Contact US

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!

*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

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

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:


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! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close