Sessions and Events

Sessions & Events 

C = Duke Energy Convention Center; H = Hyatt Regency Cincinnati

Fire and Flood Design, Performance, Mitigation, and Strengthening for Concrete Bridges

Mon, October 21, 2019 4:00 PM - 6:00 PM, C-Junior Ballroom B

Recent years have shown the potential vulnerability of concrete bridges to fire and flood hazards. Bridge fires can be caused by crashed or overturned vehicles, arson, accidents or wildfire, while flooding can be due to coastal storm surge or inland riverine and flash events. While provisions for fire and flood safety are requirement for building design, essentially no such requirements exist for concrete bridges. The proposed session will include presentations on topics related to design, performance, mitigation, and strengthening of concrete bridges for such hazards. Academic, industry and agency representatives should attend this session.
Learning Objectives:
(1) Identify the types of impacts possible on concrete bridges due to fire or flood extreme events;
(2) Summarize recent case studies on fire or flood affected concrete bridges;
(3) Discuss potential bridge design procedures for fire and flood events;
(4) Apply potential bridge strengthening and evaluation procedures for fire and flood events.

Load Testing and Rating of Fire Damaged Prestressed Concrete Bridge Girders

Presented By: Nur Yazdani
Affiliation: University of Texas At Arlington
Description: Significant investigations have been conducted on the effect of extreme load events, such as earthquake, wind and flood on bridges, as compared to fire hazards, even though fire can cause significant economic and public impacts. To bridge this knowledge gap, a full-scale one span prestressed concrete bridge was tested under a combined hydrocarbon fire and simulated AASHTO live load. The superstructure comprised of three standard I-girders, precast deck panels, cast-in-place deck, and elastomeric bearing pads. One girder was wrapped with carbon fiber reinforced polymer (CFRP), another with CFRP and sprayed fireproofing and a third was without CFRP or fireproofing. The test was conducted for 60 minutes and the fire temperature reached as high as 1131oC. It was found that the fireproofing was helpful in lowering the temperature at the CFRP-concrete interface, thereby preserving the integrity of the CFRP bonding, the concrete substrate, and prestressing steel. Without fireproofing, the CFRP quickly debonded, thereby causing significant concrete spalling and loss of some prestressing strands. Following the fire test, the deck was saw cut and each girder was tested in the laboratory under a three-point bending set-up to determine their residual strengths. The CFRP girder without fireproofing lost 59% of its design flexural capacity, while the one with fireproofing did not experience any reduction in flexural capacity. The results of the load testing and rating of each girder will be presented.

Post-fire Assessment of Reinforced and Prestressed Concrete Bridge Elements

Presented By: TZU-CHUN TSENG
Affiliation: Purdue University - West Lafayette
Description: Several truck fires have occurred in recent years involving bridges with reinforced and prestressed concrete components. If the fire burns for a significant period of time, bridge inspectors and engineers must determine if the exposure to elevated temperature has reduced the strength and serviceability of the concrete components. Little guidance is available, however, regarding correlating the results of field inspections with the actual condition of the reinforced/prestressed concrete elements. A research program is underway to develop rational guidance for inspectors and engineers to evaluate concrete bridge elements after a fire event and help them make informed decisions regarding the future status of the bridge. The research program includes tests on portions of a reinforced concrete deck acquired from a decommissioned highway bridge. In addition, nine pretensioned concrete beam specimens with varying levels of prestress were fabricated and tested. The specimens had cross-sectional dimensions of 8 in. by 8 in. and were designed to simulate the bottom flanges of common I-shaped prestressed concrete bridge girders. All specimens were subjected to elevated temperatures using radiation-based heaters. The concrete temperature profiles and the deformations of the specimens were measured using thermocouple trees and an optical motion capture system, respectively. Moreover, the stress variations in the strands due to thermal effects were captured by high-temperature strain gauges. The strands were later extracted and tested. Concrete samples were also cored and examined using various methods (DSC, SEM, and XRD) to correlate microstructure degradation (microcracking, dehydration of C-S-H, decomposition of calcium hydroxide, etc.) with the measured temperatures through the depth of the specimens.

Application of Concrete Spalling Mitigation

Presented By: Kevin Mueller
Affiliation: Thornton Tomasetti
Description: The American Society of Civil Engineers (ASCE) Standard 7-16 “Minimum Design Loads and Associated Criteria for Buildings and Other Structures” was recently published. It includes a new Appendix E, “Performance-Based Design Procedures for Fire Effects on Structures,” which provides an optional performance-based design procedure addressing structural integrity, fire load development, heat transfer, and structural response. As engineers in North America start to apply these procedures, the mitigation of concrete spalling will become a critical design consideration. The heat transfer and structural analysis of reinforced concrete elements is highly dependent on the thickness of cover during the fire exposure, which can be significantly damaged or even completely removed under a fire event if spalling mitigation is not considered during design. This presentation will address the current state of practice to mitigate concrete spalling under fire in North America. First, it will provide an exhaustive code review for North American structural concrete design under fire, including ACI, ASCE, NBC, NFPA, ASTM, and SFPE, with emphasis on how each document addresses spalling. Second, it will explore the structural, materials, and experimental testing applications towards evaluating and mitigating concrete spalling through mixture design optimization and materials consulting. Third, it will provide a proposed design procedure and approach that engineers can follow when designing new structures as well as retrofitting existing structures.

Investigating Wave Forces on Coastal Bridge Decks

Presented By: Guoji XU
Affiliation: University of Notre Dame
Description: Tsunamis and hurricanes induced waves are responsible for many coastal bridge failures, especially in the last decade. In this talk, the wave generation methods for various wave theories are introduced. Two bridge types, single bridge deck and twin bridge decks, are taken into account. Two wave-load mitigation methods, reducing the entrapped air and elevating the structures, are presented. A comprehensive understanding of the bridge deck-wave interaction can provide useful information for the stakeholders and decision makers to issue expedient orders, i.e., whether or not close the bridge, for the evacuation purpose in these extreme events.

Bridge Fragility Models for Spatial Accessibility Assessment in Areas Prone to Coastal Hazards

Presented By: Georgios Balomenos
Affiliation: McMaster University
Description: The transportation infrastructure is vital to ensure connectivity for supporting post event mitigation efforts in areas exposed to coastal hazards. So far, studies tend to focus only on road closures, neglecting structural damage on the infrastructure during these events, such as bridge deck uplift which was found to be a common failure mode in coastal areas exposed to hurricane induced storm surge and waves. This study provides a framework which takes into the structural damage of bridges and examines how the disruption of transportation networks during and after a hurricane can impact residents’ ability to access health services over time. The proposed framework combines developed fragility models for bridges with GIS-based spatial accessibility models, for two different bridge closure conditions along with roadway inundation. A study area is selected, located in the US Gulf Coast region, and accessibility analyses are conducted for two-time horizons. The results highlight the importance of fragility models in these types of analysis and indicate that spatial accessibility can be highly related bridge vulnerability alone. Sociodemographic indicators are also examined for the study region, in order to investigate which populations are most likely to suffer from lack of accessibility. In general, the proposed framework can assess post-hazard accessibility towards the resilience of coastal communities, and to shape decisions about future mitigation and planning efforts.

Investigating Wave Forces on Coastal Bridge Decks

Presented By: Guoji XU
Affiliation: University of Notre Dame

Upper Level Sponsors

Advance Ready Mix Concrete, Inc.
Anderson Concrete Corp.
Dugan and Meyers LLC
Euclid Chemical
Forta Corporation
Greater Miami Valley Chapter – ACI
Hilltop Companies
Irving Materials, Inc.
Indiana Chapter - ACI
Largo Concrete, Inc.
Lebanon Chapter – ACI
Lithko Contracting, LLC
Messer Construction Co.
Northern California & Western Nevada Chapter - ACI
PlanGrid - an Autodesk Company
Quebec and Eastern Ontario Chapter – ACI
RMD Kwikform
Ruttura & Sons
San Antonio Chapter – ACI
Terracon Consultants, Inc.
TWC Concrete Services, LLC
Webcor Builders
West Michigan Chapter – ACI