Optimization of Composite Bridge Design Using High-Frequency Mechanical Impact: A Case Study

Paper in proceeding, 2026

Bridges are usually subjected to cyclic loading that can lead to irreversible fatigue damage, especially in welded joints, which are therefore critical to structural integrity. High-Frequency Mechanical Impact (HFMI) treatment is a promising post-weld treatment method that significantly enhances fatigue resistance by improving the local geometry and inducing beneficial residual stresses. The method has proven potential for fatigue strength improvement of both new and existing structures. However, the application of this method to bridge structures, while accounting for design considerations specific to HFMI treatment, has been only sparsely addressed in the existing literature. This study investigates the possibility of optimizing a case study steel bridge design with HFMI treatment in addition to higher-strength steel. The results show that using HFMI treatment improves overall fatigue performance and significantly reduces utilization ratios for fatigue limit state. For the bridge studied, steel grade S460 is found to be the most cost-effective option. In the end, the study shows that using higher-strength steel with HFMI treatment in new bridge design can result in significant advantages, such as material and cost savings.