Parking garage analysis and design

[S R P]

Hi,

I have been asked to review an existing two story wood structure which is about 100 years old. The client's intention is to use the structure for parking facility.
IBC load requirement is just 40lb/ft². I tried to find some design guidelines for parking garage, but could not.

I do not have a lot of parking garage design experience. Further, this is a wood structure sitting on 10 x 10 columns spaced 21 ft O.C.. Client wants me to propose any modification for the structure to suit for parking. I have a few questions:

1. Could someone please send or list me a good parking garage design guidelines. If you have examples, that would be much better.
2. Would you use wood columns for parking garages?
3. In addition to 40psf live loads which is very low, how would impact loads act on the structure, due to possible braking vehicles and as such.

Thank you

 

[Lomarandil]

Haven't done one myself, but WBDG might be a good starting point for some of the big picture issues.

https://www.wbdg.org/building-types/parking-facilities

In addition to the usual structural considerations, three challenges that I know of unique to parking structures are concentrated (tire/jack) loading, vehicle collision (not so much braking/gravity impact loads as horizontal) and fireproofing. I would suspect that wood column connections would be a limiting factor for collision, and that fireproofing could be challenging in wood also. Maybe both solvable issues, but it doesn't surprise me that it's not a common structural system.



----
just call me Lo.

 

[dik]

High-Lo:

It's an excellent and well written article. Time permitting, I'll take a gander at it and see if I can add any comments. During the last 50 years I've been involved with 20 or 30 parkades, including planning and layout and restoration.

Dik

 

[S R P]

Thank you Lomarandil and Dik for your replies. Your reply also pointed into a good point - connections. I may need to pay more attention on it again. Because this structure is located in coastal area, I am not sure of the connections are still in good condition.

Further, lateral loads such as impact/ braking etc., how would you address into that?

What kind of bracing would you recommend?

 

[phamENG]

I'd also be concerned with the long term viability of the wood in that case. Maybe it's been enclosed and so the wood is still in great shape? Well parking garages have very strict ventilation requirements. If these will be met by opening the structure to outside air, I'd be worried. I'm assuming this is on the Texas Gulf Coast - letting all that damp air in could compromise the wood structure in the future. Rust in connection hardware as well as rot in the wood itself.

 

[dik]

SRP:
"Further, lateral loads such as impact/ braking etc., how would you address into that?"

For small structures, definitely... for most parking structures, I don't.

Dik

 

[Canuck65]

In addition to the UDL loading, one must consider point loads. The point load criteria should be codified in your USA codes. Typically this is one common area where a wood structure will have problems meeting the basic load requirements for a parking structure. Wear course would be another item to consider. Likely a waterproofing system and wear course would be required. There are many common wear course systems for concrete structures, not sure how they would hold up on a wood structure. As mentioned above, fireproofing would likely be a big issue. In such an old structure, all the detailing would have to be reviewed ... every last detail of the load path. You may very well need to put a concrete topping on the existing wood floors to justify some of the point loading. Can the existing structure take the additional dead load?? Presumably you would have to add ramps between levels that don't exist now.

While you may get through the calcs and somehow justify it structurally, you would need to sit back and think about it. This would be a one of a kind, unique structure (at least in my area) ... and that would make me pause to think about whether or not it was a good idea. There is a long list of obstacles to overcome. The closest things I have seen work are: A) an early 1900's car assembly factory, the floors were laminated timber on wood beams/columns (squeezed about 50 psf live load capacity out of the floors), or B) laminated timber decks that are used on older bridges.

 

[KootK]

Some great, non-wood parking design guides inlcude:

PCI's Parking Design Guide (concrete)
PTI's Parking Design Guide (concrete)
AISC's Parking Structure Design Guide (steel)
The general purpose book by Chrest shown below

While I don't believe that any of those guides cover wood, I'd still recommend reviewing at least one of them to get a sense for the design criteria involved irrespective of the material used.

 

[r13]

Will this be a vertical/valet parking facility, or typical drive through parking garage? Huge differences, I believe.

 

[S R P]

Thank you all.
@Retired13-This is going to be used as a typical drive through parking garage.

 

[r13]

S R P,

An interesting article regarding parking garage. Please read on. Link

 

[Teguci]

3 kip point load to simulate a jacking load.
Consider drainage and water protection.
Check your columns against impact or protect/guard them (good luck).
and "Parking Structures" should get your mind going regarding maintenance, parking flow, as well as structure. I could picture Tony Chrest yelling at someone who proposed a wood parking garage.

 

[r13]

Another reading material is the mild objections from Dr. S. K. Ghosh regarding the change of load combination by ACI 318-02, and the reduction of parking facility design live load from 50 psf (ASCE7-98)to 40 psf (ASCE7-02). Link

 

[dik]

Teguci:
"Consider drainage and water protection."

This is very important. The other ones not generally considered unless you have light columns. For alternating live loads, I usually consider LL= 20 psf. If you filled a parkade, bumper to bumper, including isles, you would not get 20 psf.

Dik