Dissertations and Theses

Date of Award

2019

Document Type

Dissertation

Department

Civil Engineering

First Advisor

Anil Kumar Agrawal

Second Advisor

Sherif El-Tawil

Keywords

Truck impact, Bridge pier, Performance-based design, Risk-based design

Abstract

Based on bridge failure data compiled by the New York State Department of Transportation, collision, both caused by vessels and vehicles, is the second leading cause of bridge failures after hydraulic. The current AASHTO-LRFD (2017) specification recommends designing a bridge pier vulnerable to vehicular impacts for an equivalent static force of 2,670-kN (600 kips) applied in a horizontal plane at a distance of 1.5 m (5.0 feet) above the ground level. The vast majority of research studies on vehicular collision with bridge piers have been carried out with single-unit trucks, which are typically classified as medium-duty vehicles weighing about 89 kN (20,000 lb). Yet, collision events that involve severe bridge damage are generally caused by heavy-duty trucks, generally tractor-semitrailers weighing 360 kN (80,000 lb). The handful of tests that were conducted to study heavy truck collision employed rigid piers, which means that the deformation and failure mechanisms of the piers were neglected. This study proposed a performance-based approach for designing a bridge pier subject to impact by a tractor-semitrailer weighing up to 360 kN (80,000 lb) based on a computational investigation. Validated, high-fidelity finite element simulations of collisions between tractor-semitrailers and reinforced concrete bridge piers have been carried out to investigate the demands imposed upon, and damage modes of, concrete piers. Through extensive numerical simulation of heavy vehicle (tractor-semitrailer) impacts on piers, the impact force time histories were simplified in the form of analytical triangular pulse functions. The parameters of these functions were derived through numerical regression based on the simulation results. A performance-based approach that relates demands (in terms of the applied force time histories) and capacity (in terms of acceptable shear distortion and plastic rotation) was proposed for the design of bridge piers vulnerable to heavy vehicle impact. Since many collision failures have been observed to be dominated by shear failure, the proposed performance-based approach used capacity-design concepts from earthquake engineering to mitigate collapse by minimizing shear distortion of piers impacted by heavy vehicles. Simulation results in this study have shown that the capacity design method can significantly reduce the shear distortion in the piers when subject to heavy truck impact. The risk of pier collapse in a given impact event was also evaluated based on Monte Carlo simulations, and a risk-based design framework was proposed in this study. The proposed risk-based design approach can serve as a powerful tool for the bridge owners to leverage the capacity of bridge piers and the risk of bridge damage caused by the impact event.

Available for download on Thursday, July 29, 2021

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