LRFD 2nd or 3rd Edition???????

[jarrettfan8875]

I have a question about the 1997 UBC and the LRFD code. The 1997 edition of the UBC references the 2nd edtion of the LRFD specification for use in steel design. My question is, since the 3rd edition is newer, is it acceptable to be used? When can the newer spec be used. I have talked to some, and they have said you can always use the newer code, altough others have said you can only used the code that is referenced.

My questions stems from the change that was made in the 2 codes regarding composite floor systems. In the 3rd edition, it states that for single row of shear studs in a rib perpindicular to the beam, that the max value for a reduction is 0.75, while the 2nd edition states 1.0 for a max.

i have read that this stems from newer testing that was done showing the 2nd edition was a little unconservative.

Obvisously, since i have knowledge of this, i need to design it correctly, but was just wondering in case there are other differences in the 2 codes. Does anyone know of a site that lists the difference in the 2 editions????

 

[JAE]

Don't know of a site showing the differences - but as far as "is it OK to use the newer code" I would say that the UBC code (or whatever model code) that is adopted by the governing agency/city is the minimum standard with which you must comply.

The governing code, in this case, references the 2nd Edition so you MUST meet the second edition. If a later edition allows a less conservative design, then technically you cannot take advantage of that as the governing body has not allowed that into the law.

If a later edition requires a MORE conservative design, then per your engineering judgement, you should use the more restrictive, later edition. This way, you still meet the requirements of the law, both technical and ethical.