MANHOLE DESIGN

[Erasa]

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?

 

[CarlosAguera]

I assume as you are posting in the STAAD forum that you are using STAAD.Pro and have modelled your manhole using a finite element mesh, then when you review the stresses in the post processing mode, these will be based on the resolved moments and direct stresses. For rebar design, you may want to include the torsional moment MXY. There is a published method for including that by Wood and Armer. That can be included in a slab design to BS8110 in the interactive Concrete Design Mode which uses the bending moments and can use a component of the torsional moment as per the above publication. Note that art this time, it is for the design of slabs and not walls as the direct stresses are not included.

I trust that helps.