Detailing for Increased Breakout Capacity of Steel Anchor Rods in Concrete Podium Slabs (Recording)

Multi-story light-frame structures are often built atop concrete podiums, and in areas of high seismicity the overturning restraint system used to secure shear walls in these buildings can produce very high tension demands on the concrete anchorage components of these systems. While the loads can be high, podium slabs tend to be fairly shallow (14” or less), and the design resistance calculated according to code provisions often isn’t enough. While anchor reinforcement detailing is address in ACI318, the form it would need to take in slab situations is not addressed. Recognizing this, a small group of practicing engineers, funded by a SEAONC Special Projects Initiative and supported by Simpson Strong-Tie, began an ambitions investigation into how to provide detailing (anchor reinforcing) that increases the breakout resistance of concrete anchors in podium slabs. A discussion on the history, the testing and findings as well as the calculation, design and detail of anchor reinforcement in relatively thin concrete podium slabs used to help resist seismic and wind uplift forces for light frame construction.