Base Shear Resistance for Ground Supported Tank
Base Shear Resistance for Ground Supported Tank
(OP)
Hey Everyone,
I have a ground supported steel tank that I am designing foundations for. The tank will be welded down to embed plates (of my design) placed into a large mat slab. For anchorage I planned on designing the embed for any uplift resulting from overturning from seismic or wind. For shear my plan was to count on the friction between the embed and the concrete. I've seen discussion on on this topic as it relates to columns baseplates and it seems there were a fair amount of opinion to NOT use friction for shear resistance.
Considering all load combinations and including the vertical shear force (reducing the gravity load) it seems reasonable to assume the down loads on my embeds could be counted for friction. When all is said and done I get a unity check of around U=0.4 for base shear/friction resistance.
Given the case would you have any issues counting on friction for shear resistance?
Thanks in advance!
I have a ground supported steel tank that I am designing foundations for. The tank will be welded down to embed plates (of my design) placed into a large mat slab. For anchorage I planned on designing the embed for any uplift resulting from overturning from seismic or wind. For shear my plan was to count on the friction between the embed and the concrete. I've seen discussion on on this topic as it relates to columns baseplates and it seems there were a fair amount of opinion to NOT use friction for shear resistance.
Considering all load combinations and including the vertical shear force (reducing the gravity load) it seems reasonable to assume the down loads on my embeds could be counted for friction. When all is said and done I get a unity check of around U=0.4 for base shear/friction resistance.
Given the case would you have any issues counting on friction for shear resistance?
Thanks in advance!






RE: Base Shear Resistance for Ground Supported Tank
RE: Base Shear Resistance for Ground Supported Tank
RE: Base Shear Resistance for Ground Supported Tank
RE: Base Shear Resistance for Ground Supported Tank
Not sure of your detail intention, but note that the chime of a normal tank isn't designed for uplift.
RE: Base Shear Resistance for Ground Supported Tank
RE: Base Shear Resistance for Ground Supported Tank
RE: Base Shear Resistance for Ground Supported Tank
15.7.6.1.5 Sliding Resistance The transfer of the total
lateral shear force between the tank or vessel and the
subgrade shall be considered:
a. For unanchored flat bottom steel tanks, the overall
horizontal seismic shear force is permitted to be
resisted by friction between the tank bottom and
the foundation or subgrade. Unanchored storage
tanks shall be designed such that sliding will not
occur where the tank is full of stored product. The
maximum calculated seismic base shear, V, shall
not exceed
V < W tan 30° (15.7-14)
W shall be determined using the effective seismic
weight of the tank, roof, and contents after reduc-tion
for coincident vertical earthquake. Lower
values of the friction factor shall be used if the
design of the tank bottom to supporting foundation
does not justify the friction value above (e.g., leak
detection membrane beneath the bottom with a
lower friction factor, smooth bottoms, etc.).
Alternatively, the friction factor is permitted to
be determined by testing in accordance with
Section 11.1.4.
b. No additional lateral anchorage is required for
anchored steel tanks designed in accordance with
reference documents.
c. The lateral shear transfer behavior for special
tank configurations (e.g., shovel bottoms, highly
crowned tank bottoms, tanks on grillage) can
be unique and are beyond the scope of this
standard.
RE: Base Shear Resistance for Ground Supported Tank
RE: Base Shear Resistance for Ground Supported Tank