1802.1 just says that allowable pressures shall be used with allowable stress design load combos.
Though I haven't yet had a geotech provide ultimate values, there is precedent for using them for foundation at least in ASCE7-22 12.13.5. Granted this section is in reference to seismic loading...
Also your model has slip at one end and I would be looking to detail it that way or investigate the consequences of locking it in.
I like the idea of a simple shear tab on the top chord and potentially another shear tab at the bottom chord perhaps with slotted holes.
The slab needs to serve the role of drag strut collector. Some assessment of the tension and compression capacity of the slab as a strut/tie needs to be performed. There are different approaches used, some add supplemental reinforcement while others use the slab distributed reinforcement over a...
It is odd that you are saying gravity loads cause lateral deflections. The only reasons I can think of that that would happen are if you have a lot of P-delta or If your lateral system supports dead load (thrust typically from non-vertical gravity load resisting elements).
First I think you...
While I agree with your conclusion, I'd like to make a somewhat nuanced distinction on your response...
"I think an inverted pendulum is a special case of a cantilevered column system" - No its just a slender cantilever structure with more than 50% of the mass concentrated at the top.
Inverted...
If the source of lateral resistance is single columns bending about a fixed base you should use special detailing for cantilevered columns in my opinion. I do not believe that inverted pendulum and cantilever column systems are mutually exclusive.
I agree special foundation detailing and overstrength requirements are applied to cantilever column structures, and no such provision is written for inverted pendulum structures. I would refer to section 11.2 to verify that your structure doesn't qualify as a cantilever column system. By my...
Some internal QA/QC is needed on your end before you can address the issue.
A good free body diagram of the forces coming into the joint should give you the answers you need.
The baseplate needs to transfer all of the member forces to the foundation. There shouldnt be a 'huge' force that you...
I think this is the key thing for the OP. You need shear resistance, but can you tolerate some movement at the support in the design event.
If the shear is only for EQ that makes sense, if its for some other types of loading maybe not.
The Fpx is based on the inertial forces from that diaphragm level. The transfer forces don't show up in that as we calculate both Fx and Fpx by each diaphragm level and do not include any contribution for forces from above.
Basically the procedure is set up assuming that the inertial force is...
After reading Pham's reply alongside mine I think a sketch is useful
The first sketch shows what I was saying about full length collector, full depth load application. For a 2d diaphragm model, this is the same thing as a point load.
Second case shows what I think you were proposing as an...
