Date of Award

12-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil Engineering

First Advisor

Robert J. Connor

Committee Chair

Robert J. Connor

Committee Member 1

Mark D. Bowman

Committee Member 2

Justin M. Ocel

Committee Member 3

Amit H. Varma

Abstract

Currently, all steel bridges with members designated as Fracture Critical Members (FCMs) are required to undergo hands-on inspections every 24 months. A FCM is a primary steel tension member (or portion of) which failure results in collapse or loss of serviceability of a bridge. However, presently, there are no codified procedures used to evaluate system-level redundancy in steel bridges. In this dissertation, finite element analysis (FEA) procedures, techniques and inputs were researched in order to develop bridge models that account for the mechanisms that lead to redundant capacity after the failure of a primary steel member. These mechanisms include partial composite action between the slab and steelwork and other phenomena not typically considered in current practice. The researched set of FEA procedures, techniques and inputs were benchmarked against available field experimental data and used to characterize the dynamic effects due to sudden failure of a primary steel member. The FEA methodology was completed with reliability-based load combinations describing the loading conditions a steel bridge must sustain after the failure of a steel tension member in order to be considered redundant, and a set of minimum performance requirement that ensure adequate strength and serviceability of a steel bridge in the faulted condition. The application of the developed FEA methodology in conjunction with existing rational methods for determining the hands-on inspection interval results in a comprehensive approach to efficiently maintain an inventory of bridges with members that are currently designated as FCMs.

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