Keauhou Lane, a six-story mixed-use precast concrete building in Honolulu, is the first LEED- certified affordable rental mixed-use project delivered in the state of Hawaii.
be replaced. Engineer of record KPFF Consulting Engineers, Seattle, selected a single-span precast concrete spliced girder bridge as the preferred solution to address the client’s specific project goals for span, construction time line, and future maintenance. Precast spliced girders allowed designers to extend the span range to eliminate costly inter- mediate piers on the steep ravine and avoid impacting environmentally sensitive areas. The new two-lane single-span bridge is 32 feet wide and 309 feet long, comprised of a single post-tensioned 240-foot-long span and a 69-foot earth-filled approach. It is framed by five girder lines, each consisting of three precast, pretensioned segments erected on false work and post-tensioned together. The precast concrete pro- ducer was Concrete Technology Corp., Tacoma, Wash. For the Non-Highway Bridge (pedestrian, bicycle, railroad, etc.) cat- egory, the Aerial Guideway for the Dulles Corridor Metrorail in Hern- don, Va., received top honors. The Dulles Corridor Metrorail Project, Phase 2, includes a station at Dulles International Airport and an aerial guideway. Six track miles of aerial guideway pass through the airport, over wetlands to a maintenance yard, and connect to the western sec- tion of at-grade rail. Prestressed concrete girders in a chorded con- figuration worked well with the spans of up to 150 feet on the curved alignment. The girders incorporated draped prestressing strands with flared spacing at the ends. Florida wide-flange I-beam sections with four different depths were used to minimize the structure depth. Flex- ibility of the precast concrete elements also accommodated various
challenging elements, including track cross-overs and turnouts, as well as features for power and control systems. The ability to adjust the girder depth also allowed the designers to “tune” the structure to meet the vibration requirements for rider comfort, according to engineer of record, Parsons, Baltimore. The precast concrete producer was Coastal Precast Systems, Chesapeake, Va. The Peter Courtney Minto Island Bicycle & Pedestrian Bridge in Sa- lem, Ore., deemed the best Special Solution, connects 1,300 acres of riverfront parks and trails. The bridge had to clear the 100-year flood elevation, meet existing path grades with a limited approach, accom- modate grade limits for the Americans with Disabilities Act (ADA), and cross over an existing park path while providing adequate head room for pedestrians — all while accommodating a “no-rise” criterion for the 100-year flood elevation upstream of the bridge because the project is located within a FEMA floodway. The overall configuration is a five-span bridge, with a main span tied-arch of 304.5 feet at the springline chord, and thin cast-in-place, post-tensioned haunched slab approach spans. The main span features a pair of tied arches to support a precast panel stress-ribbon deck. The precast concrete producer was Knife River Prestress, Harrisburg, Ore.; the engineer of record was OBEC Consulting Engineers, Salem, Ore. Special projects Keauhou Lane, a six-story mixed-use precast concrete building in Ho-
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csengineermag.com
april 2018
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