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.

 

General

 

  • 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 stableduring 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 13⁄16-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)]
  • 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)]

 

Steel Joists And Steel Joist Girders

 

  • 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)]

Erection Of Steel Joists

 

  • For steel joists in Tables A and B that require bridging:
    • Attach both sides of the seat of one end of each steel joist to the support structure before hoisting cables are released. [29 CFR 1926.757(c)(1)]
  • For joists over 60 feet [29 CFR 1926.757(c)(2)]:
    • Both ends of the joist must be attached as specified in steel joists and steel joist girders. [29 CFR 1926.757(b)]
    • The provisions of Erection Bridging must be met before the hoisting cables are released. [29 CFR 1926.757(d)]
  • Only one employee is allowed on steel joists that do not require erection bridging under Tables A and B, until all bridging is installed and anchored. [29 CFR 1926.757(c)(3)]
  • Employees are not allowed on steel joists where the span of the steel joist is equal to or greater than the span shown in Tables A and Bexcept in accordance with Erection Bridging provisions. [29 CFR 1926.757(c)(4)]
  • When permanent bridging terminus points cannot be used during erection, additional temporary bridging terminus points are required to provide stability. [29 CFR 1926.757(c)(5)]

 

Erection Bridging

 

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)]
    • 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)]

Landing And Placing Loads

 

  • 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)]

Shared from: Occupational Safety and Health Administration

https://www.osha.gov/SLTC/etools/steelerection/structural.html

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