Aisi E 1 — Volume Ii Part Vii Anchor Bolt Chairs Better

: Required to be thick enough to prevent buckling, typically at least Welding : Standardizes minimum

The AISI standard provides specific formulas and guidelines for the following components:

Anchor bolts are rarely perfectly aligned, and eccentricity (the distance between the bolt's centerline and the shell) is a common challenge. AISI Part VII formulas specifically account for anchor bolt eccentricity, ensuring the chair can handle the twisting forces (moments) caused by this offset. Key Design Considerations under AISI E-1 Part VII

The distance between the anchor bolt and the shell is the eccentricity ( ). Minimizing this distance reduces the bending moment ( ) on the chair. aisi e 1 volume ii part vii anchor bolt chairs better

: Must be tall enough (typically between 6 and 33 inches) to distribute loads without overstressing the shell. Weld Strength

Before diving into the design standards, it helps to understand the anatomy of the component. An anchor bolt chair is a specialized steel device designed to support and align anchor bolts, transferring the tensile and shear loads from the bolts into the main structural shell or column. An anchor bolt chair typically consists of:

in diameter), base plates might be adequate to resist bending without additional supports. However, for larger shells, flat-bottom tanks, and tall silos, chairs are virtually mandatory. : Required to be thick enough to prevent

The AISI E1 standards emphasize the capacity of the anchorage to withstand tension and shear loads.

: When using a continuous ring, the standard requires checking for maximum stress in the circumferential direction. The ring is analyzed as if it were loaded with equally spaced concentrated loads equal to (where is bolt load, is eccentricity, and is chair height).

Pulling down on a bolt that sits inches away from a vertical shell creates an intense bending moment. If you simply weld a flat plate to the shell, that moment will cause local rotation, creating extreme localized secondary bending stress. The AISI E-1 Part VII design counteracts this by creating a rigid "box-like" chair structure. This architecture shifts localized tensile and compressive stresses into acceptable bounds along the vertical profile of the shell. Key Geometrical Parameters of AISI E-1 Part VII Minimizing this distance reduces the bending moment (

is a recognized industry standard for the design and analysis of anchor bolt chairs used to support shells, tanks, and columns. It provides a systematic procedure to ensure these attachments effectively distribute anchor bolt loads to the structure while minimizing secondary bending stresses. Why the AISI Design Is Considered "Better"

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While anchor chairs are excellent for discrete bolt locations, they should not be placed further than 10 feet apart. If the required bolt spacing is less than 2 feet 6 inches, the suggests a continuous top ring may be more efficient than individual chairs.