High early strength concrete (HESC) is a high performance concrete that can achieve structural quality within 24 to 72 hours of being poured, making it ideal for locations where minimal traffic disruption is crucial. Washington and nine other states have successfully used calcium sulfoaluminate (CSA) for bridge deck repair. CSA is a desirable option for HESC because of its ability to set within a short time window (as quickly as 15 minutes after placement) and to easily surpass a compressive strength of 3,000 psi in under three hours. However, while CSA has the potential to be successfully used for HESC bridge deck overlays, more data are needed to develop appropriate guidance and specifications for its use. The objective of this study is to develop an HESC mix design with CSA cement for bridge overlays. The researchers will identify the obstacles or impediments to successfully and reliably using HESC for bridge deck overlays and will develop standards, specifications, processes, and best practices for constructing HESC overlays in Washington. This will give WSDOT the means to reliably construct overlays to rehabilitate and protect bridges with lower construction costs and less travel disruption.

Principal Investigators:
Fred Aguayo, Construction Management, UW
Travis Thonstad, Civil and Environmental Engineering, UW

Sponsor: WSDOT
WSDOT Technical Monitor: Anthony Mizumori
WSDOT Project Manager: Mustafa Mohamedali
Scheduled completion: September 2025

Agencies that own transportation infrastructure such as bridges, dams, and marine terminals need validated, science-based tools to inform crucial decisions regarding the maintenance, repair, and operation of that infrastructure. This proof-of-technology project is evaluating the benefits, limitations, and tradeoffs that an agency can expect when using digital twin technologies for asset management. A digital twin is a virtual representation of an object or system designed to accurately reflect a physical object, including its functionality, features, and behavior. Real-time embedded, Internet-of-things (IoT) sensing technologies that feed a digital twin model have the potential to monitor conditions over time. This capability can lead to a database covering all seasons of the year, and thus a rich understanding of past and present operational conditions on which to base maintenance and repair decisions. For this project researchers are positioning sensors on the I-90 Homer M. Hadley Memorial Bridge between Mercer Island and Seattle, one of the most complex bridges in the world. Their analyses should provide insights into the realistic capabilities of digital twins and how the technology may be helpful to transportation agencies in stretching preservation dollars and staff resources.

Principal Investigators:
Bart Treece, Mobility Innovation Center, UW
Travis Thonstad, Civil and Environmental Engineering, UW

Sponsors:
WSDOT
FHWA Statewide Transportation Innovation Council (STIC)
Challenge Seattle

WSDOT Technical Monitor: Nick Rodda
WSDOT Project Manager: Mustafa Mohamedali
Scheduled completion: September 2025

Today’s girders are much longer and heavier than those that have been used in the past. This poses challenges to transportation agencies in handling, transporting, and erecting the girders, as under their own weight they can buckle laterally and fail.  Traditionally, analysis of this potential behavior has ignored torsional deformations because doing so greatly simplifies the calculations. However, although traditional models have so far proved adequate, today’s longer, heavier girders are challenging their assumptions. And with those girders, the potential consequences of ignoring torsional deformation could prove to be not only costly in terms of time and money but also unsafe. This project is seeking to improve the fundamental characterization of girder instability by developing new models that include torsional deformation and consider a broad range of material properties and concrete weights. Models will be developed to analyze both the lateral stability of uncracked girders and the role of cracking in reducing girder stiffness and thus increasing instability. The researchers will assist WSDOT in implementing the findings by providing the lateral stability criteria necessary to develop a set of new girder shapes that will take advantage of the materials that allow the use of longer spans.

Principal Investigators:
John Stanton, Civil and Environmental Engineering, UW
Richard Wiebe, Civil and Environmental Engineering, UW

Sponsor: WSDOT
WSDOT Technical Monitor: Geoff Swett
WSDOT Project Manager: Mustafa Mohamedali
Scheduled completion: March 2024

In 1991 WSDOT began a seismic retrofit program for state bridges that continues today. WSDOT’s primary method for retrofitting concrete bridge columns is steel jackets. The USGS recently released updated hazard maps that require structural design in Western Washington to plan for increased levels of seismicity, reflecting the potential for the Cascadia Subduction Zone (CSZ) to generate large magnitude, long duration earthquakes. The ability of WSDOT’s bridge columns retrofitted with steel jackets to resist this increased earthquake hazard level is not well understood, and questions remain regarding the level of damage that would be sustained in a CSZ earthquake. If the level of retrofit is not sufficient to prevent collapse, the millions of dollars expended by WSDOT on retrofit will not deliver the intended results. This project will characterize the expected performance, ductility capacity, and collapse probability of steel jacket retrofitted bridge columns in CSZ earthquakes and will develop a simple tool that WSDOT can use to assess whether a standard steel jacket retrofit is adequate to resist a design level earthquake for each bridge column in its inventory.

Project Investigators:
Christopher Motter, Civil and Environmental Engineering, WSU
Adam Phillips, Civil and Environmental Engineering, WSU

Sponsor: WSDOT
WSDOT Technical Monitor: Bijan Khaleghi
WSDOT Project Manager: Mustafa Mohamedali
Scheduled completion:  September 2021

The overall goal of the proposed research is to design, and prove experimentally, methods to seismically retrofit prestressed concrete hollow pile-columns used in bridges.  WSDOT maintains approximately 25 bridges that are supported on hollow precast, prestressed concrete pile-columns. Most were constructed in the 1960s. The seismic performance of these bridges is in now question because the hollow sections have been shown to have little flexural ductility, which may cause them to fail prematurely. This project will determine the flexural strength and deformation capacity of a typical as-built, hollow, precast, pre-tensioned pile-column before retrofitting. Researchers will then develop a retrofit method, including design procedures, for the potential plastic hinge at the cap beam connection, and they will develop implementation procedures for the retrofit method. In addition, this project will create a simple numerical modeling tool that will allow WSDOT to rank existing bridges according to the risk that they pose to help it prioritize bridge retrofitting.

Principal Investigators:
John Stanton, Civil and Environmental Engineering, UW
Paolo Calvi, Civil and Environmental Engineering, UW

Sponsor: WSDOT
WSDOT Technical Monitor: Bijan Khaleghi
WSDOT Project Manager: Doug Brodin
Scheduled completion: December 2019

The last official release of a steel version of the bridge rating software that WSDOT uses was Bridg97. That software offers WSDOT’s and FHWA’s standard rating systems, both based on Load Factor Rating (LFR). Unfortunately, it depends on software packages that have become obsolete. WSDOT has also adapted a concrete version of Bridg (last official release was Bridg10), whose updated interface is platform independent.  Steel Bridg shares large portions of the user interface with concrete Bridg, and so parallel development has been dedicated to porting the steel-­specific user interface into a new, platform-independent steel Bridg version, although it still has technical limitations related to WSDOT and FHWA standard rating, as well as graphics capabilities. This project is working to further upgrade the new steel Bridg by porting the load module and LRFR-specific extensions from the concrete Bridg to the improved steel Bridg software and otherwise utilizing the existing features of Bridg97.

Principal Investigator: Peter Mackenzie-Helnwein, Civil and Environmental Engineering, UW
Sponsor: WSDOT
WSDOT Technical Monitor: Mohamad Al-Salman
WSDOT Project Manager: Jon Peterson
Scheduled completion: June 2024