×
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

Assessment of Existing Buildings

Assessment of Existing Buildings

Assessment of Existing Buildings

(OP)

Dealing with a cantilevered street awning (tie-back through unreinforced brick parapet into return parapets at ends and into roof between), which are very common here in Australia. Client is replacing awning as it projects too far and trucks and caravans run into it. New awning is smaller(to eliminate chance of vehicular impact) and lighter (assessed uplift still not an issue).

Existing structure needs assessment as to its ability to carry new awning. Current issues under consideration --
1)Condition of existing fixings - will be replaced as required - no problem.
2)Weight and Plan area reduction of awning reduces "available" loading - reduces risk as compared to existing.
3) Reducing projection SIGNIFICANTLY reduces risk of failure, as any impact could of been its last.
4)Live Load requirements for street awnings has gone up significantly since original construction(from 0.25kPa to 1kPa) - although original is 40-50 years old and probably would not have been designed per se. This new demand is much greater than reduction from point 2). Current tie-back into roof system is in good condition but when load path is fully tracked, it lacks capacity to carry new live load.
5) Unreinforced brick parapet itself is a high risk item that have poor track record under lateral loading - retrofit while we can is my take.

Client is obviously doing the right thing by addressing point 3 above, yet are not so willing to pay for works addressing points 4 and 5.
Is there any regulations (I'm in Australia), that allow purely condition assessment and have provisions regarding allowable %change in loading, whereby upgrading is not required?
To clarify, if loading was to increase by say 5%, or in this case, load decreases slightly due to plan area reduction, then attention to condition is all that is required, as keeping structures up to date with every loading code change would not be practical.
In summary, without strengthening the supporting structure, but attention to its condition, the installation of this new awning reduces the risk to the public. On the other hand yet it is an opportune time to strengthen - which is my preference, client less so.

Any thoughts or experience on the matter greatly appreciated.

Toby

RE: Assessment of Existing Buildings

I'm in Canada, not Australia, but the premise is that when you take on the design of the element, you take on the responsibility. So, you're reducing the load & a hundred people will tell you "hey the other one worked, this is better, what's the big deal?" but I'd tell you lots of things have survived when they logically shouldn't have. Now that it's going to be hung around your neck do you really want that responsibility? I find unreinforced brick particularly problematic, having seen a couple buildings literally collapse. One was my problem, one wasn't and was a bit of schadenfreude because I had told the owner not to do the project & I refused to get involved. No one was hurt in either one, but...

RE: Assessment of Existing Buildings

(OP)
Thanks OldBldgGuy, appreciate your comments.
structure directly related to new awning is been strengthened to current requirements.
Anyone know of % change in capacity/loading rules here in Australia that waive any upgrading/strengthening requirements?

Toby

RE: Assessment of Existing Buildings

Appendix Z.3 of the Commentary to AS1170.4 has some guidance on this, I posted an extract a while ago on the AS/NZS forum - Link

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