analysis theory for retaining wall
analysis theory for retaining wall
(OP)
hi guys,
I designed a besement like structure a few weeks ago, I did the initial bending moment calculations assuming the walls as cantelevers( the roof can be removed), only taking into account the pressure of the soil.
I then checked it on Prokon2.2 as a retaining wall and got the same moment I did with my hand calculations as the maximum moment for the base. But the max moment for the wall part was a full 23KNm less. The structure has no toe, the wall and floor differ 50mm in depth.
I compared this to other engineers designs in our company with the same program, there is always a difference in BM.
Does anyone have any insight on this? Is there something I'm missing?
Someone told me the axial force in the wall reduces the BM, I read something like that but couldn't confirm, and not by that much.
I designed a besement like structure a few weeks ago, I did the initial bending moment calculations assuming the walls as cantelevers( the roof can be removed), only taking into account the pressure of the soil.
I then checked it on Prokon2.2 as a retaining wall and got the same moment I did with my hand calculations as the maximum moment for the base. But the max moment for the wall part was a full 23KNm less. The structure has no toe, the wall and floor differ 50mm in depth.
I compared this to other engineers designs in our company with the same program, there is always a difference in BM.
Does anyone have any insight on this? Is there something I'm missing?
Someone told me the axial force in the wall reduces the BM, I read something like that but couldn't confirm, and not by that much.






RE: analysis theory for retaining wall
The difference in bending moment may be due to differing earth pressure co-efficients, different assumed unit densities (I take water as 10kN/m^3 and soil as 19kN/m^3...It is too late at night to convert these units to imperial), or moments are taken at different locations. Personally, I like to analyse a wireframe modelled to centreline goemetry, this will give a greater moment than it would if the moment was calculated at the top of the slab, opposed to centrelines.
RE: analysis theory for retaining wall
As for the axial load, it is the weight of the wall. It is negligible in this case, but some of my colleagues says that axial force can reduce moment if the axial force is enough?
anybody maybe have any material or explanations for this?
I tried explaining it with a wireframe analysis, but only deduced that as far as negligible forces go the weight of the wall will act as a destabilizing force with slight deflection.
RE: analysis theory for retaining wall
RE: analysis theory for retaining wall
The axial force has a beneficial effect on the wall with regard to the bending moment capacity. Your wall can take more flexual load when there is a vertical stress, but again this vertical load has no effect on the bending moment demand, only increases the capacity.
Cheers,
YS
B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...
RE: analysis theory for retaining wall
Dik
RE: analysis theory for retaining wall
Are your colleagues assuming soil/wall friction in their calculations?
A portion of that is treated as axial load.
RE: analysis theory for retaining wall
RE: analysis theory for retaining wall
Has any body figured the percentage of blockage due to Permahedge ?
Not much info available from manufacturer of this product.
ASCE 7-02 stipulates as solid sign method. Any method to figure area of blockage to total area of Permahedge.
RE: analysis theory for retaining wall
2) Start a new thread.
3) Huh?
(to avoid blockage, do not consume Permahedge)