Deep Precast Manhole Design
Deep Precast Manhole Design
(OP)
Have to look at a 25 foot deep 54" precast manhole to see if special reinforcing is needed. Seems to be just a ring analysis with uniform loading, the allowable concrete compressive force not to be exceeded, using minimum steel.
That being said, does anyone ever use allowances in their design for uneven compaction of the manhole that would yield uneven lateral pressures, possibly necessitating steel other than the minimum? Seems to me that the loading would almost never be uniform.
Modeling this in RISA would be as b)(%& to allow movement of the walls, but doable.
That being said, does anyone ever use allowances in their design for uneven compaction of the manhole that would yield uneven lateral pressures, possibly necessitating steel other than the minimum? Seems to me that the loading would almost never be uniform.
Modeling this in RISA would be as b)(%& to allow movement of the walls, but doable.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com






RE: Deep Precast Manhole Design
Check out this link.
http://www.concrete-pipe.org/pdfdd/DD_20.pdf
RE: Deep Precast Manhole Design
RE: Deep Precast Manhole Design
I kinda felt that the variation might only apply to larger diameter structures, but felt that it could be based on the diameter to thickness ratio of the manhole too.
This manhole is apparently only 4" thick, which, intuitively, seems too thin for the load. I'll run the numbers though. Thanks again.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com