Steel Erection » Structural Stability

Structural steel assembly [29 CFR 1926.754]

Structural Steel Assembly

Since structural collapse is second only to falls as a cause of fatalities in this industry, stability is essential to the successful erection of any steel structure, including single- story, multi-story, bridges, etc. This section of the standard outlines the work practices that will prevent collapse due to lack of stability. In addition, it addresses slipping/tripping hazards and certain kinds of fall hazards encountered when working on steel structures.

Structural stability must be maintained at all times during the steel erection process. [29 CFR 1926.754(a)]

Safety Net
  • Permanent floors must be installed as the erection of structural members progresses, with no more than eight stories between the erection floor and the upper-most permanent floor. [29 CFR 1926.754(b)(1)]
  • Unfinished bolting or welding above the foundation (or the uppermost secured floor) is not permitted to exceed the lesser of [29 CFR 1926.754(b)(2)]:
    • Four floors
    • 48 feet (14.6 m)
  • Exceptions are allowed where structural integrity is accounted for in the design.
  • Safety nets or a fully planked or decked floor must be maintained directly under any erection work being performed, within the lesser of [29 CFR 1926.754(b)(3)]:
    • Two stories
    • 30 feet (9.1 m)
  • To prevent tripping hazards, the following components must not be attached so as to project from the top flanges of beams, joists, or beam attachments until after the metal decking, or other walking/working surface, has been installed [29 CFR 1926.754(c)(1)]:
    • Shear connectors (such as headed steel studs, steel bars, or steel lugs)
    • Reinforcing bars
    • Deformed anchors
    • Threaded studs
    • Exception: These may be factory installed if all workers, including connectors and deckers, use fall protection at all times. [CPL2-1.34, Q&A 25]
  • Sheer Connector
    When shear connectors are used in construction of composite floors, roofs and bridge decks, they must be laid out and installed after the metal decking has been installed, so the metal decking serves as a working platform. [29 CFR 1926.754(c)(1)]
  • Shear connectors may not be installed from within a controlled decking zone (CDZ). [29 CFR 1926.760(c)(7)]
  • Workers will not be permitted to walk the top surface of any structural steel member installed after July 18, 2006 that has been coated with paint or similar material, unless all of the following are met:
    • The coating has achieved a minimum average slip resistance of .50 in laboratory tests.
    • The tests were based on the appropriate ASTM standard test method and conducted by a qualified laboratory (Appendix B to this subpart references appropriate ASTM standard test methods).
    • Documentation of the test results is available at the site and to the steel erector.
  • When deemed necessary by a competent person, plumbing-up equipment must be installed during the steel erection process to ensure the stability of the structure. [29 CFR 1926.754(d)(1)]
  • Plumbing-Up
    When plumbing-up equipment is used, it must be in place and properly installed before the structure is loaded with construction material such as loads of joists, bundles of decking, or bundles of bridging. [29 CFR 1926.754(d)(2)]
  • Plumbing-up equipment may be removed only with the approval of a competent person. [29 CFR 1926.754(d)(3)]

Hoisting, Landing, and Placing of Metal Decking Bundles:

  • Bundle packaging and strapping may not be used for hoisting unless specifically designed for that purpose. [29 CFR 1926.754(e)(1)(i)]
  • If loose items such as dunnage, flashing, or other materials are placed on top of metal decking bundles intended to be hoisted, they must be secured to the bundles. [29 CFR 1926.754(e)(1)(ii)]
  • When bundles of metal decking are landed on joists, all bridging must be installed and anchored, and all joist-bearing ends attached. (See Open web steel joists for exceptions.) [29 CFR 1926.754(e)(1)(iii)]
  • Metal decking bundles must be landed on framing members so that enough support is provided to allow the bundles to be unbanded without dislodging the bundles from the supports. [29 CFR 1926.754(e)(1)(iv)]
  • At the end of the shift or when environmental or jobsite conditions require, metal decking must be secured against displacement. [29 CFR 1926.754(e)(1)(v)]

Roof and Floor Holes and Openings:

  • Metal decking at roof and floor holes and openings must be installed as follows:
    • Framed metal deck openings must have structural members turned down to allow continuous deck installation, except where prevented by structural design constraints or constructability. [29 CFR 1926.754(e)(2)(i)]
    • Openings such as roof and floor holes must be decked over.
    • Where large size, configuration, or other structural constraints do not allow openings to be decked over (e.g. elevator shafts, stair wells, etc.), employees must be protected in accordance with the fall protection provisions of this standard. [29 CFR 1926.754(e)(2)(ii)]
  • When metal decking holes and openings are cut, they must [29 CFR 1926.754(e)(2)(iii)]:
    • Immediately and permanently be filled with the intended equipment or structure.
    • Or immediately be covered.

Covering Roof and Floor Openings:

  • Covers for roof and floor openings shall be capable of supporting, without failure, twice the weight of the employees, equipment, and materials that may be imposed on them at any one time. [29 CFR 1926.754(e)(3)(i)]
  • All covers must be:
    • Secured when installed to prevent accidental displacement by the wind, equipment or employees. [29 CFR 1926.754(e)(3)(ii)]
    • Painted with high-visibility paint, or
    • Marked with the word "HOLE" or "COVER" to provide warning of the hazard. [29 CFR 1926.754(e)(3)(iii)]
  • Installed smoke dome or skylight fixtures are not considered covers, unless they meet the appropriate strength requirements. [29 CFR 1926.754(e)(3)(iv)]
  • Where planks or metal decking around columns do not fit tightly, wire mesh, exterior plywood, or equivalent material must be installed, and must be of sufficient strength to:

Installation of Metal Decking:


Derrick Floors:

  • To support the intended floor loading, a derrick floor must be fully decked and/or planked, and the steel member connections completed. [29 CFR 1926.754(e)(6)(i)]
  • Temporary loads placed on a derrick floor must be distributed over the underlying support members so as to prevent local overloading of the deck material. [29 CFR 1926.754(e)(6)(ii)]

Column anchorage [29 CFR 1926.755]


This section addresses the hazards associated with column stability and, specifically, the proper use of anchor rods (anchor bolts) to ensure column stability. Inadequate anchor rod/bolt installation has been identified as a primary contributing factor to structural collapses.

  • All columns must be anchored by a minimum of 4 anchor rods (anchor bolts). [29 CFR 1926.755(a)(1)]
  • Each column anchor rod (anchor bolt) assembly, including the column-to-base plate weld and the column foundation, must be designed to [29 CFR 1926.755(a)(2)]:
    • 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.
  • Columns must be set on elements that adequately transfer the construction loads [29 CFR 1926.755(a)(3)]:
    • Level finished floors
    • Pre-grouted leveling plates
    • Leveling nuts
    • Shim packs
  • All columns must be evaluated by a competent person to determine whether guying or bracing is needed; if guying or bracing is needed, it must be installed. [29 CFR 1926.755(a)(4)]
  • Approval by the project structural engineer of record is required before anchor rods (anchor bolts) can be [29 CFR 1926.755(b)(1)]:
    • Repaired
    • Replaced
    • Field-modified
  • Before the erection of a column, the controlling contractor must provide written notification to the steel erector if there has been any [29 CFR 1926.755(b)(2)]:
    • Repair
    • Replacement
    • Modification of the anchor rods of that column

Beams and columns [29 CFR 1926.756]

Beams and Columns

Inappropriate or inadequate connections of beams and columns is hazardous and can lead to collapses and worker fatalities. This section sets forth performance and specification requirements for connecting beams and columns, in order to minimize the hazard of structural collapse during the early stages of the steel erection process.

  • During the final placing of solid web structural members, the load must not be released from the hoisting line until [29 CFR 1926.756(a)(1)]:
    • The members are secured with at least two bolts per connection, of the same size and strength as shown in the erection drawings.
    • These bolts are drawn up wrench-tight.
    • The equivalent, as specified by the project structural engineer of record, except as specified in 29 CFR 1926.756(b) of this section.
  • A competent person must determine if more than two bolts are necessary to ensure the stability of cantilevered members if additional bolts are needed, they must be installed. [29 CFR 1926.756(a)(2)]
  • Solid web structural members used as diagonal bracing must be secured by [29 CFR 1926.756(b)]:
    • At least one bolt per connection drawn up wrench-tight.
    • The equivalent, as specified by the project structural engineer of record.
  • When two structural members on opposite sides of a column web, or a beam web over a column, are connected sharing common connection holes:
    • At least one bolt with its wrench-tight nut must remain connected to the first member; unless
    • A shop-attached, or field-attached seat or equivalent connection device is supplied with the member in order to (See Appendix H to this subpart for examples of equivalent connection devices.) [29 CFR 1926.756(c)(1)]:
      • Secure the first member.
      • Prevent the column from being displaced.
  • If a seat or equivalent device is used:
    • The seat (or device) must be designed to support the load during the double connection process.
    • Before the nuts on the shared bolts are removed to make the double connection, it must be adequately bolted or welded to both [29 CFR 1926.756(c)(2)]:
      • A supporting member
      • The first member

Each column splice 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.
  • Located at the top of the column shaft. [29 CFR 1926.756(d)]

Perimeter columns must not be erected unless:

  • They extend a minimum of 48 inches above the finished floor, to permit installation of perimeter safety cables prior to erection of the next story. [29 CFR 1926.756(e)(1)]
  • They have two sets of holes, or other devices that:
    • Are 42-45 inches above the finished floor, and also at the midpoint between the finished floor and the top cable.
    • Permit installation of perimeter safety cables as required by 29 CFR 1926.760(a)(2). [29 CFR 1926.756(e)(2)]

EXCEPTION: Where constructability does not allow, the above requirements can be waived. (See Appendix F to this Subpart.)

Open web steel joists [29 CFR 1926.757]

Open web steel joists

Some of the most serious risks facing the ironworker are encountered during the erection of open web steel joists, particularly landing loads on unbridged joists and improperly placing loads on joists. Based on a recent analysis of OSHA data, more than half of ironworker fatalities due to collapse are related to the erection of steel joists.

  • Where steel joists are used and columns are not framed in at least two directions with solid web structural steel members, the columns must be made laterally stable during erection by field-bolting the steel joist at the column. (See exception below) [29 CFR 1926.757(a)(1)]
  • When installing the stabilizing joist:
  • A vertical stabilizer plate for steel joists must be provided on each column, which must:
    • Be at least 6 inches by 6 inches.
    • Extend at least 3 inches below the bottom chord of the joist.
    • Have a 1316-inch hole to provide an attachment point for guying or plumbing cables. [29 CFR 1926.757(a)(1)(i)]
  • The bottom chords must be stabilized to prevent rotation during erection. [29 CFR 1926.757(a)(1)(ii)]
  • Hoist Cable
    Hoisting cables must not be released until:
    • The seat at each end of the steel joist is field-bolted.
    • Each end of the bottom chord is restrained by the column stabilizer plate. [29 CFR 1926.757(a)(1)(iii)]
  • EXCEPTION: Where constructability does not allow a steel joist to be installed at the column:
  • Hoisting cables must not be released until the seat at each end of the steel joist is field-bolted and the joist is stabilized. [29 CFR 1926.757(a)(2)(ii)]
  • Where steel joists at or near columns span 60 feet or less:
    • The joist must be designed with sufficient strength to allow one employee to release the hoisting cable without the need for erection bridging. [29 CFR 1926.757(a)(3)]
    • Alternatively, procedures described in the Compliance Directive may be used instead until July 18, 2003. [CPL 2-1.34, Q&A 32]
  • Where steel joists at or near columns span more than 60 feet:
    • The joists need to be set in tandem with all bridging installed. [29 CFR 1926.757(a)(4)]
    • An alternative method of erection may be used, which [29 CFR 1926.757(a)(4)]:
      • Provides equivalent stability to the steel joist.
      • Is designed by a qualified person.
      • Is included in the site-specific erection plan.
  • A steel joist or steel joist girder must not be placed on any support structure that is not stabilized. [29 CFR 1926.757(a)(5)]
  • When steel joists are landed on a structure, they must be secured to prevent unintentional displacement prior to installation. [29 CFR 1926.757(a)(6)]
  • Any modification that affects the strength of a steel joist or steel joist girder must be made with the approval of the project structural engineer of record. [29 CFR 1926.757(a)(7)]
  • When connecting individual steel joists to steel structures in bays 40 feet or longer (see exception below):
  • Steel joists and steel joist girders must not be used as anchorage points for a fall-arrest system unless written approval to do so is obtained from a qualified person. [29 CFR 1926.757(a)(9)]
  • A bridging terminus point must be established before bridging is installed. [29 CFR 1926.757(a)(10)]
  • Each end of "K" series steel joists must be finally attached to the support structure with a minimum of [29 CFR 1926.757(b)(1)]:
    • Two ⅛-inch fillet welds 1 inch long
    • Two ½-inch bolts
    • Or an equivalent connection
  • Each end of "LH" and "DLH" series steel joists and steel joist girders must be finally attached to the support structure with a minimum of [29 CFR 1926.757(b)(2)]:
    • Two ¼-inch fillet welds 2 inches long
    • Two ¾-inch bolts
    • Or an equivalent connection
  • Except for panelized joists, each steel joist must be attached to the support structure, with at least one end on both sides of the seat [29 CFR 1926.757(b)(3)]:
    • Immediately upon placement in the final erection position.
    • Before additional joists are placed.
  • Panels that have been pre-assembled from steel joists must be attached with bridging to the structure at each corner before the hoisting cables are released. [29 CFR 1926.757(b)(4)]
  • Where the span of the steel joist is equal to or greater than the span shown in Tables A and B, the following applies:
    • A row of bolted diagonal erection bridging must be installed near the mid-span of the steel joist. [29 CFR 1926.757(d)(1)(i)]
    • Hoisting cables must not be released until this bolted diagonal erection bridging is installed and anchored. [29 CFR 1926.757(d)(1)(ii)]
    • No more than one employee is allowed on these spans until all other bridging is installed and anchored. [29 CFR 1926.757(d)(1)(iii)]
  • Where the span of the steel joist is 60 feet through 100 feet, the following applies:
    • All rows of bridging must be bolted diagonal bridging. [29 CFR 1926.757(d)(2)(i)]
    • Two rows of bolted diagonal erection bridging must be installed near the third points of the steel joist (e.g. ⅓ joist-length) from each end. [29 CFR 1926.757(d)(2)(ii)]
    • Hoisting cables must not be released until this bolted diagonal erection bridging is installed and anchored. [29 CFR 1926.757(d)(2)(iii)]
    • No more than two employees are allowed on these spans until all other bridging is installed and anchored. [29 CFR 1926.757(d)(2)(iv)]
  • Where the span of the steel joist is 100 feet through 144 feet, the following applies:
  • For steel members spanning over 144 feet, the erection methods used must be in accordance with 29 CFR 1926.756. [29 CFR 1926.757(d)(4)]
  • Where any steel joist that requires bridging is a bottom chord bearing joist [29 CFR 1926.757(d)(5)]:
    • A row of bolted diagonal bridging must be provided near the supports.
    • This bridging must be installed and anchored before the hoisting cables are released.
  • When bolted diagonal erection bridging is required, the following applies:
    • The bridging must be indicated on the erection drawing. [29 CFR 1926.757(d)(6)(i)]
    • Bridge Clip
      The erection drawing must be the exclusive indicator of the proper placement of this bridging. [29 CFR 1926.757(d)(6)(ii)]
    • Shop-installed bridging clips, or functional equivalents, must be used where the bridging bolts to the steel joists. [29 CFR 1926.757(d)(6)(iii)]
    • When two pieces of bridging are attached to the steel joist by a common bolt, the nut that secures the first piece of bridging must not be removed from the bolt in order to attach the second. [29 CFR 1926.757(d)(6)(iv)]
    • Bridging attachments must not protrude above the top chord of the steel joist. [29 CFR 1926.757(d)(6)(v)]
  • During the construction period, the employer placing a load on steel joists must ensure that the load is distributed so as not to exceed the carrying capacity of any steel joist. [29 CFR 1926.757(e)(1)]
  • Except as noted below, no construction loads are allowed on the steel joists until all bridging is installed and anchored and all joist-bearing ends are attached. [29 CFR 1926.757(e)(2)]
  • The weight of a bundle of joist bridging must not exceed a total of 1,000 pounds, and [29 CFR 1926.757(e)(3)]:
    • A bundle of joist bridging must be placed on a minimum of three steel joists that are secured at one end.
    • The edge of the bridging bundle must be within 1 foot of the secured end.
  • No bundle of decking may be placed on steel joists until [29 CFR 1926.757(e)(4)]:
    • All bridging has been installed and anchored.
    • All joist bearing ends are attached, unless all of the following conditions are met:
      • The employer has first determined that the structure or portion of the structure is capable of supporting the load. This determination must be made [29 CFR 1926.757(e)(4)(i)]:
        • By a qualified person.
        • Documented in a site-specific erection plan.
    • The bundle of decking is placed on a minimum of three steel joists. [29 CFR 1926.757(e)(4)(ii)]
    • The joists supporting the bundle of decking are attached at both ends. [29 CFR 1926.757(e)(4)(iii)]
    • At least one row of bridging is installed and anchored. [29 CFR 1926.757(e)(4)(iv)]
    • The total weight of the bundle of decking does not exceed 4,000 pounds. [29 CFR 1926.757(e)(4)(v)]
    • Placement of the bundle of decking is within 1 foot of the bearing surface of the joist end. [29 CFR 1926.757(e)(4)(vi)]
  • The edge of any construction load must be placed within 1 foot of the bearing surface of the joist end. [29 CFR 1926.757(e)(5)]