Seismic calc's. - Zone vs. Design Category question

[bsmet95]

My company designs and builds patented track underhung bridge cranes & runways, as well as underhung wire rope hoists. Occasionally a customer requires seismic calc's. for an installation. I have done calc's. for Zone 4 applications, but this customer specifies Design Category 3. A zone was not specified. I have found some info on Design Category. How does Design Category differ from Zone, and are there different calc's and acceleration factors used?

Thanks.

 

[hawkaz]

What code are you referring to? IBC now uses Design Categories A-F. Zones 1-4 was in the old UBC

 

[bsmet95]

Sorry, it's IBC.

 

[TehMightyEngineer]

So do you mean Seismic Design Category C?

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[sandman21]

They most likely meant risk category, see table 1604.5

 

[bsmet95]

Seismic Design Category C.

 

[spats]

I suggest you get with the program. I don't think zones have been used since UBC '97.

 

[bsmet95]

I will, gladly. What do I do with the design category?

 

[DaveAtkins]

I may be wrong, but it has always appeared to me that:
SDC A = Zone 1
SDC B = Zone 2
SDC C = Zone 3
SDC D, E, and F = Zone 4, depending on several different factors.

The approximation is rough.

DaveAtkins

 

[spats]

You get a copy of the applicable code, and you read it.

 

[ajh1]

SDC categories give you the rules for implementation, however you need to know the Ss and S1 values to actually be able to determine the seismic factor and thus the loads. Yes there is some correlation between SDC and zone as DaveAtkins mentioned, but it is not a one-to-one such that simply knowing the SDC will give you the seismic factor to use.

 

[bsmet95]

I've been searching for the code online. ICC.org has available, among many others, a 2015 Code and Commentary, Vol. 2, dealing with structural. Would this be a good buy?

 

[Gumpmaster]

Yes, that would be a good buy.

Most of the seismic information is in the ASCE 7 document though. I would recommend that you buy ASCE 7-10. The seismic loading methodology is quite a bit different than that in the UBC. There is a chapter on seismic loading of non-structural items such as cranes, although I don't think it addresses cranes directly.

 

[bsmet95]

Thanks for your help.