Effect of Cope Hole Radius on Fracture Resistance of Moment Frame Beam-Column Connections under Seismic Loading

Abstract

Welded steel connections are commonly used in buildings located in areas with high earthquake risk. Weld sizes are designed to handle the maximum expected force, and specific materials are covered by specific requirements. However, some types of connections may still suffer Ultra-Low Cycle Fatigue (ULCF) fracture during earthquakes.

This study uses ABAQUS software to analyse ULCF fractures in beam-column welded connections with cope holes. A new fracture model is introduced that is both accurate and easy to use. It is validated using four small test samples and one large welded connection. The model creates relationships between strain demand (A) and the number of cycles to failure (N), known as A-N curves, using both kinematic and isotropic hardening. The results show that the model reliably predicts how steel fractures under stress. These A-N curves are useful tools for estimating how much earthquake life remains in structural steel, due to their accuracy and consistency.