CANTILEVER RETAINING WALLS 2

[tbone73]

I'm designing some cantilever retaining walls where there is a slab on grade located on the heel side. This slab is a sidewalk for pedestrian use only, in fact no roads or driveways are located near these walls. I've looked at the IBC and it indicates for sidewalks to use a 250 psf live load surcharge. This values seems more likely for areas where heavy trucks are in use. Should this value in fact be used, it seems a little too conservative? Any input is appreciated, thank you.

 

[a2mfk]

Off the top of my head, that sounds like what I have used in the past for parking lots or areas that will have actual truck traffic. Probably what they are anticipating is occasional maintenance vehicles, as people can and will find ways of driving on sidewalks. But just common sensing this, what scenarios would result in a 200psf LL on a sidewalk (if you subtract 50 psf for the 4" slab weight)?? Will the sidewalk frequently handle participants on The Biggest Loser, or maybe an NFL team?

 

[Splitrings]

That is the same value the AASHTO Bridge Design Specification uses for highway surcharge loads on retaining walls. It states a min. of 2 feet of equivalent soil height shall be added and the min. weight of soil shall be 0.125 ksf.

 

[paddingtongreen]

Are you required to design to IBC? Yes or no, case closed.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[cap4000]

The 250psf is in case cars and light trucks somehow end up on the sidewalk.

 

[hawkaz]

250 psf is for sidewalks subject to trucking loads (straight from the IBC). If no trucks (especially fire trucks) can have access to drive on this- then I would consider using 100 psf surcharge (yard and terrance,pedestrian loading). If a fire truck could jump a curb and drive along the wall, then keep the 250 psf requirement.

 

[tbone73]

Thanks all for the input, I appreciate it. I tend to agree with hawkaz and a2mfk. These sidewalks are located away from driveways or roads and are not very accessible to vehicles at all.

 

[SteelPE]

When considering issues like the one you are, I always find that it's better to design for the additional load.... after all, accounting for the load now is easy as to trying to repair the wall in the future.

In the end, you may be adding a little extra steel in the stem and you may make the footing slightly larger. As long as you are not talking about a 20' tall wall, the surcharge will not increase the sizes that much. Account for the load and sleep better at night.

 

[BigH]

Sometimes codes are the cart leading the horses . . .

 

[cap4000]

Splitrings

Take a look at pg 94 of 592 from the link below.

http://www.engmath.dal.ca/risk/pubs/FHWA_Manual.pdf

 

[Splitrings]

Cap4000,
The current AASHTO LFRD Specification has two tables; one for traffic perp. to the wall and one for traffic parallel to traffic. The table in the FHWA reference appears to match the table in AASHTO for traffic perp. to the wall. In the AASHTO reference for walls parallel to traffic, it only requires 2 ft of additional soil for the surcharge as long as the load is at least 1' from the wall.

 

[tbone73]

SteelPE, very valid point of view, and I will consider this. Thanks for the link cap4000. Again Thank You All for your input, valuable indeed.