IBC - Load combinations when uplift is present ?
IBC - Load combinations when uplift is present ?
(OP)
Hi,
I have a concrete beam on soil (expansive, uplift pressure)
Span = 30 feet (ends fixed)
if My loadings are (plf - pouds per linear feet):
WLu = 1500 plf (uplift load)
WL = 500 plf (live load - gravity)
WD = 600 plf
What if the load combination and what will be the factored linear load (LRFD) ?
Because I understand that the live load will counter some force of the uplift, meaning that WLu = (1500-500) = 1000 uplift
I have a concrete beam on soil (expansive, uplift pressure)
Span = 30 feet (ends fixed)
if My loadings are (plf - pouds per linear feet):
WLu = 1500 plf (uplift load)
WL = 500 plf (live load - gravity)
WD = 600 plf
What if the load combination and what will be the factored linear load (LRFD) ?
Because I understand that the live load will counter some force of the uplift, meaning that WLu = (1500-500) = 1000 uplift






RE: IBC - Load combinations when uplift is present ?
RE: IBC - Load combinations when uplift is present ?
I've not ever designed for actual soil uplift (swell from expansive clays) before. I don't know how you can quantify it that exactly. Usually for expansive clays you try to avoid soil contact (crawlspace, etc.).
RE: IBC - Load combinations when uplift is present ?
RE: IBC - Load combinations when uplift is present ?
RE: IBC - Load combinations when uplift is present ?
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: IBC - Load combinations when uplift is present ?
RE: IBC - Load combinations when uplift is present ?
I designed a post-tensioned slab on grade in Texas and recall that you are not designing for a force as much as you are designing for a movement. Consider the soil expansion to be similar to thermal movement and detail to allow the movement rather than trying to resist it.
RE: IBC - Load combinations when uplift is present ?
Design considers that expansion pressures exist, but not necessarily in quantifiable form, so separation as Mike and JAE have noted is appropriate for design.