what type of building? for protal frames I find that it varies depending on wind cat, the higher the wind cat the lower the spacing, varying from 6-11m.
ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”
If you are in the US and using open web steel joists, keeping the joists to 40' or less will not trigger the OSHA requirements for them to be bolted to the girders.
This is a huge time and money savings for both fabrication and erection.
I do not have the notes in front of me, but a guy named Steve Ashton (of SEAKM and his own consulting biz) does a presentation on the topic of efficient steel layout. We had him at SEAoT-Dallas this year.
I can't resist pointing out the obvious, like it depends on loading and available depth of structure...
Framing in the shorter dimension can be beams and longer direction can be girders if you have adequate girder depth. Use the opposite if you have limited depth or want a uniform depth. Serviceability (deflection, vibration) becomes controlling on long bays, so select for L/D. Even a square bay will be efficient for some layouts.
Beams of the same depth as girders provide better bracing, especially spandrels.
Locate beams so you get an even number instead of odd, this moves the loads closer to supports (draw a FBD, it'll make sense.)
Remember that uniformity of members cuts detailing, shop drawing review, fab, staging and construction costs, so less steel is not always better. Avoid excessive complexity in the layout, and keep all similarly-situated beams the same. Keep column size and orientation consistent. Keep bay size 100% consistent - a less than one inch difference means new beam and girder marks. Keep girders and beams 100% consistent when possible (fewer shops, fewer marks on plan and in the field, and less lay-down area for staging.) Keeping layout consistent keeps loading consistent, which keeps connections consistent. Seemingly insignificant changes will result in profoundly more complexity in detailing, shops, and fabrication.
Single angle connections can save time and money, and improve construction safety.
For braced frame, regularly and symmetrically spaced braced frames means you can use the same details for each frame instead of having to design each one separately. This cuts design, detailing and fab time.
Avoid moment frames unless flexibility is good for your uses. Use bolted moment connections unless your contractor prefers welding - I have had small jobs that were almost entirely welded and a good crew can be good and fast. Obviously, don't combine field welds and bolts in the same connection unless you neglect erection bolts (always leave the bolts in place.)
Select optimum bay sizes.An exhaustive study by John Ruddy, P.E., of Structural Affiliates International in Nashville (AISC Engineering Journal, Vol 20, #3, 1983) indicated that a rectangular bay with a length-to-width ratio of approximately 1.25 to 1.50 was the most efficient. The filler members should span in the long direction with the girder beams in the short direction (see figure 2).
I think with that rule of thumb see what the architect is going to give you for column spacing and do a quick typical bay study to see what is optimum....
This is a bit elementary but a nice little guide/study for a steel-frame office building:
Parametric Bay Studies v4.1
This tool helps engineers answer questions such as: “Is it less expensive to increase the size of the beams than to camber?” and “Is it more efficient to frame the beams in the long direction or the short?” Parametric Bay Studies v4.1 designs a typical bay in a composite steel framed structure and optimizes the design for either the overall weight or the relative cost of the framing system.
SteelTools offers automated calculators that can help designers arrive at the optimal design quickly and easily. Floor Framing v13.0 compares various costs to find the most efficient bay framing layout. There are many helpful spreadsheets and tools available for free download at
