Shallow Podium Anchors | May 14, 2021
Concrete podium structures have become an increasingly popular construction type for mixed-use buildings. Structural engineers are tasked with optimizing the thickness of concrete podium “transfer” slabs to provide as much floor-to-floor height as possible. In the Maryland area, post-tensioning is often utilized in podium slabs as it is popular with local contractors, structurally efficient, and an extremely effective means of minimizing the required thickness of the reinforced concrete. One challenge that results from thin podium slabs (especially those supporting 4 or more stories) is the need to resist anchoring forces at the ends of wood and light-gauge steel shear walls. Tension forces in shear wall anchors can easily surpass 100,000-pounds, and this often necessitates developing the full strength of the anchor rods embedded in the podium slab. Development of the full strength of the anchor rods requires significant length and hooks that cannot be accommodated in a thin concrete slab using conventional design calculations.
As a solution to this problem, a well-known structural connections fabricator, Simpson Strong-Tie, has developed a pre-engineered anchoring system capable of developing 120,000 psi high-strength steel rods in 10 to 14-inch-thick slabs. The “ATS Shallow Podium Anchor” system has been empirically validated by Strong-Tie at their Tye Gilb Laboratory in Stockton, California. Based on extensive destructive testing, Simpson Strong-Tie has developed and published tabulated wind and seismic design capacities for use by structural engineers. Innovations like the Shallow Podium Anchor serve as a reminder that it is critical to hire a structural engineering firm who has proven experience in optimizing structural floor thicknesses while also utilizing state-of-the-art technology to assist in satisfying prescribed building loads and other code requirements.
For more information on this anchoring technology, visit Simpson Strong-Tie’s structural engineering blog on anchor reinforcement for concrete podium slabs. https://seblog.strongtie.com/2015/06/anchor-reinforcement-for-concrete-podium-slabs/