Impact-Induced Bridge Failures: Analyzing Structural Vulnerabilities and Optimizing Pier Designs for Enhanced Resilience

Abstract

Due to the rise in global traffic patterns in recent years, bridge failures due to impact effects are becoming an increasing concern, especially for aging infrastructure. Following the recent collapse of the Francis Scott Key Bridge, issues regarding bridge vulnerabilities and design deficiencies arose, which highlighted the need for better design codes and protection for bridge piers. This study aims to address these issues by better understanding bridges' impact-related structural failure mechanisms by developing a comprehensive optimization framework to enhance the resilience of structures to dynamic impact forces using three phases: (i) statistical analysis of bridge failure data from the Multidisciplinary Center for Earthquake Engineering Research (MCEER), with data focusing on the frequency, bridge types, and bridge material trends associated with different bridge failures across the United States, (ii) development of a compliance-based optimization for trusses using MATLAB that is applied to 2D representations of pier structures for different truss configurations (2X3, 3X4, 3X5) under stress, load, and volume constraints to simulate large magnitude impact conditions, and (iii) design and validation of optimization results through mathematical calculations of compliance and strain energy to ensure consistency between numerical results and structural mechanics principles. Both fail-safe and shape optimization strategies are employed and compared across all truss configurations, revealing distinct design methodologies between maximum and minimum compliance optimizations and the trade-offs between stiffness and energy dissipation. Maximum compliance optimization designs demonstrate increased redundancy and strain energy capacity, while minimum compliance optimization designs showed increased efficiency but were more prone to brittle failure. The final study utilizing volume constraints further examined material distribution under realistic impact loads and highlighted the importance of distributed load paths and deformation capacity in structural performance. This work provides a design framework for energy-absorbing pier geometries and aims to offer insight into improving current design standards for pier designs to account for extreme events and help guide retrofitting efforts that could prevent future failures.