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INSTRUCTORS:
David Jacobs, Ph.D., P.E., F.ASCE
Samuel C. Krist
Ahmed Ibrahim
Course Length: 1 hour
Purpose and Background
These presentations were recorded at Structures Congress 2026.
Slow Speed Impact on Railroad Bridges (25 minutes)
Railroad bridges experience dynamic loads whenever trains cross, and understanding these impacts is critical for maintaining safe and reliable structures. This presentation examines an extensive field study conducted on a heavily traveled railroad bridge located on the Northeast Corridor. Researchers evaluated the effects of slow-speed passenger train traffic using strain gauges, accelerometers, and displacement measurement systems. The study investigated how bridge span length, train characteristics, and speed influence dynamic impact forces and bridge behavior. Results were compared with existing AREMA impact provisions to determine whether current design assumptions accurately reflect actual field performance. The findings provide valuable insight into bridge fatigue, maintenance planning, and the long-term management of aging railroad infrastructure.
Bridges Subjected to Impact, Vessel Collision, and Flood (12 minutes)
Bridges crossing navigable waterways face unique hazards, including vessel collisions, flood events, and changing maritime transportation demands. This presentation reviews AASHTO vessel collision provisions and evaluates how modern shipping trends affect bridge risk assessments. The discussion explores the increasing size of commercial vessels resulting from expansions of the Panama and Suez Canals. Attendees will learn how collision forces are estimated using probability-based approaches and kinetic energy calculations. The presentation also examines mitigation strategies used to protect bridge substructures from vessel impacts. Practical examples demonstrate how bridge owners can address changing risks throughout a bridge's service life.
Enhancing The Resilience of Prestressed Girder Bridges Against Over-Height Vehicle Collisions (22 minutes)
Over-height vehicle collisions are a frequent source of bridge damage across the United States and can significantly affect the safety and serviceability of prestressed concrete bridges. This presentation summarizes a comprehensive research program involving full-scale testing and advanced finite-element simulations. Researchers evaluated the behavior of prestressed girder bridges subjected to lateral impacts from trucks traveling at various speeds. The study examined damage mechanisms, residual structural capacity, and the effectiveness of bridge diaphragms as mitigation measures. Numerical models were validated using experimental data to improve confidence in predicting bridge performance during collision events. The findings can help agencies develop more resilient bridge designs and implement practical collision-prevention strategies.
Benefits and Learning Outcomes
Upon completion of this course, you will be able to:
- Describe the factors that influence dynamic impact forces on railroad bridges.
- Explain how field monitoring data can be used to evaluate bridge performance and fatigue behavior.
- Identify the key factors used in assessing vessel collision risk for bridges.
- Explain how changes in vessel size influence bridge collision demands and protection strategies.
- Describe the structural effects of over-height vehicle impacts on prestressed concrete bridge girders.
- Identify mitigation measures that can improve bridge resilience against vehicle collisions.
Assessment of Learning Outcomes
Students' achievement of the learning outcomes will be assessed via a short post-test assessment (true-false, multiple choice, and/or fill in the blank questions).
Who Should Attend?
- Structural Engineers
- Forensic Engineers
- Bridge and Transportation Engineers
- Engineering Managers/Principals
- Building Design and Construction Professionals
- Researchers and Engineering Students
How to Earn your CEUs/PDHs and Receive Your Certificate of Completion
To receive your certificate of completion, you will need to complete a short on-line post-test and receive a passing score of 70% or higher within 365 days of the course purchase.
How do I convert CEUs to PDHs?
1.0 CEU = 10 PDHs [Example: 0.1 CEU = 1 PDH]