Insights into failure in hybrid joints on galvanized steel

Hybrid joints, which combine adhesive bonding with pretensioned bolts, offer significant advantages in terms of enhanced strength and simplified manufacturing processes, if compared to simply bonded. However, bonding on galvanized steel presents unique challenges due to the presence of corrosion-resistant coatings that can negatively impact adhesive performance. This study investigates the performance of hybrid joints using two epoxy adhesives, Scotch-Weld7240 (SW7240) and SikaDur-370 (S370), focusing on the differences in load-bearing capacity between galvanized and non-galvanized steel substrates. Experimental results reveal that both adhesives exhibit substantially lower load capacities on galvanized surfaces, with reductions of approximately 26% for SW7240 and 57% for S370. Predictions with a probabilistic approach underestimated the experimental values by approximately 9% for SW7240 and 10% for S370. These findings underscore the critical influence of surface treatment on hybrid joint performance and highlight the necessity for optimized adhesive formulations tailored for galvanized steel applications to improve bonding efficacy and overall reliability.