FHWA - Circular No4 Reese-Wang Eqns 1

[RFreund]

In Appendix A and Appendix B the Wang-Reese equations are used and shown in a spreadsheet format. I have 2 questions pertaining to the Passive resistance for sands spreadsheet in appendix B:

1. How is the Total Passive Force Calculated? I thought it was the d/2 (toe depth) x Min. Passive Resistance but I think I'm missing something.

2. They set d=h1 and alpha=0 in to solve eqn B-2. What is h1? I thought it might be the depth of toe below the excavation minus di, but I wasn't sure.

Thanks.

EIT

 

[jdonville]

RFreund,

I spent just a few moments looking at the Appendix in question, but here goes:

This is how I do it:
Select d.
Check to make sure that Ppu by Eq B-5 is more than Ppu by Eq B-2.
Compute Fp by Eq B-1, subtract Fp computed for d = di, b=0, if di > 0.
Check to make sure this value is less than that for a continuous wall.
For LRFD, factor and compare with the active earth FORCE.

The spreadsheet presented may be performing an integration over d to determine the total resistance.

Hope this helps.

J

 

[RFreund]

Thanks that does help. I think you might be right about the integration, that was my initial suspicion.
Atleast I can complete the spreadsheet now. We have some software and I made a different spreadsheet using the Cali Trenching and Shoring manual but I wanted to compare the results with this manual.

One question,
When you compute Fp with d=di and b=0 are you using Eq B-1?

Thanks


EIT

 

[jdonville]

Yes, the same Eqn.

J

 

[RFreund]

Thanks!

EIT

 

[piltomania]

hello, I hope not to bother, but the truth is I can not calculate the column ""Wedge Resistance d = h1, alpha = 0 (Eq. B-2)"" of the spreadsheet for the method of wang-reese.
the problem is that it is not h1, (h1 = d-d1 ?????), if the response does not give me the values shown in the example that appears in the document.
Thank you in advance for helping

Greetings
piltomania

 

[piltomania]

and solve the above problem

now I have problems with the column "Total Passive Force (WR)"
and I guess it must be calculated with Eq-B-1, but
values are not entirely reliable.
I would like someone to tell me if this equation is solved or
another, or must be supplemented with something special.
in advance thank you very much



piltomania

 

[RFreund]

I'll have to look into the calc because I was having similar issues. I've been busy lately and never finished my spreadsheet. Hopefully I can look at again this weekend.

EIT

 

[piltomania]

thanks RFreund

also know that eh had trouble figuring FACTOR SECURITY
WANG-REESE(SANDS), as I step by step example of the rule and not give me those results.
I think the safety factor should be calculated as:

FS = (Minimum Wang-Reese Passive Resistance) / (Rload)

where Rload = (Toe reaction)X(separation between profiles)

I hope your help

piltomania