Category: Graduate Student Seminar Prestress Losses in UHPC and Hybrid Precast, Prestressed Bridge Girders

January 31, 2025 1:00 pm

In this quarterly IBT/ABC-UTC Research Seminar, Royce Floyd, Ph.D., P.E., S.E., Principal Investigator and Associate Professor of Civil Engineering and Environmental Science, University of Oklahoma; and Omar Yadak, Graduate Research Assistant, School of Civil Engineering and Environmental Science, University of Oklahoma, present work related to the Prestress Losses in UHPC and Hybrid Precast, Prestressed Bridge Girders.

presentation begins:  4:40
Q & A begins:  40:47

Presentation Documents:
Presentation Slides - Research Seminar January 2025 Presentation Slides
Intro & News Slides - Intro Slides January 2025 Research Seminar

Description:
Precast, prestressed concrete bridge girders are used extensively in conventional and accelerated bridge construction. End region behavior of prestressed concrete girders has been a significant concern warranting numerous studies over the years focused on stress limits, prestress transfer length, cracking caused by the prestress, and shear capacity. Ultra-high performance concrete (UHPC) is a relatively recent advancement in cementitious composite materials with mechanical and durability properties far exceeding those of conventional concrete. These improved mechanical properties have the potential to mitigate the impacts of high stresses in prestressed girder end regions and to provide greater overall girder capacity. However, little research has been conducted on the behavior of hybrid girders using UHPC in the end region or as a stay-in-place formwork shell. A total of five hybrid, four full UHPC, and two UHPC shell prestressed girder specimens were cast and instrumented to measure prestress losses over time. The results are being used to develop predictions for prestress loss behavior and recommendations for girder end region detailing.

Presenters:

Royce W. Floyd, Ph.D., P.E., S.E.
Associate Professor
School of Civil and Environmental Science
University of Oklahoma
Email: rfloyd@ou.edu

Royce Floyd is an Associate Professor in the School of Civil Engineering and Environmental Science at the University of Oklahoma and is an Associate Director of the Southern Plains Transportation Center. His current research focus is on extending the life of transportation infrastructure using innovative concrete materials, such as ultra-high performance concrete and calcium sulfoaluminate cement concrete. He has been PI or Co-PI on more than twenty projects sponsored by ODOT, SPTC, and ABC-UTC, including the first few field projects implementing ultra-high performance concrete in Oklahoma. He is a registered structural engineering in Oklahoma.

Omar Yadak
Ph.D. Student
School of Civil and Environmental Science
University of Oklahoma

 Omar Yadak is a Ph.D. student in structural engineering at the University of Oklahoma. He started his research journey as a senior undergraduate student when he assisted in field monitoring for the first implementation of UHPC for bridge deck panel joints and overlay in Oklahoma during replacement of the Eufaula Spillway Bridge. Omar has been part of several research projects related to UHPC. His master’s research focused on connections for composite columns using UHPC and his Ph.D. research will focus on hybrid conventional concrete/UHPC prestressed concrete beams.

Presentation Graphics:

Figure 1. Beam formwork showing insert to reduce the web thickness and vibrating wire strain gage


Figure 2.
UHPC end region cast simultaneously with conventional self-consolidating concrete


Figure 3.
Trial UHPC shell to evaluate bond between shell and infill concrete 


Figure 4
.  Failure of trial UHPC shell specimen showing no debonding between the materials