Bond Performance of 1.125-inch-diameter Prestressing Strands


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CAIT project no.: CAIT-UTC-NC51

Fiscal Year: 2016/2017

Status: In Progress

Rutgers-CAIT Author(s): Marc Maguire, Ph.D., Andrew Sorensen, Ph.D.

External Author(s): Paul Aubee, Insteel Wire Products

Sponsor(s): FHWA - OST-R, Utah Department of Transportation

Principal investigator(s): Marc Maguire, Ph.D., PI • Andrew Sorensen, Ph.D., Co-PI

Performing organization(s): Utah State University

Managing organization: Rutgers CAIT

In cooperation with: Insteel Wire Products
Partner project manager: Paul Aubee, Engineering Manager

Supported by: USDOT OST-R

UTC, grant, or agreement no.: DTRT13-G-UTC28

Summary:

The public desires less disruption to highway services in addition to cheaper and more aesthetically pleasing structures. To meet these needs, engineers are continuously pushing the limits of current designs. One way to decrease the costs of an expensive structure is to limit the number of supports, provide longer span lengths, reduce the amount of materials and decrease construction time. In recent years, concrete bridges have benefited from larger diameter prestressing strands. Strands have gone from 0.5 in. to 0.6 in., mostly adopted as standard in the 1990s. In the mid 2000s research was underway to investigate larger strands and high strength strands (0.6 in. special, 0.7 in. and Grade 300). The largest available strands in the United States are 7-wire 0.7 in. diameter strands and are used sparingly in some early adoption states, despite several researchers finding that they can provide longer spans and more efficient structures with their use. The overarching goal of the proposed research is to investigate the use of 19-wire 1.125 in. diameter prestressing strand, purchased internationally, which has the potential to leapfrog several strand sizes. To accomplish this goal, the following more specific objectives have been identified:

1. Determine the level of cover required to ensure no splitting and bursting of 1.125 in. diameter strands.

2. Estimate the transfer length of 1.125 in. diameter prestressing strands.

3. Estimate the development length of 1.125 in. diameter prestressing strands.

4. Ensure the AASHTO LRFD specifications can predict the behavior of 1.125 in. diameter prestressing strand reinforced concrete members.