Design of Concrete Sleepers
Design of Concrete Sleepers
(OP)
Hi,
I'm designing a concrete sleeper which will support a 78" dia pipe and several smaller pipes (2" to 6" dia). The sleeper looks like a wall footing with length equal to 21' and height of 8'-8". Its (wall-like) pedestal is 18" thick.
The 78" dia pipe has high anchor loads (lateral loads normal to pedestal) but the pipe shoe which transfer the lateral loads from pipe to pedestal is only 8". For shear and flexure design of pedestal, what effective width should I use? I'm doubtful to consider the whole pedestal length to provide shear and flexural resistance. Am I correct?
Your responses will be highly appreciated. Thanks!
I'm designing a concrete sleeper which will support a 78" dia pipe and several smaller pipes (2" to 6" dia). The sleeper looks like a wall footing with length equal to 21' and height of 8'-8". Its (wall-like) pedestal is 18" thick.
The 78" dia pipe has high anchor loads (lateral loads normal to pedestal) but the pipe shoe which transfer the lateral loads from pipe to pedestal is only 8". For shear and flexure design of pedestal, what effective width should I use? I'm doubtful to consider the whole pedestal length to provide shear and flexural resistance. Am I correct?
Your responses will be highly appreciated. Thanks!






RE: Design of Concrete Sleepers
1) Use ACI Appendix D for the anchorage design.
2) For flexure, assume a 30-45 degree load spread to the base.
3) Shear is the tricky bit. First, I'd figure out how close to the top I could get with one way shear working over the load spread area mentioned above. Then I'd check lateral, slab edge style punching shear on the section of wall above.
A sketch would help. I'm not entirely sure that I understand the situation.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Design of Concrete Sleepers
I think you're on the right track. I'll attach a sketch for clarity.
I have assumed a width 3 times the wall thickness which will make my design over-conservative considering your assumption of 30-45 degree load spread to the base is correct. Can you support that assumption with a reference? I want have a clear picture of the principles involved in order to design such structures more economical.
RE: Design of Concrete Sleepers
1) PCI handbook
2) UK concrete code
3) SDI composite deck manual.
For strength purposes, you can always design in a distribution beam at the top of your wall and then distribute your loads laterally as far as the capacity of that beam will allow. In your case, you can probably have the width of the whole wall for the sake of a few 20M at the top.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Design of Concrete Sleepers
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Design of Concrete Sleepers
You could always make the support plate fixing into the concrete better and bigger?
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way