All ETDs from UAB

Advisory Committee Chair

Nasim Uddin

Advisory Committee Members

Christopher Waldron

Jason Kirby

Mohammad Haider

Ashraf Al-Hamdan

Document Type

Dissertation

Date of Award

2019

Degree Name by School

Doctor of Philosophy (PhD) School of Engineering

Abstract

Multiple hazards (e.g., earthquake, wind gust, flood, vessel collision, traffic overload and accidents, and terrorist attacks, etc.) must be properly considered in highway bridge design in addition to the normal functionality requirements. Unfortunately, the structural health of bridges are continuously deteriorated over time, this in tandem with an excessive increase in hazard events, which makes the network extremely vulnerable to natural hazards. The main goal of this dissertation is to provide methods to investigate bridges safety against multi-hazard by obtaining load scenarios and evaluation of the performance based on these loads. Hazard events have been divided into routine events and extreme events. Each part has been divided into Loading and assessment. The loading part aims to better understand current loads, how it grows, prevent, and resist it if it is possible. The assessment part is aiming to check bridges safety and suggest solutions to maintain the healthy case. Routine events are presented by overloaded truck, while extreme events presented by Hurricanes and earthquakes. The first step to assess the bridge safety against overloaded trucks is to evaluate the transit traffic weight and its relation to bridge strength. In this regard, the B-WIM algorithm is used to estimate the weight of the passing trucks to prevent the overloaded truck from crossing over more bridges. The current B-WIM algorithm has some limitations that prevent it from being a tool of enforcement. Therefore, this dissertation presents new algorithms that enhance the performance of the B-WIM system. First, A) the effect of the aside traffic is removed to increase the accuracy of the calculated truck weight. B) Solve the multiple-presence problem. C) A novel technique has been used to reduce the B-WIM algorithm computational time to the real-time level, which makes it possible for “real-time Bridge Weigh-In-Motion.” D) Acceleration based B-WIM system has been introduced in this dissertation by using acceleration measurements instead of strain measurements as input for B-WIM system. Kalman filter based algorithm has been used for this purpose. E) An innovated method has been developed to reduce the number of sensors used in the B-WIM system. F) B-WIM algorithm has been used as an assessment tool to detect the bridge damage. For the extreme events, a simulation-based and time history analysis methods are used to calculate the hurricane and the seismic load. The assessment part focuses on evaluating the super-structure to sub-structure connection against these loads. The hurricane forces have been calculated using the Computational Fluid Dynamics (CFD) simulation instead of using empirical formulas. The CFD simulation has been performed and validated by utilizing other researchers experiment. The time-history analysis is used to explore the safety of the bridge/pier connection under hurricane loads. Further, the simulation has been extended for a large-scale bridge model. Earthquake loads are calculated using explicit LS-Dyna FE solver. A three-dimensional (3-D) bridge model has been utilized to represent the bridge with an exact representation of the bridge geometry and the soil material. A scaled real ground excitation has been induced to the soil substrate to mimic the earthquake event. The preliminary results are used to investigate the AASHTO requirements for seat length, and to check the sub-structure super-structure connection.

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