How exactly should the vertical component of LL surcharge on the footing be input?
I have a 100 ft long footing (x dir) with a 9.75 ft heel (z dir). Per AASHTO, I'm using the equivalent of 2 ft of soil for the surcharge. There's 80 ft of clear roadway width centered on the abutment & footing.
Is the UDL = 2' x 9.25' (heel) x -0.125 ksf = -2.31 kip (per linear foot along length of footing), or something else?
And what should the inputs be for "y1/L-x1/L-z1/L" and "y2/L-x2/L-z2/L"?
I only want the LS distributed over the heel.
Also, is this vertical LS load able to be displayed under the "Geometry" tab -> "View Loads"? I can only get the horizontal component of the LS to display.
Thank you.
Vinay,
Did you mean to say that "The program will apply this load in the Y direction and only on the heel of the footing"?
When I input the load as described I was expecting to see rather uniform footing pressures at both toe corners and heel corners as was the result without this vertical component of LS added in. When the vertical component of LS is added in the results are no longer consistent leading me to think the load is not applied across the entire 100 ft length of the footing. Can you help me understand this? Thank you.
Without Vertical component of LS added:
With Vertical component of LS added:
I'm confused about the limits of the application of the load. I only want the load applied to the heel (9.25' heel / 18' total ftg), but want it applied the entire 100 ft length of the footing. I highlighted a snip from the Help menu. It states that "L" is footing length along the x direction. In my situation that's the 100 ft length, not the heel dimension.
If I input y2/L-x2/L-z2/L as 1.00, I get more uniform results but am not sure that the load is only being applied to the heel of the footing:
There might me typo error in the help file on what exactly L means.
To make it clear I selected EV load case which is Vertical Pressure from Dead Load of Earth fill.I clicked Edit and applied vertical soil pressure along the length of the footing.Footing Number = 1 Load Type = UDL Direction = Y Mag = -10 k/ft y1/L-x1/L-z1/L = 0.00 y2/L-x2/L-z2/L= 1.00
If you want to apply only at back of the abutment then y2/L-x2/L-z2/L= 0.5
In the attached screenshot it is clearly shown that the vertical UDL is applied in Z direction .
Same concept is applied for LS load case and if you want to apply the LS load on heel of the footing then
y1/L-x1/L-z1/L = 0.00 y2/L-x2/L-z2/L= 0.513 (0 - 9.25 ft )