10.1 Steel Erection (Subpart R)
Key Takeaways
- Steel erection may not begin until the controlling contractor provides written notification that concrete in footings, piers, and walls has reached 75 percent of intended minimum compressive design strength or enough strength to carry erection loads.
- All columns must be anchored by a minimum of 4 anchor rods, and the anchor rod assembly must resist a 300-pound eccentric gravity load applied 18 inches from the outer face of the column.
- The general steel erection fall protection trigger is more than 15 feet; connectors and controlled decking zone workers are protected at more than two stories or 30 feet, whichever is less.
- A controlled decking zone may be no more than 90 feet wide and 90 feet deep from any leading edge, with unsecured decking never exceeding 3,000 square feet.
- A multiple lift ('Christmas tree') may hoist a maximum of five members, only beams and similar structural members, with a purpose-built rigging assembly and trained employees.
10.1 Steel Erection (Subpart R)
Core Principle: 29 CFR 1926 Subpart R (1926.750–761) is the 2001 rewrite of steel erection, and it is worth studying because so much of it is pre-work — conditions the controlling contractor must create and certify in writing before an erector is permitted to set the first piece. Steel erection also carries its own fall protection triggers that override the Subpart M 6-foot rule, which makes it a favourite for cross-standard exam questions.
Steel erection is a named elective topic in both the 10-hour and 30-hour construction outreach outlines, so an authorized trainer should be able to deliver at least 30 minutes on it competently.
1. Before the First Piece: Site Layout and Written Notifications (1926.752)
The 75 Percent Concrete Rule
A steel erection contractor shall not erect steel until it has received written notification that the concrete in the footings, piers, and walls, or the mortar in masonry piers and walls, has attained — on the basis of an appropriate ASTM standard test method of field-cured samples — either:
- 75 percent of the intended minimum compressive design strength; or
- sufficient strength to support the loads imposed during steel erection.
The controlling contractor must ensure the erector receives that written notification, along with written notice that any repairs, replacements, or modifications to the anchor bolts were performed in accordance with 1926.755(b).
Exam Trap: The notification is a written precondition running from the controlling contractor to the steel erector. A verbal assurance from the concrete sub does not satisfy 1926.752(a) or (b), and the erector has an independent duty under (b) not to start without it.
Site Layout Duties of the Controlling Contractor (1926.752(c))
The controlling contractor must provide and maintain:
- Adequate access roads into and through the site for safe delivery and movement of derricks, cranes, trucks, other equipment, and the material to be erected, with means and methods for pedestrian and vehicular control (this does not extend to roads outside the site); and
- A firm, properly graded, drained area, readily accessible to the work, with adequate space for the safe storage of materials and the safe operation of the erector's equipment.
Pre-Planning
The controlling contractor must also ensure that the steel erector is afforded a safe site layout and that the erection sequence has been planned. Where a site-specific erection plan is used in lieu of certain Subpart R provisions, Appendix A to Subpart R describes what such a plan should contain, and it must be prepared by a qualified person.
2. Column Anchorage and Stability (1926.755)
These numbers are among the most quotable in all of Part 1926.
| Requirement | Value |
|---|---|
| Minimum anchor rods (anchor bolts) per column | 4 |
| Design load the anchor rod assembly, column-to-base-plate weld, and column foundation must resist | a minimum eccentric gravity load of 300 pounds |
| Location at which that load is applied | 18 inches from the extreme outer face of the column, in each direction, at the top of the column shaft |
| Column setting surface | Level finished floors, pre-grouted leveling plates, leveling nuts, or shim packs adequate to transfer construction loads |
| Guying/bracing decision | All columns shall be evaluated by a competent person to determine whether guying or bracing is needed; if needed, it shall be installed |
Anchor rod modification (1926.755(b)): anchor rods shall not be repaired, replaced, or field-modified without the approval of the project structural engineer of record, and the controlling contractor must notify the erector in writing before erection begins if any such work was done.
3. Structural Steel Assembly (1926.754)
Three limits govern how far erection may outrun completion:
- Permanent floors: installed as erection progresses, with not more than eight stories between the erection floor and the uppermost permanent floor, except where structural integrity is maintained by design.
- Unfinished bolting or welding: at no time more than four floors or 48 feet, whichever is less, above the foundation or uppermost permanently secured floor, except where structural integrity is maintained by design.
- Fall protection below: a fully planked or decked floor or nets must be maintained within two stories or 30 feet, whichever is less, directly under any erection work being performed.
Shear connectors (1926.754(c)(1)): headed steel studs, steel bars, steel lugs, and similar devices shall not be attached to the top flanges of beams, joists, or beam attachments so that they project vertically from or horizontally across the top flange until after the metal decking or other walking/working surface has been installed. They are a deliberate tripping hazard control, and a classic citation on decks where the studs went on early.
4. Fall Protection in Steel Erection (1926.760)
This is the heart of the subpart and the most examined part of it. Subpart R replaces the Subpart M 6-foot trigger with its own scheme.
| Who | Trigger Height | Protection |
|---|---|---|
| Each employee engaged in a steel erection activity on a walking/working surface with an unprotected side or edge | more than 15 feet above a lower level | Guardrail systems, safety net systems, personal fall arrest systems, positioning device systems, or fall restraint systems |
| Connectors | fall hazards of more than two stories or 30 feet, whichever is less | Protected per (a)(1); and at heights over 15 and up to 30 feet, provided with a PFAS, positioning device, or fall restraint system and wearing the equipment necessary to be able to tie off, or provided other (a)(1) means |
| Employees in a controlled decking zone (CDZ) | fall hazards of more than two stories or 30 feet, whichever is less | CDZ rules below |
| All other construction work on the site (Subpart M) | 6 feet | Subpart M systems |
Perimeter safety cables (1926.760(a)(2)): on multi-story structures, perimeter safety cables must be installed at the final interior and exterior perimeters of the floors as soon as the metal decking has been installed. They must meet the guardrail criteria in 1926.502.
The Controlled Decking Zone (1926.760(c))
A CDZ may be established over 15 and up to 30 feet above a lower level, in the area where metal decking is initially being installed and forms the leading edge. Seven conditions apply:
- Employees working at the leading edge are protected from fall hazards of more than two stories or 30 feet, whichever is less.
- Access is limited to employees engaged in leading edge work.
- The CDZ boundaries are designated and clearly marked, no more than 90 feet wide and 90 feet deep from any leading edge, marked by control lines or the equivalent.
- Each employee in a CDZ must have completed CDZ training under 1926.761.
- Unsecured decking in a CDZ shall not exceed 3,000 square feet.
- Safety deck attachments are performed from the leading edge back to the control line, with at least two attachments for each metal decking panel.
- Final deck attachments and installation of shear connectors shall not be performed in the CDZ.
Custody of Fall Protection (1926.760(e))
Fall protection provided by the steel erector remains in a completed area for other trades only if the controlling contractor has directed the erector to leave it in place and has inspected and accepted control and responsibility for it before authorizing non-erectors to work there. Absent both, the erector may remove it.
5. Hoisting and Rigging (1926.753)
- Pre-shift inspection: a qualified rigger (a rigger who is also a qualified person) must inspect the rigging prior to each shift in accordance with 1926.251.
- Operator authority: the operator has the authority to stop and refuse to handle loads whenever there is any doubt as to safety.
- Personnel: the headache ball, hook, or load shall not be used to transport personnel; cranes may hoist employees on a personnel platform only under 1926.1431.
- Safety latches: latches on hooks shall not be deactivated or made inoperable except in the narrow circumstances listed in (c)(5).
- Working under loads: routes shall be pre-planned so that no employee is required to work directly under a suspended load except employees hooking or unhooking it or engaged in initial connection.
The Multiple Lift Rigging Procedure ("Christmas Treeing")
A multiple lift may be performed only if all of the following are met (1926.753(e)(1)):
- A multiple lift rigging assembly is used;
- A maximum of five members are hoisted per lift;
- Only beams and similar structural members are lifted;
- All employees engaged have been trained under 1926.761(c)(1); and
- No crane is used where such use is contrary to the manufacturer's specifications and limitations.
The rigging assembly components must be specifically designed and assembled with a maximum capacity for the total assembly and for each individual attachment point.
6. Training (1926.761)
Training must be provided by a qualified person and must cover the recognition and avoidance of hazards associated with the employee's work. Three specialized training categories carry named requirements:
- Multiple lift rigging procedure — for every employee engaged in one;
- Connector procedures — for connectors, covering the nature of the hazards and the establishment, access, proper installation techniques, and work practices for connecting; and
- Controlled decking zone procedures — for every employee working in a CDZ, covering the nature of the hazards and the establishment, access, proper installation techniques, and work practices for a CDZ.
A steel erector arrives on site and the concrete subcontractor's foreman states verbally that the footings 'are well past 75 percent by now.' Under 29 CFR 1926.752, may the erector begin setting columns?
An ironworker crew is installing metal decking at the leading edge of a floor 26 feet above the level below, working inside a designated controlled decking zone. Which set of limits applies to that zone under 29 CFR 1926.760(c)?
A crane operator is asked to perform a multiple lift, hoisting seven pieces of steel on a single rigging assembly including two steel joists and five beams. What does 29 CFR 1926.753(e) permit?