Mistakes in the newly arrived AS3600-2018

[NTCONLINE]

Dear all,

Have you had any chance to look at the new arrival of AS3600?

I am quite impressed with the significant changes in the new standard.
It looks like the philosophy of design has changed. The long-debated ambiguous torsional reinforcement design in the previous code has been clearly improved. However, so far, I've found a number of mistakes:

1. Page 111, CL 8.1.5: "M*>0.08phiMuo" I guess it should be 0.8 instead of 0.08
(The previous code version 2008 used 0.6)
2. Page 116, CL 8.2.3.4 all equations 8.2.3.4(1-3) the units of the left-hand side and the right one of each equation does not match. Something is not right in those equations. I am quite concerned.

3. Page 121, CL 8.2.7 (a) and (b)
The term (|Veq*| - 0.5phiVus - gammaPv)^2 in equation (a)
but without ^2 in equation (b). This inconsistency triggers me to question whether it's correct

I will update this threads as I go on checking the new code. But your opinions and any other mistakes if you can report would be appreciated.

NTC

 

[Trenno]

Not currently working with AS3600 so can't help much, but you'll find a few previous of threads about the new code here. This post may get more traffic in that sub forum too.

Link

 

[Settingsun]

I would say you are right about item 1. The draft version dated 17/8/2017 had 0.8 instead of 0.08. The 9/3/2018 draft had the 0.08 number.

Item 2: The right-hand side is meant to be divided by (bv*dv) in each case. That was the case in the 9/3/2018 draft and makes sense. Eg if torsion is zero, it reduces to V*<phi.Vu,max.

Item 3: I'm not too sure as I haven't looked in detail but looks like the square root shouldn't be in the second equation.

 

[rapt]

There will be an amendment shortly.

1 In this clause, The phrase beginning "and where....." was supposed to have been removed completely.

2 Is on the list to fix.

3 Is on the list to fix.

I will not say any more except to suggest that there are many more and you should not use the 2108 code until the amendment is released!

PS as suggested above there is an AS/NZS code forum that this should have been posted on.

 

[NTCONLINE]

Rapt, do you have any estimated date for the amendments?

 

[rapt]

When they are agreed to!

 

[Settingsun]

Will the 2018 code get a commentary? If so, is there a timetable?

 

[rapt]

Yes. No, but it will not be 5 - 13 years like last time!

 

[QSIIN]

RAPT,

As the first amendment has now been released, have the critical errors been addressed? Do you think it is now acceptable to adopt the 2018 code, or are there further amendments being worked on in the background?

 

[rapt]

QSIN,

There will be a more amendments coming during this year along with a Commentary hopefully. Because of Standards rules, some of the required changes are regarded as revisions and not amendments so need to go through more processes. Some of those are still critical, especially regarding Shear (both flexural and longitudinal) and Steel Fibre.

The 2018 code is still not referenced by BCA!

 

[IDS]

I am putting this question here, rather than in the recent thread in the Australian Standards forum, because it applies to design work under any code, especially where there are two separate levels of design code applicable to a structure.

Suppose there was a hypothetical large building structure that had significant failure of concrete elements associated with shear cracking. Suppose that design and construction were completed under one set of code requirements, but before the building was completed a new building structures code was issued, but not yet called up in the applicable building regulations.

Suppose it was found that the shear design complied with all requirements of the earlier code, but did not comply with the requirements of the new code.

What effect, if any, would this have on the liability of the building structural designer, when assigning costs associated with rectification of the structure?

What if the design complied with simplified provisions in the new code, but not with more rigorous provisions? Would that be sufficient to relieve the designer of any responsibility?

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[Settingsun]

Hi Doug (IDS),
The extent of my knowledge come from 'Contract Training for Project Managers' training at my current and past two employers - all gave fairly similar advice. I understand that it will have a lot to do with the contract the designer signed up to. Most client contracts try to raise the standard of care by various means, eg fit for purpose; expert standard; highest standard etc. All three of those companies would sign up to those terms only for juicy projects, preferably (or only) for state/federal government clients. Private clients and local councils were generally seen as too risky. At the most cautious company, we were given a list of words/phrases that were never to be used in proposals (ensure, guarantee, best practice, world-leading etc).

If only the default standard of care is required, compliance with the older code would be sufficient in an ideal world. If the standard of care were raised, it could be expected that the latest research (or foreign codes, or the bridge code) would be used in the design. If fit-for-purpose was required and was the basis for the law suit, the designer's insurer might be off the hook as I understand it's hard or too expensive for engineering consultants to get that cover. That could put even a large consultant out of business.

In the real world, it's often down to the PI insurer to decide whether to settle rather than fight at potentially greater cost.

 

[rapt]

Doug,

My understanding from engineering "ethics" lectures a long time ago, was that if the designer knows or if it is common knowledge that a design method in a code is questionable/wrong then it is his/her responsibility to ensure that the correct method is used.

RE your specific point regarding shear design, I do not think that the old AS3600 requirements were bad enough to cause the sort of problem that you are referring to. Similar rules have been used since the 1960's (old BS8110) and 1970's and 1980's (AS1480/81 and AS3600) and also ACI318 without any problems that I know of. Ignoring rules (punching shear does not happen from earlier post) and bad detailing both in design and construction would cause a lot more problems and design codes cannot control how that is done in practice, only give rules.

 

[QSIIN]

I think I remember reading the new NCC will be revised around April/May 2019...? Don't quote me on that though. Potentially it will be referencing the new 3600 before the next amendment is released..?

 

[NTCONLINE]

Amendment 1 has come out since last week.

 

[rapt]

It came out in November. But I have not mentioned it as it is not complete. There will be a much larger amendment/revision later this year.

 

[NTCONLINE]

hi RAPT,
is it worth doing a design with the current AS3600-2018 amendment 1, or just wait?
Do you know whether the coming Build Code will enforce the use of this AS3600-2018 in May?