Need some clarification on Caesar II Soil Modeler : American Lifelines Alliance

dP = Yield Displacement Factor, Lat.
"F1" returns a formula dP = 0.04(H+D/2)

Upon calculation the answer is much higher than recommended typical entry between 0.1 and 0.15

Also,in the user's manual the formula is shown as 0.4(H+D/2) that would return a even higher number.

Has anyone encountered this and can advise the correct input?

Yes, the ALA document says dP=0.04(H+D/2) but there's a little more to it:
dP=0.04(H+D/2)<0.10D to 0.15D.

And your input is a multiple of D.

If H=3D (not uncommon?), dP=0.04(3D+D/2)=0.14D

Thanks Dave,
May I request you to also clarify the following:

The "Virtual Anchor Length" as reported on Buried Pipe Data by Caesar :
Is it the length from elbow to virtual anchor ? or the length between two virtual anchors on same run of pipe ?

The virtual anchor length (VAL) is not a fixed point. The VAL is the distance from the point under consideration, past which the pipe behaves as if anchored. If you consider a different point in the model, the VAL is considered from that point.

Just to add a little more...

If a piece of pipe is anchored on both sides, the load on the anchors can be calculated based on the thermal strain and response to pressure load (end cap pressure and Poisson shrinkage). Except for boundary conditions (like an imposed deflection on one end or the other), there is no other load acting on the pipe.
If I have a long run of buried pipe, the axial friction between pipe & soil will resist this (constant, thermal & pressure) load. The axial friction load will balance this constant load if there is a sufficient length of pipe to do so, this is that VAL. If the amount of straight pipe - both upstream and downstream of a point (that's 2 times VAL) - that point is "locked in" or "fully restrained" and that point can be evaluated without any regard for anything happening upstream or downstream. You could say that this section of pipe can be isolated from the rest of the system. Actually, this section need not be evaluated by CAESAR II since the stress is identical to that pipe between two anchors - a simple hand calculation will do.
Now, what if I have a elbow or tee "near" my point of interest? The (assumed) perpendicular pipe serves as an additional axial restraint for the point in question. This will reduce the required (friction) length of pipe needed to balance the self-load (caused by T&P).
But I have to consider both upstream and down stream and I think this is where things get confusing. Instead of selecting an arbitrary point along the buried line, focus on these thrust points (elbows, tees, thrust blocks). Each thrust point associated with bends and tees will have a leg that pushes the pipe off its axis, causing bending stress and that's what we are interested in. If I can go upstream and downstream from these points, one VAL each way, without crossing another thrust point, this local subsystem is isolated from the rest of the system and can be analyzed without the other pipe. But you run into another thrust point within that VAL, you should model that section too and again search another VAL of pipe for the next thrust point.

I'm a little confused on this multiple of D and H concept. I'm trying to better understand the ALA method in order to run more accurate analysis, but I can't quite seem to grasp it.

We commonly work with 24" pipelines, and have a buried depth of 5ft. So proceeding with the dP formula I get dP=1.2D which is outside of the typical range. Is this acceptable or will ALA only work within that range?

Also, when I get down to dQu, I don't understand the multiple of H and D referred to in the User's Guide. The guide states
dQu=MIN (MULTIPLE OF H)*H, (MULTIPLE OF D)*D
I don't understand what it means when it says "The maximum multiple of the pipe buried depth (H) must be entered here".

ALA Appendix B shows this lateral equation/inequality for dP:
dP=0.04[H+(D/2)]<0.10D to 0.15D
The program will use 0.04[H=(D/2)] but it will not exceed xD where you provide this x in the soil definition. (Hint: x would typically be 0.1 or 0.15)
Note too, that H in ALA is to pipe center while in CAESAR II, H is to top of pipe.
The Help explains this.
Regarding vertical uplift - here too, ALA gives:
dQu=0.01H to 0.02H for dense to loose sands <0.1D
The CAESAR II input asks you to set the multipliers for both H and D. Let's call these multipliers x & y as in xH and yD. CAESAR II will set dQu as the smaller of xH & yD.

Dear Dave,

I am doing stress analysis of buried piping by using ALA soil model.

My H & D values are as follows.

H=1900
D=273

dP=0.04[H+(D/2)] = .3D

my dp values are exceeding from the the typical values .1D to .15D

Can I use .3 in the soil definition.

Thanks,
Asif
Worleyparsons
KSA

CAESAR II soil input holds a limit for dP based on a multiple of the pipe diameter - typically 01. to 0.15 according to ALA. Te program will calculate dP using the equation you show but limit it o your D multiplier here.
If you want to get all the way to 0.3D, then enter 0.3 as your D multiplier.

Thanks Dave