×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Anyone written a Sprdsht to complete TR-55 Worksheets

Anyone written a Sprdsht to complete TR-55 Worksheets

Anyone written a Sprdsht to complete TR-55 Worksheets

(OP)
I'm in the process of creating an Excel spreadsheet for TR-55 Worksheets 2, 3 and 4 (Runoff CN, Time of Concentration and Peak Discharge, repspectively).  When done by hand, the process requires a lot of nomgraph input, which can be time consuming.  

I've been able to enter most of the formulas that solve the nomographs in the spreadsheet except for one of the last items needed on Worksheet 4, the Unit Peak Discharge (qu).  It's been a few years since college, so I'm not sure exactly how to solve for qu and I'm not sure I've entered the formula into Excel correctly.  The formula given in Appendix F of the TR-55 manual is:

    log(qu) = c0 + c1 log(tc)+ c2[log(tc)]^2

My Excel spreadsheet has:

    =LOG10(((J4)+(J5*LOG10(F5))+(J6*(LOG10(F5))^2)))

J4, J5 and J6 are the C constants and F5 is the Tc.  The formula is returning an answer, just not the right one according on the nomograph.  Part of my problem is solving the oringinal formula for qu.  Maybe I need a refresher in high school algebra.

Any help would be greatly appreciated.  Thanks

RE: Anyone written a Sprdsht to complete TR-55 Worksheets

Seems to me that-

If Log(qu)=f(Tc) then
10^(log(qu)) = qu = 10^(f(Tc))

because 10^x is the antilog, but your formula uses another LOG10, so try changing your first LOG10 to 10^

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources