Dr. Scott Walbridge
P.Eng. (Alberta)
Assistant Professor
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RESEARCH
GROUP:
Publications
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Research Group:
Past Projects:
Fatigue Testing and Analysis of Bridge Welds Retrofitted by Needle Peening
Collaborators: Prof. K. Papoulia, K. Ghahremani (M.A.Sc.)
Financial Support: CISC (SSEF), NSERC
Brief Summary: In this project, fatigue tests were conducted of as-received and needle peened structural steel welds under simulated in-service loading conditions typical of highway bridges. In addition, fatigue tests were performed of needle peened specimens treated under load; simulating the retrofitting of a welded structure, with the stresses due to the self-weight of the structure superimposed. During the fatigue testing, the crack growth was monitored using an AC Potential Drop (ACPD) device. In addition to the fatigue testing, the microstructure of the treated welds was examined and microhardness and residual stress measurements were performed. Following the laboratory work, the test results were predicted by a strain-based fracture mechanics analysis, and a preliminary study was performed wherein a cohesive zone model was used to model crack growth through a residual stress field.
Fatigue Testing and Analysis of Aluminium Bridge Welds
Collaborators: R. Coughlin (M.A.Sc.)
Brief Summary: This project consisted of an investigation of the fatigue behaviour of structural aluminium welds under in-service highway bridge loading conditions. Within the scope of this investigation, calculations were performed to establish new damage equivalence factors for aluminium for use with the AASHTO and CAN/CSA-S6 codes. Following this, small-scale fatigue tests of aluminium welds under simulated highway bridge loading conditions were conducted. In addition to the fatigue testing, micro-hardness and residual stress measurements were performed on the aluminium weld specimens. A fracture mechanics model was then validated and used to perform simulations encompassing a wider range of loading conditions.
Fatigue Retrofitting of Welded Steel Cover Plates using Pre-Stressed CFRP Strips
Collaborators: Prof. K. Soudki, F. Vatandoost (M.A.Sc.)
Brief Summary: This project was undertaken with the objectives of: 1) fatigue testing steel beams with welded cover plates strengthened using pre-stressed CFRP strips, and 2) employing analytical models to predict the resulting fatigue life increase. Fatigue tests were performed on six large-scale specimens, reinforced with pre-stressed CFRP strips at two locations, and having several different elastic moduli and pre-stressing levels. The test results were predicted by a fracture mechanics model, wherein the stresses in the weld were determined by finite element analysis.
Predicting and Prolonging the Service Lives of Corroding Weathering Steel Bridges
Collaborators: Prof. C. Hansson, N. Damgaard (M.A.Sc.), J. Yeung
Financial Support: MTO
Brief Summary: This project included three studies, undertaken to investigate various issues related to the corrosion of weathering steel highway structures. The first study examined the effects of corrosion products and pitting on weathering steel plate thickness measurements obtained using a standard ultrasonic gauge. The second evaluated the potential of several zinc-based coatings, including metallizing and zinc tape, as a way of protecting elements of existing corroded structures. The third study comprised a series of reliabilityanalyses of composite weathering steel overpass structures with uniform corrosion occurring at various locations and rates.
Development of a Shear Connection for a Portable Composite Bridge
Collaborators: Prof. J. West, M. Bowser (M.A.Sc.)
Financial Support: NSERC, Surespan Inc.
Brief Summary: In order to enable a portable composite bridge, this study proposes and evaluates alternatives for providing a shear connection between steel girders and pre-cast concrete deck panels, which allows the fastening and unfastening of these components. Finite element (FE) analysis was employed to compare the performance of the preferred composite system to a conventional composite girder with ductile shear studs. A non-linear analysis was performed, and the preferred composite system evaluated. The FE model was verified for its ability to capture the possible effects of flange buckling, web buckling, and lateral torsional buckling of the girder. A parametric study was also performed, in which the effect of shear connection stiffness and spacing on the behaviour of the composite girder was investigated.
Aluminum Highway Bridges: Design and Life-Cycle Cost Analysis
Collaborators: Prof. A. Nussbaumer (EPFL), G. Sollet (Master’s, EPFL)
Brief Summary: For this project, a program was developed to facilitate the design of aluminium highway bridges using a draft version of the new Canadian Highway Bridge Design Code (CSA S6) chapter on aluminium structures. A life-cycle cost analysis of several bridge variants was then performed including different combinations of steel and aluminium girders and concrete and aluminium decks.
