Footings & Load Factors
Footings & Load Factors
(OP)
I seem to come across an issue a lot that I don't know what to do with.
Often when checking bearing pressure under service loads I have no uplift across the footing. As soon as I factor my loads though I do get uplift.
In other words, the load factors change the structural support. The concrete design loads are now based on a an altered support condition influenced by load factors. This doesn't seem like a realistic approach to me. Any comments or thoughts?
Often when checking bearing pressure under service loads I have no uplift across the footing. As soon as I factor my loads though I do get uplift.
In other words, the load factors change the structural support. The concrete design loads are now based on a an altered support condition influenced by load factors. This doesn't seem like a realistic approach to me. Any comments or thoughts?






RE: Footings & Load Factors
RE: Footings & Load Factors
Adam Vakiener, P.E.
RE: Footings & Load Factors
RE: Footings & Load Factors
That approach seems a little conservative, but reasonable to me. Any other ideas anyone?
RE: Footings & Load Factors
i encountered a similar thing about tension load.
load combination was allowable.
tension reaction was say 20 kips.
another engineer's calcs, he multipied the tension to 1.6 to make it ultimate or factored.
RE: Footings & Load Factors
RE: Footings & Load Factors
That summarizes my question very well. Am I after the factored loads, or the factored load effects?
RE: Footings & Load Factors
RE: Footings & Load Factors
RE: Footings & Load Factors
RE: Footings & Load Factors
RE: Footings & Load Factors
RE: Footings & Load Factors
And I don't agree with simply multiplying unfactored bearing pressure by 1.6. This can be unconservative sometimes.
DaveAtkins
RE: Footings & Load Factors
RE: Footings & Load Factors
Also, you couldn't be looking for the factored load effects because you'd have a different support condition for dead, live, wind, etc. and you can't just find the effects of each one and add them together. You have to combine the loads somehow before you find the load effects.