Apologies in advance for the lengthy and boring post, but I'm pulling out my hair here.
We are working on the structural design of a monopole billboard sign in the Southern Nevada area under the 2006 IBC. The area has enough seismic activity to push the structure into seismic design category D. Even so, the wind loads are still approximately 6x greater than the seismic loads. Seismic loads were determined using the equivalent lateral force method with coefficients from ASCE 7-05 Table 15.4-2 for non-building structures not similar to buildings.
Because of the SDC, the plan reviewer is requesting/requiring that the structure be designed, detailed and fabricated in accordance with AISC 341 Part I per IBC section 2205.2.2. IMO, this seems excessive...but obviously there's not a section in the code that specifically exempts signs or billboards.
I'm looking for any code references to help backup my opinion. I honestly don't think it's the intent of the code. I'd like to say that 341 doesn't apply to non-building structures not similar to buildings, but the words "building" and "structure" are often used synonymously which makes that argument a stretch.
What I have found is the following:
1. IBC section 1604.10 states that even if wind governs lateral loading, seismic detailing requirements of the IBC and ASCE 7 must be met excluding ASCE chapter 14 and 11A. Section 14.1.3 is essentially the exact same section as IBC 2205.2.2 above. This exclusion and then re-inclusion in chapter 22 seems to contradict.
2. ASCE table 15.4-2 is blank under the "Detailing Requirements" column of the table. A blank section is designated to mean that no specific detailing requirements apply per note C.
3. (this one is really round-about) The most similar system in ASCE table 12.2-1 is (G) "Cantilevered Column Systems..." The detailing requirements in that table note ASCE chapter 14, which again per #1 above is specifically excluded when wind loads govern.
So, I guess my question is this: Does AISC 341 apply to a billboard structure which is in SDC D? A hard line reading of 2205.2.2 would say yes, but the examples above seem to say otherwise. What say you?
We are working on the structural design of a monopole billboard sign in the Southern Nevada area under the 2006 IBC. The area has enough seismic activity to push the structure into seismic design category D. Even so, the wind loads are still approximately 6x greater than the seismic loads. Seismic loads were determined using the equivalent lateral force method with coefficients from ASCE 7-05 Table 15.4-2 for non-building structures not similar to buildings.
Because of the SDC, the plan reviewer is requesting/requiring that the structure be designed, detailed and fabricated in accordance with AISC 341 Part I per IBC section 2205.2.2. IMO, this seems excessive...but obviously there's not a section in the code that specifically exempts signs or billboards.
I'm looking for any code references to help backup my opinion. I honestly don't think it's the intent of the code. I'd like to say that 341 doesn't apply to non-building structures not similar to buildings, but the words "building" and "structure" are often used synonymously which makes that argument a stretch.
What I have found is the following:
1. IBC section 1604.10 states that even if wind governs lateral loading, seismic detailing requirements of the IBC and ASCE 7 must be met excluding ASCE chapter 14 and 11A. Section 14.1.3 is essentially the exact same section as IBC 2205.2.2 above. This exclusion and then re-inclusion in chapter 22 seems to contradict.
2. ASCE table 15.4-2 is blank under the "Detailing Requirements" column of the table. A blank section is designated to mean that no specific detailing requirements apply per note C.
3. (this one is really round-about) The most similar system in ASCE table 12.2-1 is (G) "Cantilevered Column Systems..." The detailing requirements in that table note ASCE chapter 14, which again per #1 above is specifically excluded when wind loads govern.
So, I guess my question is this: Does AISC 341 apply to a billboard structure which is in SDC D? A hard line reading of 2205.2.2 would say yes, but the examples above seem to say otherwise. What say you?
