INSIDE/OUT ISSUE 65
SPRING
NEWSLETTER
APRIL 2017
Seismic Design Considerations for Accelerated Bridge Construction Technologies Lee Marsh connects the dots between seismic design principles and bridges built with Accelerated Bridge Construction (ABC) technologies. ABC technologies offer efficient methods for construction of new bridges or replacement of bridges throughout the United States. According to the Federal Highway Administration, U.S. departments of transportation that employ ABC technologies can often Lee Marsh replace bridges in very short time frames, depending on the type of bridge. Often, key components can be placed within 48 to 72 hours shaving much time off bridge construction efforts. Such short time frames are often achieved by constructing new bridge superstructures off site then transporting and securing the finished integrated assembly to its final location. ABC technologies can also be used for the substructure and foundations creating additional time savings in on-site construction. ABC technologies have been used by BergerABAM’s engineers for years. Prestressed concrete girders, precast columns, pile caps, and other bridge elements fabricated off site are, in fact, ABC technologies, even though such technologies have only recently become known as ABC. Although ABC is fast and efficient, safety is never compromised. In fact, the state-of-the-art ABC planning, design, and construction methods can often produce
safer bridges that are more durable and provide longer service lives compared to traditional bridges. Bridge safety considerations include proper load limits, quality construction, and protection from natural hazards, such as floods, high winds—including hurricanes and tornados —and earthquakes. Before applying ABC technologies to bridge design in any seismic region of the country— whether it be a high or low seismic region—a fundamental understanding of bridge seismic performance is paramount. In January, at the Transportation Research Board’s 96th Annual Meeting in Washington, DC, the president and chief executive officer of BergerABAM, Lee Marsh, participated in a workshop addressing seismic concerns of ABC substructures, along with design recommendations and field implementations for the most commonly used ABC details. While the overall goal of the workshop was to examine many of the performance, design, and behavioral issues of proposed energy dissipating (ED) elements used in ABC in seismic regions, Lee’s part of the workshop covered the fundamental principles of seismic design as they relate to ABC technology. Seismic design has three guiding principles that have been used for years in conventional construction but are also applicable to bridges built with ABC techniques. These principles were discussed in the workshop as described on the following page. (continued on page 2)
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