A Mat Foundation at 101 PolkSep 24 2014 · 0 comments · NISHKIAN MENNINGER, Residential ·0
On Wednesday, August 30th, the concrete foundation of 101 Polk was poured. The foundation was the first structural element constructed at the future 13 story residential building located at a central San Francisco location of 101 Polk St. Located just one block away from City Hall, as well as the recently renovated tower at 100 Van Ness, the building continues the revival of the Civic Center area. The project is funded by The Emerald Fund, designed by Solomon Cordwell Buenz architects, and engineered by Nishkian Menninger.
Like many of the surrounding structures, 101 Polk is to be supported on a mat foundation. Mat foundations are essentially very thick floors that act rigidly in order to spread out the gravity and seismic loads on the building. With this type of foundation, large structures can be built directly on soft soil without the need for piles or other deep, costly foundations. While some mats can be as thick as 12 feet, for a project of this size, a three foot deep mat was selected.
After weeks of preparation, excavation, and placing rebar, the mat foundation was ready for concrete. Due to the high traffic location at Polk St. and Hayes St., and the number of concrete trucks that would be required to deliver a constant stream of concrete, the pour was scheduled to begin at 11 PM. Over a span of seven hours, over 150 concrete trucks arrived on site carrying a total of 1550 cubic yards of concrete. Using an app for concrete delivery (that’s right, there’s an app for that), trucks can be tracked as they leave the concrete yard and arrive on site. A notification can even be sent to the site superintendant when a truck arrives. Using this technology, a steady stream of trucks brought concrete to the site at an average rate of 250 cubic yards an hour.
At the end of the pour, only 8 cubic yards of concrete were left over. That’s just 0.5% of the total concrete order. Hats off to Pacific Structures for getting this project off to a great start!