Vertical Seismic Load Component. 1

[jetboat]

In load combinations E = ^Ev + ^Eh. All our designs have been Cat. A so per code i've been able to ignore the ^Ev values. Per the inspector we are required to design as a Category B for this particualr site. Per ASCE 2005 12.4.2.3 the ^Ev value is accounted for in the factor on DL. My question is ^Ev really a verticle load and if so How would you distribute this vertical component on each level/column? Or, is this ^Ev additive to the ^Eh value?

 

[JAE]

Ev is a vertical load. Any time there is an "E" in a load combination, that E includes both vertical and horizontal seismic loads.

So the Ev portion of the E could be included as a factor on your D load in a computer program load combination....such as 1.34D where it might be 1.2D (gravity) plus 0.14D (for Ev).

Also include it upward as well so you would also have a 1.06D (1.2D minus .14D).

 

[JoshPlumSE]

I have one minor disagreement with JAE. Yes, you should include Ev as an upwards load. But, this shouldn't normally be a part of the 1.2DL case, but with the 0.9 DL cases.

It certainly doesn't hurt to run the 1.2D - 0.14D (from Ev) case, but I cannot ever see it controlling.

Josh

 

[GalileoG]

I am curious as to why the NBCC does not consider vertical seismic load...

Clansman

If a builder has built a house for a man and has not made his work sound, and the house which he has built has fallen down and so caused the death of the householder, that builder shall be put to death." Code of Hammurabi, c.2040 B.C.

 

[JAE]

JoshPlum - I agree, good point - 0.9D case should be used with the upward seismic effect.