Column anchoring and stability

All columns must be anchored with at least four anchor rods (anchor bolts). This is the plain requirement in 1926.755(a)(1).

• Use a minimum of four anchor rods per column; do not erect a column relying on fewer unless an approved alternative design is provided by the project structural engineer of record.

Each anchor rod (anchor bolt) assembly must be designed to resist a minimum eccentric gravity load of 300 pounds located 18 inches from the extreme outer face of the column in each direction at the top of the column shaft. See 1926.755(a)(2).

• The assembly includes the anchor rod, the column-to-base plate weld, and the column foundation as part of the resisting system.
• The requirement sets both the load magnitude (300 lb) and the eccentric location (18 in.) used to check stability.

The 300-pound eccentric gravity load is applied at the top of the column shaft, 18 inches from the extreme outer face of the column in each direction. This location and magnitude are specified in 1926.755(a)(2).

• Designers use that 18-inch lever arm to calculate the moment the anchor assembly must resist for both directions around the column.

Yes. The anchor rod assembly design must include the column-to-base plate weld and the column foundation as part of the assembly that resists the specified eccentric load, per 1926.755(a)(2).

• When performing design or checking stability, include the welds and foundation behavior because they affect the assembly's capacity to resist the 300-pound eccentric load.

Columns must be set on level finished floors, pre-grouted leveling plates, leveling nuts, or shim packs that are adequate to transfer the construction loads, as required by 1926.755(a)(3).

• Use leveling systems that provide a stable, bearing surface and prevent uneven load transfer during erection and subsequent construction loading.
• Avoid makeshift supports that cannot reliably transmit loads to the foundation or floor.

An adequate leveling device is one that provides stable, full bearing and can safely transfer the expected construction loads from the column to the supporting surface without excessive deformation or movement; this is the requirement in 1926.755(a)(3).

• Adequacy is judged by whether the device prevents uneven settlement or rotation under the loads during erection and construction.
• Typically a qualified designer or competent person confirms suitability based on load calculations, manufacturer guidance, and site conditions.

A competent person must evaluate all columns to determine whether guying or bracing is needed, and if it is needed it must be installed, as required by 1926.755(a)(4).

• The standard explicitly requires the evaluation by a competent person; that individual should have the training and experience to judge erection stability and recommend controls.
• If the competent person determines guying or bracing is necessary, those measures must be installed before or during erection as appropriate to protect workers and stability.

If a competent person determines guying or bracing is needed, it must be installed (i.e., you must install the required guying or bracing). This is stated in 1926.755(a)(4).

• Install bracing or guys promptly so columns are stable during erection and while subsequent work proceeds.
• Follow the competent person's instructions and any design details provided by the project structural engineer.

No. Anchor rods (anchor bolts) shall not be repaired, replaced, or field-modified without the approval of the project structural engineer of record, per 1926.755(b)(1).

• Any on-site changes to anchor rods require explicit approval from the project structural engineer of record before the work is done.
• This protects column stability and ensures the modified system still meets the required design capacity.

The project structural engineer of record must approve any repair, replacement, or field modification of anchor rods, as required by 1926.755(b)(1).

• Obtain written or documented approval from that engineer before performing the work so the modified anchor system meets stability and safety requirements.

Before erection of a column, the controlling contractor must provide written notification to the steel erector if there has been any repair, replacement, or modification of the anchor rods of that column, per 1926.755(b)(2).

• The notification must be in writing and occur prior to erection so the erector knows about changes that could affect column stability or erection procedures.
• Keep records of the notification as part of project documentation.

Yes. The general requirements in 1926.755(a) apply to all columns being erected; for example, every column must meet the minimum anchor and stability provisions in 1926.755(a).

• That includes the minimum four anchor rods, the eccentric load design requirement, proper leveling, and a competent-person evaluation for guying or bracing.

1926.755(a)(1) requires a minimum of four anchor rods, so using a different layout that reduces the number below four is not allowed unless an alternative is justified and approved by the project structural engineer of record (see 1926.755(a)(1) and 1926.755(b)(1)).

• Any deviation from the minimum requires approval from the project structural engineer of record and should be documented in writing before erection.

You should verify by design calculations or engineer review that the complete anchor rod assembly—including the anchor rod, the column-to-base plate weld, and the column foundation—resists the 300-pound eccentric load located 18 inches from the extreme outer face of the column, as required by 1926.755(a)(2).

• Have the project structural engineer of record perform or review those calculations.
• Include checks for both directions (the load is specified "in each direction") and consider combined loading conditions during construction.

No. Any repair, replacement, or field modification of anchor rods—such as welding, cutting, or changing bolt geometry—must be approved by the project structural engineer of record before it is performed, according to 1926.755(b)(1).

• Do not proceed with field modifications without documented approval to avoid undermining column stability and violating the standard.

The controlling contractor must provide written notification to the steel erector prior to the erection of the affected column if there has been any repair, replacement, or modification of that column's anchor rods, per 1926.755(b)(2).

• This written notice should include what work was done, who approved it (the project structural engineer of record), and any special erection instructions resulting from the modification.

The 18-inch offset specified in 1926.755(a)(2) establishes a consistent lever arm for design checks so anchor rod assemblies are evaluated for a realistic overturning moment during construction.

• Using that fixed eccentricity ensures designers and contractors assess resistance to moment in both directions and helps prevent unexpected instability during erection.

Columns must be set on level finished floors, pre-grouted leveling plates, leveling nuts, or shim packs that are adequate to transfer construction loads, according to 1926.755(a)(3). Temporary supports are acceptable only if they meet those criteria and reliably transfer loads; they must provide stable bearing comparable to the listed acceptable methods.

• Avoid ad hoc supports that do not provide full bearing or could shift during construction; a competent person or engineer should approve temporary arrangements.

When anchor rods are repaired, replaced, or modified, the approval from the project structural engineer of record and the written notification to the steel erector should be documented and retained, as implied by 1926.755(b)(1) and 1926.755(b)(2).

• Keep engineering approval records, descriptions of the modification work, and the controlling contractor's written notice to the erector in the project files for verification and inspection.