Two sturdy "legs" that transfer the bolt's massive pulling force into the tank wall.
In the architecture of light steel framing, the connection between a cold-formed steel (CFS) column and its concrete foundation is a nexus of complex forces. While the column efficiently transfers axial and lateral loads down its slender web, the anchor bolt must translate these forces into the mass of the footing. This interface, however, is not a simple meeting of steel and concrete; it is a zone of stress concentration, eccentricity, and potential failure. Recognizing this critical juncture, the American Iron and Steel Institute’s Standard for Cold-Formed Steel Framing – Design (AISI E 1) dedicates to a seemingly humble yet structurally vital component: the anchor bolt chair .
A thick steel plate with a hole for the anchor bolt to pass through. aisi e 1- volume ii- part vii anchor bolt chairs
The distance from the center of the anchor bolt hole to the edge of the seat plate must comply with AISI S100 (the main specification). For a chair under , the minimum edge distance is 2x the bolt diameter. For a typical 5/8” anchor bolt, this means the hole cannot be within 1.25 inches of the plate edge. This prevents the nut from tearing out the side of the chair.
comes in. Instead of a direct connection, engineers design a "chair"—a rigid steel assembly welded to the outside of the tank's wall. It consists of: Two sturdy "legs" that transfer the bolt's massive
The use of anchor bolt chairs provides several benefits, including:
: Must be sufficient to distribute the load without overstressing the shell. : Generally 6 inches; however, if the bottom plate is inch, a minimum of 12 inches is required. : Usually recommended not to exceed (top plate width) or approximately 33 inches. Top Plate Width ( This interface, however, is not a simple meeting
The American Iron and Steel Institute (AISI) is a leading organization that develops standards and guidelines for the steel industry. One of its most important publications is the AISI E 1, which provides specifications for the design and installation of cold-formed steel framing members. In this article, we will focus on Volume II- Part VII of the AISI E 1, which deals with anchor bolt chairs.