Using moment directly from FEA for slab design

[GalileoG]

I recently discovered a code equation in CSA A23.3 04 that goes something like this: Mx + |Mxy| which is intended to be used to account for torsion on your moments for two-way slabs. In other words, you can not use the moment that is given by the FEA software without magnifying it for torsional effect. I have never known about this clause until today and a colleague of mine said that the torsional effect on two-way slabs can be significant (raising moment by up to 20%)

I was curious to see if such a clause exists in ACI and if you folks usually take it into consideration when designing two-way slabs.

Thanks,

Clansman

 

[sdz]

Something similar was discussed in

http://www.eng-tips.com/viewthread.cfm?qid=233588&page=9

See if that helps.

 

[oneintheeye]

no you can't, unless it gives wood and armour moments. I believe

 

[JAE]

Clansman - this isn't a code issue - it is simply using the correct moment from an analysis. The combination of Mx + Mxy and of My + Mxy in each direction is the correct "total" moment to use in determining reinforcement.