×
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

Lateral bracing of bridge girders
4

Lateral bracing of bridge girders

Lateral bracing of bridge girders

(OP)
Can anybody give me guidence (or suggest any book)  for design of lateral (wind) bracing of bridge girders.How we can incorporate/add wind load in to the load calculations during construction i.e before placement of concrete deck?

RE: Lateral bracing of bridge girders

This looks like the same horizontal deflection question for bridges that was asked and answered.  ASCE 7 has the wind forces and judgement can lower these forces if shielding or sheltering of interior girders apply.  I use no deduction from full wind on each girder when spaced 3 times the height apart.

RE: Lateral bracing of bridge girders

You can design the bracing system as though it were a truss. I assume you checked AASHTO to see if bracing is needed.

If this is LRFD you have to perform the calculation for bracing the compression flange during construction. If you're using the Standard Specs no check for construction conditions is required. However, there are methods you could use. For instance, check the girder about the weak axis assuming the diaphragms act as a support.

The old old US Steel bridge design manuals had an example.

RE: Lateral bracing of bridge girders

I was asked to check flange bending stresses during construction on a job for Florida DOT due to a "reduced wind load" of ~50% x 50 psf if memory serves.

I multiplied the 50 psf x half the girder height to get a plf load on each flange.  Then I analyzed the flange as a simply supported beam and checked the stress.  I believe I divided the load by the number of gitrders in the transverse section since all girders would participate, although that may not be the case since there may only be 2 girders up when the big wind storm comes along.

Anyway, this is a method for determining a good minimum width for a flange to avoid problems during construction.  Good Luck.  Oh, I'd ask your boss.  He has a better understanding of what your client wants.

RE: Lateral bracing of bridge girders

You can find a wind bracing example in the AISC Highway Bridges Design Guidelines.  Check out AISC's website

Regards,
Qshake
pipe
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

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