This year’s Harry H. Edwards award winner is a shining example of how precast concrete can bring durability, performance, and efficiency to any project.
All of these benefits came together in the new Comstock graduate student housing at Stanford University, where the owners faced serious time and cost challenges. The project included replacing nine low-rise, two-story buildings that provided 79 beds, with four new buildings to accommodate more than five times as many students. The new structures also needed to include student meeting and social gathering spaces, laundry facilities, computer clusters, music practice rooms, game rooms, and other amenity spaces. The schedule was critical because it all had to be finished in time for the 2014 school year.
To meet the needs of the students in the short allotted schedule, the designers chose precast concrete solution rather than wood, says Mark Palmer of Clark Pacific, the precast concrete producer for the project. “With the speed of erection, the general contractor was able to deliver the student housing within one school year, getting students in quicker, and allowing the university to start bringing in revenue earlier.”
The buildings feature architecturally finished, structural precast concrete, unique vertically posttensioned, precast concrete walls for seismic resistance, and a first-ever in this region pre-topped plank system for the flooring. The general contractor chose a pretopped floor plank system because of its lower cost and schedule advantages compared with field-topped precast concrete, according to Palmer. The floor system consists of pre-topped, prestressed concrete planks; these planks span from exterior wall to exterior wall, over interior bearings walls, and result in a two-span plank. “The integration of the performance of a structural system with the finish of an architecturally clad precast concrete product saved time and money for everyone involved,” he says.
Once the existing dormitory housing structures were demolished, the new structures needed to be in place in a matter of months, which meant his team had to create up to 100 casts per week to match the fast-paced nature of the project. By prefabricating the components off-site, installation crews were able to keep the crowded campus clear of extra materials using just-in-time delivery, allowing cranes to lift the precast concrete pieces directly from the trucks and immediately install them. Palmer reports that up to 30 truckloads arrived daily, carrying wall panels and floor planks, during precast concrete erection. “Installation crews were able to set an entire floor of wall panels and floor planks above every three days, allowing other trades to follow quickly behind once the precast was installed,” he says.
A medium sandblast was used on all of the panels to match existing colors of the other buildings on the campus, while green and brown accent colors were used at the top of each building to add visual interest and contrast. Formliners were also used on the fourth-story panels to create a ribbed texture that wrapped around the upper floor of the dormitory buildings.
Along with meeting schedule and aesthetic goals, the precast concrete design delivered a more durable solution that will require minimal maintenance and meet seismic design requirements. “One of the most interesting aspects of this system is its ability to move like a hybrid moment frame,” Palmer says. “After a seismic event, the building will pull itself back to its original position.” Construction on the housing complex began in April 2013 and was completed in June 2014, well in advance of the academic year, Palmer says. “It was exciting to see how quickly a complete system like this could be built.”