xian555
Specifier/Regulator
- Oct 30, 2014
- 6
Hello All,
In reading up on the subject over the last few months, including this posting on this forum, it has generated a number of questions.
The application is a lattice guy wire tower of 200ft, 3 faces, faces are 8ft centres, legs are tubular 6"OD HSS, lattice work are standard angle iron. Load is a small wind turbine of 65 ft OD, aprox. Applied standard is CSA S37-01 (similar to TIA-222), adapted to our use. Tower sections are 20ft each. The turbine load dead weight is about 10 tonnes, and we've design for a wind pressure of 600Pa (12.5 lbs/sq.ft, or a wind speed of about 70mph, with a gust factor of 1.6, or peak winds of about 111mph) and 1" of ice. Having read a study on remedial action on lot of communications tower that were over 50 years old, with innumerable other structures much older, we are attempting to design for a life cycle of 50 years.
My question is along the same lines as . In referring to Specification for Structural Joints using ASTM A325 or A490 Bolts - 2009 RCSC, page 91 of 100, Table B5.3. Allowable Stress for Fatigue Loading (attached), how do you get a handle on the number of cycles to use per year ? What of wind gust frequency and intensity ? For HSS round pipes, angle irons 350MPa (50ksi) steel, and, say A325 bolts, is there fatigue data that provides rate of fatigue versus % of maximum load ?
Thanks for any help, commentary, suggestions or information.
Best Regards,
Christian Martel, P. Eng. PMP
In reading up on the subject over the last few months, including this posting on this forum, it has generated a number of questions.
The application is a lattice guy wire tower of 200ft, 3 faces, faces are 8ft centres, legs are tubular 6"OD HSS, lattice work are standard angle iron. Load is a small wind turbine of 65 ft OD, aprox. Applied standard is CSA S37-01 (similar to TIA-222), adapted to our use. Tower sections are 20ft each. The turbine load dead weight is about 10 tonnes, and we've design for a wind pressure of 600Pa (12.5 lbs/sq.ft, or a wind speed of about 70mph, with a gust factor of 1.6, or peak winds of about 111mph) and 1" of ice. Having read a study on remedial action on lot of communications tower that were over 50 years old, with innumerable other structures much older, we are attempting to design for a life cycle of 50 years.
My question is along the same lines as . In referring to Specification for Structural Joints using ASTM A325 or A490 Bolts - 2009 RCSC, page 91 of 100, Table B5.3. Allowable Stress for Fatigue Loading (attached), how do you get a handle on the number of cycles to use per year ? What of wind gust frequency and intensity ? For HSS round pipes, angle irons 350MPa (50ksi) steel, and, say A325 bolts, is there fatigue data that provides rate of fatigue versus % of maximum load ?
Thanks for any help, commentary, suggestions or information.
Best Regards,
Christian Martel, P. Eng. PMP
