE Dept., Sharif University

Abstract

The block shear failure is a common limit state that governs the base metal strength in welded connections. The framework for block shear strength prediction adopted by current design specifications is originally based on research results on bolted joints. Also, in the past few studies conducted on welded connections, the mechanical properties of the steel used are distinct from the commonly applied steel in Iran. In this paper, first, a nonlinear finite element model with ductile damage capability was developed and validated against available test results on welded gusset plate connections. Then, a parametric study was performed on connection length, connection width, welding configuration, and gusset plate thickness, in which, the strain and stress distribution, as well as the block shear rupture path, were investigated. The results showed that the mechanics of block shear failure in welded connections is different from bolted ones for reasons like stress triaxiality development in tensile failure plane due to the existence of additional constraint against necking of base metal fibers adjacent to the weld. Evaluation of existing block shear strength equations revealed that the AISC block shear design equations provide so conservative capacities, on average 36%, for welded connections. Accordingly, a new block shear strength equation was developed, such that, the predicted nominal block shear strengths are on average about 5% on the conservative side, however, Using the LRFD load and resistance factors in the design along with this equation, the safety needed for this limit state is ensured.

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