{"id":7402,"date":"2015-03-03T17:01:58","date_gmt":"2015-03-03T22:01:58","guid":{"rendered":"http:\/\/www.constructionspecifier.com\/?p=7402"},"modified":"2016-12-22T14:33:39","modified_gmt":"2016-12-22T19:33:39","slug":"using-uhpc-to-improve-box-beam-bridge-performance","status":"publish","type":"post","link":"https:\/\/www.constructionspecifier.com\/using-uhpc-to-improve-box-beam-bridge-performance\/","title":{"rendered":"Using UHPC to improve box-beam bridge performance"},"content":{"rendered":"
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Pouring ultra-high-performance concrete (UHPC) for longitudinal joints\u2014the material could offer new benefits in box-beam bridge design and construction.<\/span> Images courtesy Ohio University\u2019s Russ College of Engineering and Technology<\/em><\/figcaption><\/figure>\n

by Eric Steinberg, PhD, PE
\n<\/strong>Out of the many types of bridges used across the country, adjacent prestressed, concrete box-beams have become popular for short and medium spans. Since these bridges are cost-effective, fast to construct, and easy to design, they are preferred by many state and local agencies. Currently used in about two-thirds of the country, many of these bridges are now approaching the end of their life span.<\/p>\n

Despite the widespread use and preference of these box-beam bridges, there are still some disadvantages associated with durability and effectiveness. As part of a recent project<\/a> with a team of students and colleagues, this author tested a box-beam bridge to failure in order to gauge behavior and overall capacity.<\/p>\n

This project prompted a major understanding in the way box-beam bridges perform. It showed the bridges perform well under stress, but the longitudinal bridge joints are susceptible to cracking and leakage, leading to accelerated corrosion, and reduced load transfer. The research also demonstrated complex behavior in the box-beam bridges due to thermal cycles, craftsmanship, and loading.<\/p>\n

While box-beam bridges have clear advantages, it is important to find ways to ensure they have a longer lifespan and handle the issues related to the longitudinal bridge joints. Right now, these bridges last about 30 years (depending on various factors), but if this time frame can be expanded, then owners will save on long-term infrastructure replacement costs. One solution this author is currently examining at Ohio University\u2019s Russ College of Engineering and Technology<\/a> is a new use of ultra-high-performance concrete (UHPC) in box-beam bridge design and construction.<\/p>\n

UHPC is an effective concrete material with superior properties to typical concretes and grouts, because it has a compressive strength greater than 150 kPa (22 psi) and a tensile strength in the range of 7 MPa (1 ksi). Also, the steel fibers allow for ductile behavior. According to the Federal Highway Administration (FHA)<\/a>:<\/p>\n

The mechanical and durability properties of UHPC make it an ideal candidate for use in developing new solutions to pressing concerns about highway infrastructure deterioration, repair, and replacement.<\/span><\/p>\n

This author first became involved with the material in September 2002 during a research trip to Paris, France, where it had been developed and was being used. There are currently 28 UHPC bridges<\/a> in the United States and 26 in Canada. UHPC is expected to be specified for more projects, and there are numerous signs of the material\u2019s rising importance in civil engineering. In November 2015, for example, the 1st<\/sup> International Interactive Symposium on Ultra-high-performance Concrete<\/a> will take place at the University of Connecticut. (This author is part of the organizing committee.)<\/p>\n

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Installation of instrumentation and wiring for the monitoring described in this article.<\/span><\/figcaption><\/figure>\n

Overall, UHPC is an expensive material, and full bridges made out of this type of concrete will significantly increase construction and design costs. The breakdown<\/a> is as follows:<\/p>\n