Seismic design for catwalk

[htennek]

I am working on a catwalk design project in California. I am trying to find how to calculate the base shear for the structure. I ran through ASCE7-05 and IBC 2006 but I could not find a seismic design section talk about catwalk/bridge. I think the catwalk should fall between building structure and non-building structure. Please help.
Thanks

 

[civilperson]

If braced frame then building. if cantilever columns then non-building.

 

[msquared48]

In the older codes, this would fall under "Parts of a Structure" and be subjected to 30% of it's weight seimically. I would have to check out the IBC for the applicable section now.

FYI: You would get more suggestions here if you posted under the "Structural Engineering Other Topics" section of the forum.

Mike McCann
MMC Engineering

 

[kslee1000]

Mike:

Is the terminology "Structural Components" sounds right for
"Parts of a Structure"? Just curious.

 

[htennek]

Thanks for the reply. My catwalk platform is supporting by series of steel columns w/ X steel braces in between. If the catwalk structure is defined as building structure, then I can use the equations in ASCE7 Chapter 12. For those coeffs within the equations, can I use Ct = .028, x = 0.8, R = 3.5?

 

[msquared48]

Check the errata definition revision in Chapter 13, section 13.1.1, which sets out a limit between structural and non-structural component analysis requirements.

The addition in the errata states: "Where the weight of a non-structural component is greater than or equal to 25% of the effective seismic weight, W, of the structure as defined in section 12.7.2, the component shall be classified as a non-building structure and shall be designed in accordance with Section 15.3.2."

Mike McCann
MMC Engineering