4.7 COMPLETING AND PLUMBING THE FIRST BAY OF THE STEEL BUILDING

After the first intermediate or interior frames have been set, General steel recommends that all purlins, girts, and eave struts be installed in the braced bay and the entire bay plumbed, aligned and braced before proceeding further. If the building is designed without cable bracing. the erector is responsible for providing temporary erection bracing.

When this bay is properly and accurately plumbed and braced, the remaining members, to a large degree, will automatically plumb and align when installed. Only a final check of the building plumb remains, and few adjustments, if any, will be necessary.

Plumb the frame with a plumb bob or transit, not a spirit level. To measure lateral plumbness hang plumb bob from top of the column down the outside flange as shown below. Adjust plumbing cables to obtain equal tape measurements at top of column.

To plumb the braced bay without a transit, run a chalk line from out of flange to out of flange of columns on the foundation (per drawing). Drop plumb bob(s) from rafter flange(s) and square the frame using the rod bracing for leverage.

To plumb the braced bay lengthwise using a transit, sight in the transit parallel to the base of the steel building frame columns by using a position a few inches from the frame line (See sketch). Make sure transit is level. Check frame by reading tape through transit. First bring columns into plumb, then rafters, by adjusting diagonal bracing. Take all measurements from centerline of flange. Take a measurement at the base of the columns and adjust the bracing to correct the transit reading at the rafter measuring location. Once the frame is plumb, all connection bolts and anchor bolts should be tightened.

Erecting the Column and Beam Endwalls >>