Bay Spacing/Column Spacing for 36'-40' Big Box Warehouses

[mdschulte]

Hi Everyone!

My name is Michael; I am a material handling engineer, based out of SLC, UT. I am looking to better understand what structural engineers and architects consider when spacing building columns/bay spacing in these types of warehouses - speculative big box fulfillment centers, clear heights of 36'-40' . The internet has regurgitated versions of this from someone well known in the material handling industry (Jim Tompkins):

"Poor space utilization: Generally, columns are spaced apart at 40 feet, 50 feet, or some other similar measurement. Architects and structural engineers habitually use these lengths in designing building configurations because steel mills generally produce structural members in these lengths. Often times, however, these dimensions result in a column line landing in a designated path of travel."

In Salt Lake City, I find that it is common to have any where between 50' and 58' column centers when the clear height is in that 36'40' realm. I especially see a lot of 54'x50' bay spacing. Additionally, I've received feedback that 12"x12" columns are preferrable and cost less than the 10"x10" columns. Thought that was interesting.

Would love to hear your thoughts on the following:

1. What are your high-level considerations on bay spacing and building column placement?
2. What is the longest span or length interval you'll consider for a 40' clear building (that is economical)
3. Are there any papers, articles, books, etc. that you would recommend for this topic?

Thank you so much!

 

[driftLimiter]

This is really an architectural consideration more than structural.
Archs will tell us what they need (we don't ask why). Then we make it happen.

I can tell you open web steel joist framing is economical for bay spacings in the range around 50 ft. Its really the go to solution for that.

Columns on the order of 12" square HSS seems reasonable to me. I don't like to skimp on columns.

 

[human909]

I disagree that this is "really an architectural consideration". Better economy can be gained by improving spacing. If is was only an architectural consideration then we'd have could have 100m wide bays with 50m bay spacing.

There are optimal engineering arrangements. I'd expect that many typical local design would be somewhat close to that optimal range. Snow loadings or wind loadings obviously have a very significant effect so what is optimal in one locality might be significantly different in another.

 

[driftLimiter]

The only reason I say that is because if the arch wants 100m x 50m then me saying its more economical to go 20m x 20m isn't going to do anything.

Sure for a certain style of building there are some sweet spots. The OP's case I think his sweet spot will be between 50ft and 60 ft.

Obviously more columns = more economical roof system that should be a given. But the arch needs clearances and he/she are the ones who has to define them.

Any big warehouses I have worked on the Arch set the column spacings well before I get ahold of it. Then I start by checking girder depths and if there isnt enough clearance we have a talk. Either move the roof up or reduce column spacing.

 

[Aesur]

There are in my opinion two ways this tends to go:
1. The building is designed generically and the design team doesn't know what tenant will be in the building. In This scenario if it's unknown then the bay spacing is typically either set by the architect, or the engineer is brought in early enough and paid to do some bay size studies and the owner selects the option they want to use, typically the cheapest solution. When looking at sizing of bays, typically you want to try to break the building into equal size bays both transverse and longitudinally to save costs on framing. If you have hundreds of the same steel joists it's cheaper than a many different sizes. Other considerations include height to bottom of steel, both for fire ratings, sprinklers, and clear height for forklifts etc.

2. The tenant is known and they provide the desired dimensions and work with the architect on the layout of the interior, thereby governing where columns can go. This case is the lest common to occur.

 

[JAE]

We used to have a client who built large freezer/refrigeration warehouses all over the country and the guiding principle in setting their column layouts were their storage racking systems.

The racks were a set width for pallets and set baseplates, anchorage, etc.

They'd layout their rack plan and we'd drop in columns at a set rhythm to match the racks and not end up with a half-rack space due to the columns.
The aisles between the racks were also included and we ended up with a 32'-4" bay layout in both directions.

They could have added an extra rack set in each bay, pushing the columns further apart but never did.

So I guess it was an "architectural" reason essentially. We even had an on-going steel fabricator constantly running numbers and providing advice to minimize costs with regard to columns, beam cantilever lengths (continuous beam runs with in-span splices), etc.

 

[lexpatrie]

There are some decent articles on material handling facilities but I don't even recall the name, high stack automated storage is my description.

There is a motion afoot to integrate the rack and use it for support of the roof, and they also like to muck around with a "slab" foundation.

Not sure if that is your situation.

Generally as HSS columns go, the larger sections will offer greater strength, wall thickness plays a role in most engineers tastes, but if you've ever been in a grocery store, that column spacing doesn't "work" with the equipment below because the equipment below isn't worked out before the structural engineer is engaged, if you ask me. Involve a structural engineer earlier and your results will change. Insist on 10 x 10 inch columns and the grid spacing will be affected (closer).

Larger column sizes allowed, larger grid spacing.

 

[haynewp]

There may be some max column spacings and sizes based on seismic considerations in Utah to watch for if it's Seismic Category D and over a certain height box building. I had a big box design that I had to use very large columns in order to control the drift using Special Truss Moment Frames.