Formulas for sizing timber moment
Formulas for sizing timber moment
(OP)
Hi -
I'm a geotech engineer so go easy on me with this one.
Having designed a tied-back retaining wall, I am trying to find a method whereby I can calulate the required timber pole moment for the horizontal waler that the tie-back tendons connect to - and thereby determine the minimum required pole size of that horizontal member. In this instance the uprights are at 1 metre centres and the tendon connects to the waler mid span (i.e. 0.5m from the upright either side of it).
Sketches are attached.
Sketch 1 is for a continuous horizontal beam (i.e. more than 1 tendon attached)
Sketch 2 is for a horizontal beam with only 1 tendon attachment.
Thanks in advance
I'm a geotech engineer so go easy on me with this one.
Having designed a tied-back retaining wall, I am trying to find a method whereby I can calulate the required timber pole moment for the horizontal waler that the tie-back tendons connect to - and thereby determine the minimum required pole size of that horizontal member. In this instance the uprights are at 1 metre centres and the tendon connects to the waler mid span (i.e. 0.5m from the upright either side of it).
Sketches are attached.
Sketch 1 is for a continuous horizontal beam (i.e. more than 1 tendon attached)
Sketch 2 is for a horizontal beam with only 1 tendon attachment.
Thanks in advance






RE: Formulas for sizing timber moment
I assume you in NZ, I think your local timber company can help. Carter halt Harvey have a program for engineers.
http://www.nceng.com.au/
"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."
RE: Formulas for sizing timber moment
If you conservatively assume the wale has a simple span between soldier beams, the moment M = PL/4. For a continuous wale with concentrate loads at the mid-spans, check AISC's 14th Edition (or earlier) Steel Constrruction Manual, page 3-212, which shows that Mmax = 0.171PL (5-span), 0.175PLK (3 span), or 0.187PL (2 span) with Vmax = 0.66P (5 span), 0.65P (3 span), or 0.69P (2 span).
www.PeirceEngineering.com