An engineering firm here in VT was found liable last year when a roof collapse happened during construction. A number of workers were injured. The collapse was due to insufficient bracing. The EOR was inexperienced, according to the media report.
Can the lid be used to provide top support to the walls? This way they act more like a simply supported member rather than a cantilever? The top would have to be installed before backfilling.
The document you refer to has a short section on uniform loading of slabs on grade. The tables that are shown actually come from the PCA document "Slab Thickness Design for Industrial Concrete Floors on Grade". This document has more supporting info including design equations.
All three planes; bottom chord, web and top chord planes, need to be laterally and diagonally braced. As mentioned above, BCSI Handbook explains it all.
The SCS Technical Release #74 uses a wall thickness to height ratio as a guide as to whether the wall is flexible enough for active pressures to develop. It states a ratio of t/H<= 0.085 is flexible enough for Ka values to be used. This TR references a paper by Karl Terzaghi.
This same TR...
You show a pinned condition at nodes N9 and N10 of your RISA model. If this represents your ground surface, it is likely much too stiff for soil backfill. If you had a slab on grade that was constraining your post, a pinned condition may be more realistic. If you have soil backfill, I would...
My geotechnical expertise is pretty weak but I am guessing the skin friction between the full concrete collar and soil is insufficient to engage the available shear strength of the surrounding soil. I just looked at the new ASABE EP486-12 and it states a "device that enlarges the base" can use...
In IBC 2003 it is in a footnote to table 1804.2. In IBC 2012 it is in section 1806.1. These increases are only allowed for load combinations that include wind or earthquake loads.
A first order analysis is done as a portal frame. Two posts and a truss in between, with or without knee braces. A second order analysis can be done by moment distribution, stiffness method, etc.
I suppose the AHJ could step outside the standard codes, but I can't imagine they would want to. If the GSL is 40 psf, the roof load for a cold, flat non slippery surface with an importance factor greater than 1 would be much greater than 40 psf. Maybe their intent was to specify a minimum...
