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Steel Framing Plans

The complete structural design of a steel building frame is an involvedprocess, but it begins with the laying out of a framing plan, whichcan be rather simple for many buildings. See Figure 11.42 in the textfor example of a typical structural steel framing plan.Usually the bay spacings in a steelframe are kept to about 36’ (11 m)or less in order to minimize the sizeof the beams and girders, and baysizes are kept constant exceptwhere interruptions such as elevatorshafts and stairs occur. A good wayto begin laying out a framing planis to use freehand overlays ontracing paper to try dividing thebuilding plan into a number ofdifferent sizes and shapes of bays,until one layout shows promise ofworking better than the others.Then special arrangements of beamsand girders, much like the headersand trimmers used around openingsin platform frame wood floors, mustbe designed to frame around stairsand shafts. Move lines of columnson tracing paper until you arrive ata simple, logical layout that avoids excessive irregularities. (Usuallythe architectural plan can be adjusted slightly if necessary to arriveat a satisfactory framing plan.) Check to be sure that the layoutdoes not involve excessively long spans, which are costly, or spansthat are so short that they require too many columns and/or cutthe habitable space of the building into too many little pieces.Within a typical bay, the layout of girders, beams, and deckingshould be done with the aid of the rules of thumb on page 356 of

Step 1-Find an overall bayspacing that works.

Step 2-Insert special framingaround openings, then add therest of the framing.

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the text. Select a trial depth and type of deck, and lay out girdersto support the beams or joists. Determine preliminary depths foreach of these members--are they reasonable? If not, adjust spacingsand sizes until they are.

85Name: Scale:1” = 20’ (1:250)1 square = 5’-0” (1.5 m)

Steel Framing Plans 11.2

You are designing an 8- to 10-story regional office building indowntown Omaha, Nebraska, for Associated Mutual Casualty andLife Corporation. Three possible plan arrangements for a typicalfloor of the building are shown below and on the following page.Draw a feasible framing plan over each of the plans, and giveapproximate depths for the typical beams and girders. Assumethat you will use W10 columns.

86 Scale:1” = 20’ (1:250)1 square = 5’-0” (1.5 m)