The standard specifies three distinct failure modes that the chair must resist:
Tightening a nut directly onto a thin column base plate can cause the plate to bend or "dish."
These are the plates that transfer the load from the top plate down to the vessel base. AISI formulas ensure these do not buckle under compression.
When designing and constructing large-scale industrial shells, silos, and flat-bottom tanks, structural integrity is paramount. Anchor bolts are required at the supports to secure the structure against wind, seismic activity, and operational loads. However, simply bolting a structure to a concrete foundation isn't always enough. Without proper load distribution, high localized stresses can damage the shell. aisi e 1 volume ii part vii anchor bolt chairs better
Two parallel vertical plates welded to both the tank shell and the top plate. They transfer the load from the top plate down into the tank shell.
The American Iron and Steel Institute (AISI) provides the ultimate playbook for steel design. When it comes to cold-formed steel and specialized structural components, their manuals are the gold standard.
This is where anchor bolt chairs come into play. Governing bodies and industry leaders like the American Iron and Steel Institute (AISI) provide rigorous guidelines to ensure these components are designed safely. Specifically, provides the foundational framework for designing these critical elements. The standard specifies three distinct failure modes that
Traditional, non-standardized design methods frequently overcompensate for uncertainty by mandating excessively thick top plates and massive gussets. AISI’s formulas optimize component geometry based on actual stress fields. By applying AISI Part VII, fabricators can safely utilize thinner plates and smaller weld sizes. Across a large-diameter storage tank requiring dozens of anchor chairs, this optimization translates directly into significant material cost savings and reduced structural weight. 4. Simplified Fabrication and Welding Guidelines
"Better" is not just about calculation; it is about execution.
By relying on the rigorous engineering frameworks established in , structural engineers ensure a design that is safe, compliant, and built to last. When it comes to the safety of industrial steel construction, adhering to these proven specifications is undeniably the better choice. How Can We Assist You Further? Anchor bolts are required at the supports to
AISI E-1 Volume II Part VII a widely recognized standard for the design of anchor bolt chairs
Vertical vessels, chimneys, and storage tanks experience severe overturning moments from environmental forces. Standard anchor bolts cannot always connect directly to a thin cylindrical shell without causing severe localized stresses. Anchor bolt chairs solve this problem by:
While standard anchor bolt chairs are designed to distribute local loads and minimize secondary bending in the shell, they can sometimes overstress light base rings or shells when spaced too closely. The AISI standard provides specific guidelines for this "better" alternative: The Continuous Top Ring Feature