Up until now I have been using the "allowable" stress values shown in the NDS tables included in the Timber Frame Design book in my structural models.

I note that the values shown, for example, ultimate horizontal shear in the Wood Handbook are between 10 to 20 times higher.

I am currently working with a client who is required to use limit state analysis and this seems to permit allowable stresses to rise higher than NDS allowable.

Can anybody shed some light on this please ?

Regards
Ken Hume http://www.clik.to/WorldofWood

My experience has been that most limit analysis approaches use a higher allowable than the allowable stress approach, but use load factors on the other side of the equation. This would be similar to LRFD (load resistance factor design) in steel design. Although I am an engineer, I'm not the leading authority in this area; perhaps others can provide additional insight.