Candlestick Park was built in 1960 and has been the home of the San Francisco 49ers NFL team since 1971. “The Stick” was originally built as a baseball stadium for the then New York Giants baseball team to convince them move to San Francisco. Due to the wide spread popularity of the “Niners” football franchise, a new stand alone stadium in Santa Clara was approved and a groundbreaking ceremony was held in April of 2012. The project has a very demanding schedule that requires engineers and contractors to employ many methods to speed the construction phasing due to the fact that the new stadium is scheduled to open for the 2014 NFL season. View the 49er’s blog where you can see aerial photo gallery of the new stadium.
The open air football stadium employs thousands of stepped/ pre-cast concrete panels that will serve as the foundation for the fan seating areas. These pre-cast structures are steel reinforced and manufactured off site to reduce the forming cost/time on site and increase the consistency of the “skin on the bones” of the steel structure. These stair stepped panels were installed in late 2012 after a record breaking steel erection timeframe of the super structure. As part of the overall seating and viewing area plan, hundreds of flat platforms were included in the design to accommodate ADA ramps, wheelchairs, TV cameras and various other uses. Engineers with HNTB, one of the world’s foremost firms specified the use of Expanded Polystyrene (EPS) Geofoam to constitute the structural void fill to support the ramps and platforms. They chose EPS Geofoam due to its’ extreme low density and high bearing capacity to support the concrete topping slabs. By using an ultra-lightweight soil replacing fill material, EPS Geofoam significantly reduced dead and lateral loads on the pre-cast panels by adding elevation and slope without a lot of weight.
Conco Company of Concord, CA worked as a sub-contractor to Turner and Devcon Construction, the prime contractors to furnish and install the Geofoam as part of their large concrete package. Conco workers installed 3,500 cubic feet of EPS39 and 25,000 cubic feet of EPS15 for various ramps and platforms throughout the new stadium. The lightweight fill was provided by Insulfoam of Dixon, CA along with electric hot wire tool kits to allow workers to cleanly and easily fabricate the blocks on the jobsite. The single largest benefit to concrete contractors when using Geofoam is the ability of the material to constitute half of the form and the fill simultaneously which completely eliminates the concept of a two pour operation.