We had a large, 6 storey building project, all masonry, a few years back. It was the first project with the 2018 code adopted, as the contractor heard about the new capacities and wanted to take advantage of it. We explained the limitations, needing BlockAid or similar etc. The contractor was...
Hi All,
I know this topic has been beaten to death on here, and no conclusion has really been made to clearly define the difference between a 'wall' and a 'column'.
The most current AS3600-18 Amdt 2 has definitely made steps in the right direction, but ultimately, engineers can, and are, still...
yeah, i guess so., which will probably be the case for most 'true' raft slabs, and the spans aren't really between each individual column/wall/core, but the entire raft dishing under the load. I think that the flexural tension demands can be reduced by 0.77/2, but shear would need to be designed...
Hi lion,
This is obviously going to need to be investigated on a case by case basis, but I'd think even if you have combined lateral systems landing on a shared raft, often the compression side of one element is going to be counteracting the tension side of another, unless all the elements are...
Hi rscassar
Some will tell you that the paragraph under table 14.3 is the answer - the least ductile element in the combined system governs the whole system.
However I feel this is more applicable for a building that has say a full-height core box and a full height shear wall/moment frame. The...
Sorry. I don't know how to quote text so this is directed at several previous messages..
My interpretation of the simplified approach to seismic design in Australia, is that if we ever get the 1/500 or 1/1000 seismic event, you're not repairing the structure afterwards. You're demolishing it...
The base shear in the structure is the same as the base shear on the raft - a horizontal shear (in-plane for the wall). This shear needs to be amplified (CL14.6.6) for the wall design and wall-raft base connection. But the horizontal shear probably doesn't need to be considered in the raft...
Again, the ductility approach is very crude and basic. We're basically reducing all tension steel requirements by 2.6, assuming the bars are all yielding how we expect them to, where we expect them too. Unfortunately, we usually put more steel in than required, we have material reduction...
I would think that the raft footing only needs to be designed, flexurally, for the same level of ductility provided to the primary lateral elements (core, shear wall etc) as it is part of the same ductile load path. For shear, the footing should be designed for overstrength, eg x2/0.77.
The...
As per others' comments, I would think that central dowels are acceptable, but you must have the same or more tension steel as required in the wall, to achieve the level of ductility you are designing for, and the dowels should be concentrated at your critical tension zone, to ensure the tension...
And yet there are numerous posts trying to clarify the new code requirements. I've had discussions with others from multiple design firms about similar issues. If only there was a way for practicing engineers to get in contact with the committee directly about these issues, but of course, the...
Thanks everyone for input.
Yes, my thoughts were when the code says "exceeds 0.15f'c anywhere in THE wall" it's still referring to the wall with discontinuous ends.
I'm still confused by CL11.7.4 (a): "for all walls in structures with a structural ductility Mu greater than 1.0, the vertical...
Hi there
Can anyone confirm that CL14.6.2 only applies to isolated shear walls with "discontinuous edges", and does not apply to walls within a closed core box?
I find that CL14.6.2.3 is quite onerous that where stress exceeds 0.15f'c, all verticals bars needing restraint. But then in a...
rscassar, yes it completely makes sense to amplify the shear forces. Unfortunately, I (like most others) were taught the static EQ loads calc from AS1170.4 with no thought to what Mu and Sp were actually doing. I know its not common, if done at all, but I was wondering if any engineers have...
Hi there
Has anyone ever specified, seen, or heard of projects utilising diagonally reinforced concrete coupling beams in Australia? I know there is no recommendation or advice for it in AS3600, and my own experience (and from what I've seen others doing) is design & detailing of coupling beams...
Hi guys, thanks for the response. That makes sense. I can seen that figure 8.2.8 is already shown in the 2009 commentary, which explains the situation.
Thanks for clarifying
Hi all,
CL 8.2.8.2, under equation 8.2.8.2(1), it states that the total tension force "need not be more than that required at the section with the maximum tension force demand for flexure, axial, and torsion"
Does this mean to say, that if there is no torsion or axial force, then a cross...
ACI generally refers to single leg ties as crossties, regardless of the end conditions. I like this terminology and think it would be good to adapt.
Additionally, the 70MPa/0.3f'c limit is within the earthquake resistant structures section of the code, not in general requirements for columns...
