4.3 Concrete, Masonry & Steel Erection

Concrete, Masonry & Steel Erection

Candidates preparing for the OSHA 510 exam must master the safety standards for concrete and masonry construction (29 CFR 1926 Subpart Q) and steel erection (29 CFR 1926 Subpart R). Both fields involve heavy materials, elevated work, and rapid structural changes, creating severe struck-by hazards (falling tools, materials, structural collapse) and caught-in/between hazards (being crushed by formwork, collapsing masonry walls, or steel columns).

Concrete and Masonry Construction Standards (29 CFR 1926 Subpart Q)

Subpart Q covers the hazards associated with concrete work, reinforcing steel, formwork, precast concrete, lift-slab operations, and masonry walls.

Reinforcing Steel (Rebar) & Impalement Protection (1926.701(b))

One of the most frequent OSHA citations in concrete construction involves protruding reinforcing steel (rebar). All protruding rebar, onto or into which employees could fall, must be guarded to eliminate the hazard of impalement.

• Guarding Requirements: Rebar can be guarded using wood or plastic caps or troughs.
• Impalement-Rated Caps: Standard mushroom caps (which are round and made of thin plastic) are not designed to prevent impalement. They only protect against scratches and minor cuts. Protective caps must be ANSI-rated for impalement, which typically requires a steel reinforcement plate inside the plastic cap to withstand the impact of a falling worker. Alternatively, a continuous timber trough or 2x4 wood strip can be placed over a row of rebar.

Cast-in-Place Concrete, Formwork, and Equipment Safety

Formwork and shoring must be designed to safely support all loads, including the weight of the wet concrete, workers, and equipment.

• Formwork Design: Formwork must be capable of supporting all vertical and lateral loads. If shoring is used, it must be inspected by a competent person before, during, and after concrete placement.
• Concrete Buckets (1926.701(d)-(e)): Employees are not permitted to ride concrete buckets or work under suspended concrete buckets. The crane operator must avoid hoisting buckets over employees, and employees must stay out of the bucket's path (struck-by hazard).
• Post-Tensioning (1926.701(a)): No employee (except those essential to the tensioning operation) is permitted behind the jack during tensioning operations. If a tendon snaps under tension, it acts like a whip, creating a lethal struck-by hazard.
• Concrete Mixers, Pumps, and Tremies (1926.702):
  • Concrete mixers with 1 yard or larger loading skips must have a guardrail system on each side.
  • Concrete pump systems using discharge pipes must have safety chains or whip checks at pipe connections to prevent whipping if a joint fails.

Masonry Construction & Limited Access Zones (LAZ) (1926.706)

Masonry walls under construction are highly unstable until they are integrated into the building's permanent structure.

• Limited Access Zone (LAZ): A Limited Access Zone must be established whenever a masonry wall is under construction.
  • Width of the Zone: The width of the LAZ must be equal to the height of the wall to be reconstructed plus 4 feet, and it must run the entire length of the wall.
  • Location: The LAZ must be established on the side of the wall which will be unsupported (opposite the scaffold).
  • Access: Only employees actively engaged in constructing the wall are permitted in the LAZ. No other trades may enter.
  • Duration: The LAZ must remain in place until the wall is adequately braced to prevent collapse.
• Wall Bracing (1926.706(b)): All masonry walls over 8 feet in height must be adequately braced to prevent overturning and collapse. The bracing must remain in place until permanent lateral support is installed.

Steel Erection Standards (29 CFR 1926 Subpart R)

Subpart R governs the hoisting, rigging, layout, and assembly of structural steel members.

Structural Steel Assembly, Columns, and Connections

Structural steel erection requires strict sequence and mechanical safety controls to prevent premature collapse of the frame.

• Column Anchorage (1926.755(a)(1)): All columns must be anchored by a minimum of 4 anchor bolts to provide structural stability and prevent accidental overturning. Furthermore, these anchor bolts must not be repaired or replaced without the approval of the project structural engineer.
• Beams and Connections (1926.756): During structural steel assembly, beams must not be released from the hoisting line until they are secured with at least 2 bolts per connection, tightened to a wrench-tight condition.
• Double Connections: A double connection occurs when two girders share a column flange or beam web. To prevent one beam from falling when the second beam is connected, at least one bolt must remain in place, or a seating lug must be used, to support the first beam during the connection process.
• Multiple Member Lifting (MML) or "Christmas Treeing" (1926.753): Hoisting up to 5 individual structural steel members simultaneously is allowed, but only under strict conditions:
  • Members must be rigged at least 7 feet apart vertically.
  • Members must be set from bottom to top.
  • Total load must not exceed the capacity of the hoisting equipment.
  • Specialized rigging designed for MML must be used, and operators/riggers must be trained.

Steel Erection Fall Protection Rules (1926.760)

The fall protection rules in steel erection differ significantly from the general construction rules (which have a 6-foot trigger).

• General Steel Erection Workers: Each employee engaged in steel erection activity who is on a walking/working surface with an unprotected edge more than 15 feet above a lower level must be protected from falls.
• Connectors: A connector is an ironworker who receives and connects structural members. Connectors are permitted to work up to 30 feet (or 2 stories, whichever is less) before fall protection becomes mandatory. Between 15 and 30 feet, they must wear a personal fall arrest system (harness) and have a completed connector training, and the employer must provide an attachment point, but they are not strictly required to tie off if the employer can demonstrate that tying off increases the hazard. Above 30 feet, connectors must be tied off.
• Deckers: Workers installing metal decking are also permitted to work up to 30 feet (or 2 stories) before fall protection is required, provided they work inside a Controlled Decking Zone (CDZ).
• Controlled Decking Zones (CDZ) (1926.760(c)):
  • The CDZ must be marked with control lines and restricted to trained decking personnel.
  • The boundary must be marked with control lines consisting of flags or warning devices.
  • The CDZ cannot exceed 90 feet in width and 90 feet in depth from any leading edge.

Concrete, Masonry, and Steel Erection Reference Table