Live Load on Marine Dock

[Lutfi]

Based on ASCE 50, the recommended live load on marine dock is 100 psf else use local code. The marine dock is for small crafts (max boat size is 42 feet). To the best of my knowledge, FBC does not have any provision for marine docks.

Based on your experience, what do you use for live load on fixed marine docks?


Regards,
Lutfi

 

[MiketheEngineer]

Is it for parties - then 100 psf seems reasonable. If it is private - something like 40-50 seems OK.

 

[Lutfi]

It is for a marina on an air force base where access is controlled and limited (no access to public who may congregate on the docks other than casual users). I doubt if parties will be held on the dock itself since there is a club house within the marina. I am thinking that 50 psf is adequate based on the rational that within an 8 foot by 10 foot segment, assuming that you can fill it up with individual at 200 pounds each consuming 4 sf each (2’x2’) will result in 50 psf. In addition, we will design for 400 pound load over 2’X2’ area.

Does anyone see a hole in this approach?


Regards,
Lutfi

 

[nutte]

I'm not familiar with ASCE 50, but if it says to use 100 psf, why are you trying to use less?

 

[azcats]

Any chance for vehicle (firetrucks even) traffic?

 

[dhengr]

Lutfi:

If you allow people, “each consuming 4 sf each (2'x2') will result in,” you will have a large hole in your dock, if not in your approach. They should feed them better up at the club house to alleviate this potential.

Is the dock 8 or 10' wide? You might want to consider a square area if it can be 10x10. Watch concentrated loads (your 400#) on joists or stringers. Many marinas have foot lockers at each slip, filled with what? You may want to consider a fair sized maintenance vehicle out their, a 42' boat has a pretty good sized engine which might need work or replacement.

 

[JAE]

I would use the 100 psf - a dock has some features that go beyond an "office floor" loading of 50 psf:

1. Possibility of LOTS of folks running onto the dock, with equipment, in an emergency....more like an assembly type loading.

2. Possibility of exterior long term degredation of the materials, being near water, thus - a higher live load gives me a dock with more capacity should some of that capacity be diminished.

3. Boat impact over time - that may not affect the repetative joists, etc. but might affect beam to pier connections, etc. A higher LL again provides a more substantial structure and connections.

 

[Lutfi]

Thanks for the input to all. Here is some feedback:
1. The term dock that I used in not the proper term. It is a pier (a main pier and finger piers).

2. There will be not heavy traffic on the piers such as equipment or machinery.

3. I am debating the 100 psf for economic reasons. I believe that I owe it to my client to give them optimal, efficient, code compliant and cost effective design while I can go to sleep at night.

4. LoL at dhengr at my use of "consuming". That is a good one. PT wood does is not filling at all. I should have used "occupy an area". The foot locker areas will be designed for 125 psf because I am treating them as storage. The pier is 8 foot wide and the piles are spaced at 10 on center. That is why I sued the 8'X10'. I am being told that engine work will not be done on the pier.

5. JEA, as always, you are great to brain storm with. You raise good points that were and will be considered.

6. I am not able to find anything loading requirement in Florida. If anyone knows of one, I would appreciate it them letting me know. The facility is located on DoD property which uses the UFCs and the IBC. UFC 3-152 has live load requirement of 40 psf and 100 psf depending in access to the public.

Great responses and forum. Thanks to all.


Regards,
Lutfi

 

[dhengr]

Lutfi:

Since this pier is on DoD property, you might want to look to the Navy literature, maybe NavDocks or something like that. They have some really good design specs. and guide on dock/pier design, generally thinking a lot bigger than you are, but they may have something on your size pier too. The boat force magnitudes may change, but the design principles will not change. I wouldn’t ignore the possibility of light emergency vehicles (fire or health issues, etc.), when they see the fire, they aren’t going to call for your permission before they go. Put concrete filled pipes at the entrance if you mean to prevent this.

 

[boo1]

TM 5-850-1 manual establishes criteria for guidance of Corps of Engineers personnel in the planning and design of proposed military ports.

http://www.wbdg.org/ccb/ARMYCOE/COETM/ARCHIVES/tm_5_850_1.pdf

Unified Facilities Criteria UFC 4-150-06 12 December 2001 cites and supplement existing government and commercial standards for design and construction of harbor and coastal facilities.

http://www.wbdg.org/ccb/DOD/UFC/ufc_4_150_06.pdf

UFC 4-152-01 handbook provides basic design guidance for pier and wharf construction.

http://www.wbdg.org/ccb/DOD/UFC/ufc_4_152_01.pdf

 

[MiketheEngineer]

I was thinking this was for Joe Fisherman - where I would be inclined to use a 40-50 psf LL - like a residential deck.

BUT for the USAF - I would definitely use 100 psf. IF they can afford a $600 toilet seat - I would think that a couple of toilet seats will easily cover the costs....

 

[JAE]

Maybe this dock/pier IS a toilet on a grand scale. The top brass walk out to the end, bend over and ...

 

[MiketheEngineer]

BTW - the Coast Guard has quite a manual describing just about anything built on the high seas. Not sure if this is the case or they cover this particular area. It can be downloaded and no - I don't' have the link - sorry. Google time - once again.