ASCE7-10 - Table 12.2.-1 - Issue

[krus1972]

Table 12-2-1 Page 60 of the ASCE7-10 Standard, under "Building Frame Systems". Looking at "Steel Ordinary Concentrically Braced Frames", Seismic Design Category "D".

It lists "35" with an "j".

Footnote "j" explains that these frames can be used up to a height of 60 ft where the dead load of the roof doesn't exceed 20 psf.

1.) Does this mean there are no restrictions between a height of 0 - 35 ft and a 20 psf roof dead load restriction between 35 - 60 ft?

2.) Or, does this mean the 20 psf dead load restriction applies to all any height up to 60 ft?

It seems to me, that #1 above is the correct interpretation. If #2 was the correct interpretation, the table would list "NP" with the "j" footnote.

I would like other, experienced peoples' interruption of this.

Can someone tell me, where within the code, they explain the proper interpretation of this table?

Thanks for your help

 

[JAE]

I would see it as this:

1. ALL buildings with SOCBF systems in SDC D are limited to 35 ft. height.
2. HOWEVER, if your building:

a. Is single story, and​

b. Roof dead load <= 20 psf, then​

you can go to 60 ft.

So your option 1.

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[MrHershey]

I also vote option 1, and echo JAE's clarification that footnote j limits it to *single story* buildings up to 60 feet tall with roof dead load not exceeding 20 psf.

 

[OUe]

I believe the intent is for hangar type structures. Also, metal building companies usually don't have multi-story applications and it was written for them. Just my $0.02.