RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
(OP)
Do you guys know of any reference or guidance to use to design a reinforced concrete cradle or a reinforced concrete slab on top of an RCP? Basically, a road on top of an RCP is going to be lowered to about 6 inches or 1 foot above the RCP and I want to make sure the vehicular loading does not damage the RCP. Thanks






RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
Can you please explain, what you mean by support point. Do you basically have the slab extending beyond the pipe, then at the end of the slab you have a thickened concrete section?
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
http://eng.lacity.org/techdocs/stdplans/s-200/s255...
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
Option A is a crossing slab, Option B is more of a box culvert.
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
For new pipe, the most cost effective option is usually to increase the RCP wall thickness. For an existing pipe, the first step is to determine the RCP wall thickness.
See the RCP Fill Height Tables published by the American Concrete Pipe Association.
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RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
reinforce the slab
extend the footings on either side of the pipe to at least top of pipe or better yet, to the springline. they dont need to go clear down to the bottom
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
If I assume a Class III (1350-D) pipe was provided, Ordinary Bedding (Class C Bedding) used and use the HS 20-44 for the vehicular loading and impact loading I get about 270-D just using 8 inch of soil with a unit weight of 139 pcf above the pipe. Based on this information the pipe would be alright with just 8 inches of soil above since 270-D is less than the 1200-D provided on the plans. But not sure if providing just 8 inches of soil above the RCP would be appropriate.
Thanks
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
No. The Styrofoam will have to cross the pipe (6'), then extend at least 3' beyond it on both sides. That means the 7" thick reinforced slab will have a clear span of approximately 12' and must carry highway loads... no way. The necessary vertical clearance is just not available to make that solution work.
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RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
www.americanconcrete.com
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
www.SlideRuleEra.net
www.VacuumTubeEra.net
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
I was looking at the height of fill (d-load) tables from the american concrete pipe association and noticed that they provide designs for pipes with 1 ft of fill and HL-93 loading. Based on this information if I only place 1 ft of fill above the top of the pipe that would be acceptable and would not require the concrete thicknesses previously suggested. Do you guys still think I need the concrete protection? Why would those tables indicate that 1 ft of fill above the pipe is acceptable for vehicular liading (HL-93)? I am not trying to question your guidance, just really want to understand this topic.
Thanks
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
Well, you need a wearing surface. Can't just put traffic on the fill and expect it to last. Loadings, like HL-93, were developed for bridge design where, by definition, there is a wearing surface (the top of the bridge deck, if nothing else). It is reasonable to apply the loadings to roads (with a wearing surface), too.
As I mentioned 8 days ago (2 Aug 16 19:08), with the proper combination of pipe wall class and bedding only one foot of fill and the road (wearing surface) itself may be needed. That recommendation still stands. Since then, you have performed some investigation, made (unsupported, but reasonable) assumptions, and good questions... which have received direct answers (not guidance).
IMHO, the fact that you found a record of the original D-load design suggests that the pipe is class III, or higher.
Try to field verify pipe condition.
Confirm the bedding properties by having some soil testing performed.
If the test/inspection findings and (conservative) pipe-class/bedding/highway-loading calculations checkout... accept the results and proceed. There are occasions for "engineering judgment" and "gut feel", but not if objective measurements can reasonably be performed. With that said, no, I don't believe a concrete bridging slab is needed for 12" of fill and the pipe/bedding conditions described.
To better understand the topic, a good place to start is to buy (and study) the appropriate books from the American Concrete Pipe Association.
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RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
Any simple reference to prove that the pipe will bear the additional stresses from the loads acting on the above mentioned foundation?
Thanks
RE: RCP - Design for Cradle or Concrete Slab on top of Pipe for Vehicular Loading
You can insulate the outside part of the 'wall' and extend the insulation horizontally. Or, starting from about a foot down, insulate horizontally. Use extruded polystyrene, Type 4.
Dik