MANHOLE DESIGN
MANHOLE DESIGN
(OP)
Hi Engineers,
I have design a manhole using plates and have some doubt. I would be glad if someone could clarify this for me;
1) how do i find the maximum bending moment and shear forces in the plate for my rebar design?
4) I did considered the active case in my design using surcharge load and a backfilling load both applied separately to walls. Is am i doing the right thing?
3)my base pressure is more than my bearing capacity of the soil and i don't want to increase the base nor introduce piles. What will be the appropriate solution to this?
I have design a manhole using plates and have some doubt. I would be glad if someone could clarify this for me;
1) how do i find the maximum bending moment and shear forces in the plate for my rebar design?
4) I did considered the active case in my design using surcharge load and a backfilling load both applied separately to walls. Is am i doing the right thing?
3)my base pressure is more than my bearing capacity of the soil and i don't want to increase the base nor introduce piles. What will be the appropriate solution to this?





RE: MANHOLE DESIGN
Dave
Thaidavid
RE: MANHOLE DESIGN
Please see attached. Will this help?
RE: MANHOLE DESIGN
1) The lift-out top cover plate can be treated as a free rectangular plate, pinned on all four sides. The formulas for stresses from various loads are in Roark's handbook of formulas. The relative proportions and thicknesses of your walls and base appear to be appropriate.
2) If the surcharge load is as large as you show (wheel loads, perhaps), then those will likely be a part of the governing load case equation. Their Boussinesq pressure will add to the active soil pressure case.
3) The answer to this depends on the specifics. If the difference between the actual and the allowable soil stresses is nominal, then site improvement of the in-place soil may be sufficient to get you to an allowable situation. If that is not going to be sufficient, then you must revise either the geometry (the base size), or the support system. As you mentioned, driven piles would be one way to do this. There are several options to think about (among others):
a) undercut and remove the existing soil, and replace it with good soil, properly compacted
b) install compaction piles
c) install drilled caissons
d) installed micro-piles
Thaidavid
RE: MANHOLE DESIGN
RE: MANHOLE DESIGN
RE: MANHOLE DESIGN
RE: MANHOLE DESIGN
Mike McCann, PE, SE (WA)
RE: MANHOLE DESIGN
RE: MANHOLE DESIGN
Thanks.
RE: MANHOLE DESIGN
This was done using StaadPro. Find attached the file.
RE: MANHOLE DESIGN
Do you have a supervisor? Really, they should be training or mentoring you on the right tools for the right job. You don't use dynamite to dig a hole for a rosebush and you don't use a finite element program for a little manhole. It's not necessarily wrong, it's just overkill.
RE: MANHOLE DESIGN
RE: MANHOLE DESIGN
Your model shows an understanding of structural engineering. Dust off that structural engineering handbook, find a simple/simple concrete beam analysis and design and go to town.
RE: MANHOLE DESIGN