Characterization of impact-induced forces and damage to bridge superstructures due to over-height collision

Abstract

Over-height collisions into bridge superstructures often lead to structural damage, posing an immediate risk to the safety of motorists and functionality of bridges. To ensure that the bridge girders impacted by over-height vehicles are not compromised, it is essential to have an accurate assessment of the impact-induced loading demand. The current codes and specifications, however, lack the information necessary to estimate the impact forces that the bridge girders can experience during an over-height collision. To address this gap, a detailed investigation is conducted in the current study to (i) characterize the loading demand expected from various impacting objects, (ii) determine the range and variability of impact-induced forces (as a function of the velocity and size of the impacting objects), and (iii) develop a set of equations to predict the impact forces from over-height collisions into bridge superstructures. For this purpose, high-fidelity finite-element (FE) models are developed, covering four individual objects, i.e., concrete pipe, steel tank, PVC pipe, and wooden box container, in addition to a tractor-semitrailer. The structural performance of the bridge superstructures impacted by the identified objects is evaluated using several response measures, including impact force, internal shear, and damage pattern. The outcome of this study provides the input necessary for the design of new and the assessment of existing bridge superstructures against possible over-height collisions.