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!

*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.

Jobs

Columns of A large roof-Effect of Snow load reducible?

Columns of A large roof-Effect of Snow load reducible?

(OP)
Pals

For Live loads, reduction is based on tributary areas for columns and girders. Which makes good sense.

I am curious, is snow load reduction possible for columns with very large tributaries? If not,what is the rationale for not reducing it?

respects
IJR

RE: Columns of A large roof-Effect of Snow load reducible?

2
If there is no wind, snow will fall on the whole roof evenly.

You should be asking what is the rationale for reducing it?

RE: Columns of A large roof-Effect of Snow load reducible?

Agree - snow simply falls and there is no statistical basis for snow NOT happening over large areas vs. small areas.

RE: Columns of A large roof-Effect of Snow load reducible?

In Canada... where 0.8 of the Ground Snow Load is typically used, for larger roofs, there is no 0.8 reduction to accommodate snow falling on the larger area.

Dik

RE: Columns of A large roof-Effect of Snow load reducible?

In Canada there is no tributary area reduction permitted for snow loads.  The rational for this not sure, I would presume the uncertainty in prediciting the load?

RE: Columns of A large roof-Effect of Snow load reducible?

Just thinking looked at ASCE 7-02 no tributary area reduction for snow either.  The reason is, I believe, is that for multiple floors the probability of all being loaded to full specified load simaltaneously is low, ie the permitted tributary area reduction for live load, however you only have one roof so no reduction.  I reduce the live load due to use and occupancy for a building with only one floor though.  Go figure.

RE: Columns of A large roof-Effect of Snow load reducible?

Next time it snows without wind go out and have a look around if there was 2" of snow there will be 2" everywhere it is flat and that there was not an obstruction.

same would apply if it was 3' and no wind.

Take a step back from the books for a reality check every now and then.

RE: Columns of A large roof-Effect of Snow load reducible?

your point csd72?  I think I've missed something?

RE: Columns of A large roof-Effect of Snow load reducible?

My point is that the snow load is uniform when there is no drift, this is a physical fact that can be observed in the real world regardless of code books.

RE: Columns of A large roof-Effect of Snow load reducible?

The other aspect of live load on a roof is that it is there primarily to accomodate the potential of maintenance workers on the roof, at least in a post-construction timeframe.  There is a good likelihood of a few workers congregated in one area, say around a roof top unit, but it is highly unlikely that you would ever have enough workers on the roof to require the small trib area level forces over a significantly large trib area.

RE: Columns of A large roof-Effect of Snow load reducible?

Thought we were talking about reduction of snow load based on tributary area?  In any case no reduction, based on tributary area, is permitted for structural members carrying snow load.  Makes sense.  Might have misunderstood the original question.  Snow drifts, Ive been shovelling them since the beginning of December, I far prefer snow without wind, rarely see it though.

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


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close