817 Steel Erection Safety

Beams and Columns

Diagonal Bracing

Double Connections at Columns

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, or
• A shop-attached, or field-attached seat or equivalent connection device is supplied with the member in order to secure the first member and to prevent the column from being displaced. (See Appendix H of the OSHA Standard for examples of equivalent connection devices.)

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:
• a supporting member
• the first member

Column Splices

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

Perimeter Columns

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.
• 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)

In multi-story structures, when holes in the column web are used for perimeter safety cables, the column splice should be placed sufficiently high so as not to interfere with any attachments to the column necessary for the column splice.

• Column splices are recommended to be placed at every other or fourth levels as design allows.
• Column splices at third levels are detrimental to the erection process and should be avoided if possible.

EXCEPTION: Where constructability does not allow, the above requirements can be waived. (See Appendix F of 1926.750.)

Knowledge Check Choose the best answer for the question.