Four anchor rods per column
29 CFR 1926.755(a) requires every column to be anchored by a minimum of 4 anchor rods. A base plate with 2 rods fails; 2 is half the minimum. The minimum is 4, not 6.
The anchorage must resist a 300 lb eccentric gravity load located 18 in from the extreme outer face of the column. That load never reduces the rod count.
Locating the 300 lb load
The 18 in is measured from the outer face. Add half the column depth to get the distance from the centerline.
- Column 12 in face to face: the face is 12 ÷ 2 = 6 in from the centerline, so the load sits 6 + 18 = 24 in from the centerline.
- 18 in treats the face as the centerline; 30 in measures from the opposite face.
Two bolts before the hoisting line is released
Under 1926.756(a)(1), before a beam's load is released from the hoisting line, each connection needs at least two bolts of the same size and strength as shown on the erection drawings, drawn up wrench-tight or the equivalent specified by the structural engineer of record.
- One bolt per beam end fails, however tight.
- Drawings show 3/4 in bolts: two 5/8 in bolts fail. Tightening or a third undersized bolt does not cure the wrong size.
- Equivalents come from the structural engineer of record, not a field competent person.
- It does not require every bolt installed and fully tightened before release.
Diagonal bracing: one bolt per connection
Under 1926.756(b)(1), solid-web members used as diagonal bracing need at least one bolt per connection. This exception never covers beams.
- Beam with two end connections: 2 × 2 = 4 bolts.
- Solid-web diagonal brace with two end connections: 1 × 2 = 2 bolts.
- Total before both are released: 4 + 2 = 6.
Traps: 4 gives the beam one bolt per end, 8 treats the brace like a beam, and 3 counts per member instead of per connection.