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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Nadim I. Wehbe


This study was performed at South Dakota State University to evaluate and mitigate the hazards to overpass bridges in the state of South Dakota towards a tractortrailer collision with one of the columns. The research comprised of three main areas: evaluation of the risk of collision and socio-economic factors associated with a collapsed bridge (performed by others), evaluation of the structural capabilities of the bridges, and experimental testing of two one-third scale bridge bents. The structural evaluation consisted of calculating the shear and flexural capacities of all the bridge columns evaluated, modeling the bridge bents in SAP2000 to determine the shear and flexural demands, and comparing the demand and capacity to determine if the bridges were capable of withstanding a tractor-trailer collision. Experimental testing was performed to investigate the effects of considering plastic events in the event of a collision and investigate a potential mitigation method. Two specimens were created as one-third scale models of an actual bridge bent for a bridge over I-29. The first specimen was an exact as-built model of the bent, while the second specimen was retrofitted with a crash strut (the potential mitigation method). The loading was applied per the guidelines provided in AASHTO LRFD Bridge Design Specifications, 6th Ed., 2012. This study consisted of: a literature review; structural evaluation; construction, instrumentation, and experimental testing of two specimens; and analysis of the experimental testing results. The results were analyzed to compare the two specimens to determine if retrofitting crash struts onto existing South Dakota overpasses would be a viable solution mitigating potential bridge collapses due to truck collisions. Results of the structural evaluation indicated that around half the bridges would not be able to withstand a bridge collision. In the experimental testing, it was found that th as-built specimen was sufficient up to a load of approximately 47% of the specified AASHTO load. The specimen with a crash strut retrofitted onto it, was found to be sufficient up to at least 150% of the AASHTO load.

Library of Congress Subject Headings

Concrete bridges -- Testing
Columns. Concrete -- Testing
Bridge failure -- Risk assessment
Tractor trailer combinations


Includes bibliographical references (pages 137-138)



Number of Pages



South Dakota State University


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