The problem is that you somehow get a negative term in arctan and the solution have to be positiv.
Try the absolute value of the term in arctan (im not sure if this works) or the following formula, its from "Bodenmechanik und Grundbau, Lang Huder Amann Puzrin".
I get about I=23% which should...
The following books cover a wide range of failures (course books of a lecture at university). However not very recent, but each topic has a theory section and a short back of the envelope calculation with the real numbers. Very comprihensible and there is also a capter about the leaning tower of...
Do it the graphical way as you would derive the orginal active earth pressure:
Vary omega till you get the bigges Earth Pressure E under equilibrium. The only difference to the known solution is the way you calulate the force of the soil G (which now is somehow restricted). You wont need a lot...
Maybe you can look into a folded plate/shell structure (and not a beam).
With a quick google search: Groenendael Hippodrome or madrid grandstand from Andre Paduart. "a 13.5m cantilevering folded plate with a thickness ranging from 7 to 12cm only".
Quite impressive.
How big are your holes? Kind of a pipe diameter up to 30 cm/1 foot circular/rectangular or more of a staircase opening?
I wouldn' care that much about the former and just apply the code.
ACI says pretty much the same as CSA (10d).
Modelcode 2010, eurocode and swisscode says 5.5 to 6d distance...
steveh49 is right about the centroids make a slight difference.
However, the Autodesk Bridge method does not have to be wrong.
If you consider a simple cross section like the following, its all about to sum up all the forces with the right lever arm, but for the calculation itself it does not...
Hi
It doesn't matter "around" which point you calculate your bending resistance.
You calculate it about the neutral axis, the ASBD maybe around the bottom reinforcement. In the end its the same.
Your x is way off:
Simple calculation: As_bottom*fsd = 2100*0.435 = 913 kN
N = -300 kN
Fc_sum =...
You should be ok with 1.5d as postulated in EC or modelcode 2010.
However for "long columns" or wall ends/corners we check the area of the red line like normal one-way shear along a common wall and the ends separately for punching.
The wall-ends we split up in sectors as below, so you don't...
