ACI 318 has quite a stringent upper limit on maximum allowable shear stress on diagonally reinforced coupling beams [10SQRTf'c (psi) / 0.83SQRTf'c (MPa)], however the new Zealand concrete code, NZS 3101 states "No Upper limit is placed on the shear force that may be resisted by diagonally...
HD-111, Section 11 tells you to do this.
It doesn't make any sense to choose "limited ductile" or "moderately ductile" if you're building is not behaving in a ductile manner, ie, not going into tension and going beyond the elastic limit.
Agent666, pretty much the majority of buildings in...
If your wall isn't going into tension under the ductile assumption, then you have reduced your EQ load too much and assumed more ductility than the system actually has. Hence the code minimum of tension reinforcement to account for the over reduction.
You should check the tension requirements...
My approach is to build a thorough 3D model and use the T1 period from the modal analysis in place of the T1 period from the code calculation, but only to the point that the base shear is reduced to 70% of that with the code T1, as per section 6.
But if you did a response spectrum, the code is...
Haha Agent666
That's because in the Australian code, a singly reinforced wall without ties has better capacity than a doubly reinforced confined column! And it doesn't define the difference either, so you're free to choose the one that gives you the best (cheapest) result for the contractor...
Retrograde,
It's not a contradiction, its a conservative look at two sides of the same coin.
11.2.1 says that if a wall is completely in compression, you can use one layer of reinforcement (if within the limits of CL11.5).But you have to check this using 100% of the earthquake load (not...
I don't like the idea of grout plastic grout tubes.
I find it interesting that there's so much discussion and focus in the industry about development length, lap length, anchorage, etc, but grout tubes are just thrown around out there without much thought.
I suppose for compression only...
Can anyone recommend any articles, studies, product tech spec sheets for grout tubes?
I see a lot of offices simply specifying a 75mm dia metallic ribbed grout tube, but not a specific product.
Are lap splices (tension/compression) really effective through grouttubes? What length of a "ribbed...
I agree with that: there should not be different rules for walls and columns. They are both compression elements with bending. The magnitude of the load, and slenderness are the variables.
Unfortunately though, the code clearly gives very different rules for each, and if the code will not...
Rapt,
Tmac clearly discusses 2000x200 elements being ignored in a core/shear wall system, the discussion isn't about every possible framing system.
But even still, if the structure only has a series of 2000x200 "columns", they would attract the lateral forces and would have to be designed...
Tmac,
If the 2000x200 blades are small enough that they only attract <3% of the lateral load (total or each?), is it even fair to say they are "walls"?
They sound like "columns" to me, that should be designed to section 10. If the gravity loads aren't particularly large, and they aren't high...
Tmac,
Part of the issue is that (supposedly) section 11 was never intended to be used for isolated blade elements.
Unfortunately, 3600 doesn't clearly define the difference between a section 11 wall and a section 10 column. And as the D&C market has pushed leaner and leaner designs, thin&long...
Raygon,
I think you might be misunderstanding the function and meaning of the ductility factors.
The whole revision of 3600-2018 was to address this misunderstanding which is largely present in Australian engineering design.
That is, the ductility factor is a function of the behaviour of the...
Hi again, just to keep this thread going...
CL14.4.4.3 Axial load limit for elements with u>1. The description says N*/Ag, where N* is the sum of the seismic weights defined in AS1170.4 (earthquake code). So, is this axial load limit only for G + 0.3Q?
It says increased axial load resulting...
Thanks RAPT,
Cl 14.4.4.3 does state "All structural walls", and by definition (and what this thread is all about) shouldn't the 0.2f'c apply to all elements, regardless of their relative stiffness?
On another note, if the dominant element (say lift core) is in tension with a Mu of 2, it can be...
"If the column were a minor stiffness braced by more dominate walls and in double curvature, it probably does not apply to it."
Does this mean then that there is a point where an elements stiffness can be deemed negligible and the tight EQ requirements wouldn't apply? This is essentially what...
Thanks for all the responses
I guess there's still no real conclusion though, as any element connected to a diaphragm, no matter how small, will attract horizontal loads, even if it's just a fraction.
Strange that the new code doesn't have similar restrictions for the column section though...
Hi Rapt,
I was afraid you'd have an answer along those lines, though thank you for the contributions you can give. It's a shame that's how it is. Any chance I can get that third response privately?
The two you've answered are my impressions as well. With the new amendment coming to AS3600, can...
Hi all,
Just want to get some opinions on the changes to "structural walls" in new 2018 AS3600.
Section 14.2.10 defines a structural Wall as:
"Wall (either load bearing or non-loadbearing) connected to floor diaphragms that attracts horizontal earthquake and wind design actions".
At what...
