Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Beam Stability Factor (CL) and Rb, lu, and le when material is laid flat.
- Thread starter Ron247
- Start date
Per NDS, yes, you need to consider the adjustment to design values as shown in table 4.3.1 of NDS. However, 3.3.3.1 indicates that is d <= b, then CL = 1.0. Since Rb and le are used for the CL calc, and we already have CL defined in code, we shouldn't need to consider their calculation. Be aware that Rb is a separate check that should be followed, but if you're installing anything in plank orientation, Rb per 3.3.3.6 should not be an issue.
- Thread starter
- #3
CL in the NDS is intended to address stability and prevent buckling and/or twisting out of plane due to high loads and a lack of restraint.
Similar to Steel and the Lb that affects section strength (i.e. limit allowable stress to a level below which buckling will not occur). As the LTB provisions in steel note, LTB is not a concern (it doesn't physically happen) when you are bending about the minor (weak) axis. Similar applies here to wood construction. ChorasDen is correct. (Side note, use 'cross' material references with caution, but it's supportive in this circumstance as the buckling is a physical phenomenon that is not specific to a material, the material design provisions change but the concept of preventing buckling remains).
Similar to Steel and the Lb that affects section strength (i.e. limit allowable stress to a level below which buckling will not occur). As the LTB provisions in steel note, LTB is not a concern (it doesn't physically happen) when you are bending about the minor (weak) axis. Similar applies here to wood construction. ChorasDen is correct. (Side note, use 'cross' material references with caution, but it's supportive in this circumstance as the buckling is a physical phenomenon that is not specific to a material, the material design provisions change but the concept of preventing buckling remains).
- Status
