Height limits for nonbuilding structures
Height limits for nonbuilding structures
(OP)
I have a nonbuilding structure that is similar to a bldg. As I look at ASCE7-05 in Table 15.4-1 at the Ordinary steel concentric braced frames I am limited in height to 35' for SDC=D. Just below I note "With permitted height increase" with lower R, Omega and Cd and a height limit of 160ft. My structure is 63' and not a pipe rack...where-oh-where do I find criteria for a "permitted height increase"? No luck in AISC341 or in the rest of 15.4. Thanks






RE: Height limits for nonbuilding structures
RE: Height limits for nonbuilding structures
RE: Height limits for nonbuilding structures
Just curious, why do you take I=1.5? Why not I=1.0? Is there any reason for that?
Thanks.
RE: Height limits for nonbuilding structures
1. Applicable reference document listed in Ch 23.
2. The largest value as selected from Table 11.5-1.
3. As specified elsewhere in chapter 15.
I didn't have any luck with 1 or 3 so I think I'm stuck with 2, thus the 1.5.
RE: Height limits for nonbuilding structures
Regarding 15.4.1.1, is your structure in occupancy category IV? I could perhaps understand III for power generation if that's where your coal is headed. Item (b) in 15.4.1.1 is oddly worded, but I don't think they intend for you to always select I=1.5 unless your structure is O.C. IV.
RE: Height limits for nonbuilding structures
RE: Height limits for nonbuilding structures
Regarding 15.4.1.1, I have the same feeling as azcats. I have seen a design calculation report of a grain storage hopper bin one or two years ago, in which, the designer (an SE) applied the ACSE7-05 table 1-1, and take the hopper bin as an Agricultural facilities, thus belong to O.C.I. I guess it's reasonable because Table 1-1 applies not only to buildings but also to "Other Structures".
Just my 2cents.
RE: Height limits for nonbuilding structures
if the hopper/bin is in a hospital, a police station, an emergency shelter, etc., then it belongs to O.C.IV.
if the hopper/bin is in a power generation station, a water treatment factory, a university, etc., then it belongs to O.C.III.
if the hopper/bin is in a farm, then no matter what content it has (coal, sand or grain), it belongs to O.C.I.
Please correct me if I am wrong.
Thanks.
RE: Height limits for nonbuilding structures
I'd say you are dead on and that is the approach that I settled with...
In my rush to get the thing done I took the ASCE text at face value...reading "largest value" and moving on. I simply hadn't considered the intent of the code.