×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

What ap/Rp would you use for a suspended catwalk with lateral bracing?

What ap/Rp would you use for a suspended catwalk with lateral bracing?

What ap/Rp would you use for a suspended catwalk with lateral bracing?

(OP)
The catwalk is suspended from a steel structure with tube hangers with lateral bracing at about 7'-6" above the catwalk elevation.

Catwalk will have C6x stringers at 5'-0" o.c. with 1/4" diamond steel plate and L2x2 @ 30"o.c.

Code = ASCE 7-05.

Previous engineer used a ratio of 1/2.5.. I am thinking this is more of a flexible component with high deformability and use 2.5 / 3.5.
I believe the fundamental period of the braced structure needs to be less than 0.07 seconds to be considered "rigid" and I don't think this layout would be rigid, therefore and ap value of 1.0 may not be appropriate.

I would prefer tho to use the lower coefficient and let this element be very flexible as deflection isn't really an issue. So I am torn...ponder

RE: What ap/Rp would you use for a suspended catwalk with lateral bracing?

(OP)
Any seismic engineers out there?

RE: What ap/Rp would you use for a suspended catwalk with lateral bracing?

this is an engineering judgement call....it being a suspended walkway, the issue of safety would influence my decision and would tend to go with the more consevative value...anyway, the difference between the two values is not that significant....I certainly would pay special attention to the connection of the walkway to the main structure...

RE: What ap/Rp would you use for a suspended catwalk with lateral bracing?

I might be inclined to be even more conservative. The catwalk is hanging with a brace half way between the catwalk deck and the structure above. I might use ap=2.5 and Rp=2.5 (or shave down the load a little by using ap=2.5 and Rp=2.5 for everything below the brace and ap=1 and Rp=2.5 for everything at the brace and above). Perhaps I am too conservative, but it may act similar to other things in the table with the same factors (cantilevered elements, appendages, and signs). Maybe, ap=2.5 and Rp=3.5 is a good compromise. But, how much cost is added with the more conservative loading.

I don't know what your loads are. But assume Fp=2Wp, Wp=100 plf and brace spacing at 40', the horizontal force is only 8 kips. That is less than 12 kips axial load into the HSS 4x4 brace.

RE: What ap/Rp would you use for a suspended catwalk with lateral bracing?

Oopps - double the brace force because it is half way up the hanger.

RE: What ap/Rp would you use for a suspended catwalk with lateral bracing?

(OP)
Thank you guys for the response. I agree I will use a higher design load.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources