AS3600 - WALLS DESIGNED AS COLUMNS

[GRADSTRUCT]

HI ALL,

As per 11.2.1 (a) (ii) and (b) (ii), if the walls are designed as columns, the clause 10.7.1 (a) ( columns to have atleast 0.01Ag reo) applies. I am trying to use lightly reinforced "non ductile" structural walls (mu = 1) in my project (not including the shear walls). These walls are precast walls and I want to use SL92 MESH each face. By providing vertical pw < 0.01 and horizontal pw > 0.0025, I can override the restraint requirements of 10.7.4. But the SL92 MESH each face is less than the 0.01Ag requirements of 10.7.1.

These walls (esp the ones in the ground floor) are quite heavily loaded in compression (N* > 0.5phiNu), but I am not relying on the reinforcement for compressive strength, concrete alone is enough. I read in the AS3600 supplementary that the 0.01Ag requirement for reo can be ignored if Asc*Fy > 0.15N* because the reinforcement should take atleast 15% of the compressive load. Does that mean there is no way around this clause? I have to provide N16-200 each face to meet the requirements of 10.7.1?

Thank you in advance.

 

[Retrograde]

I am trying to use lightly reinforced "non ductile" structural walls (mu = 1) in my project (not including the shear walls).

Are you designing the shear walls for a different mu value? You cannot do that - the whole structure needs to be designed for the same mu.

Does that mean there is no way around this clause?

I don't think there is.

 

[GRADSTRUCT]

Ahh okay, thank you! No I havent designed the shear walls yet, hoping it works with mu = 1 loads

 

[SRL V1.0]

Refer AS3600-2018 amendment 2.
11.2.1.a.ii & b.ii have been updated to refer to 10.7.1.b only (4% max reo limit). When checking a wall segment 'as a Column' the lower limits are the normal 0.15% / 0.25% to 11.7.1 or that required by the Column design check.
Remember to keep clause 11.7.4 in mind, which has been expanded on in amendment 2.

 

[Retrograde]

Good points SLR V1.0

I need to refresh my memory of those clauses.

 

[li0ngalahad]

Are you designing the shear walls for a different mu value? You cannot do that - the whole structure needs to be designed for the same mu.

That's not quite right, I believe, as long as these are not primary lateral resisting elements. The code for example specifically requires to design as non-ductile any walls with aspect ratio H/L<2.
So for example if you have a building with moderately ductile cores and shear walls, you can still have other elements that have a lower level of ductility, as long as you design them with the correct load level. The important thing is the failure hierarchy, getting the primary lateral resisting elements to develop plastic hinges while the secondary structural elements remain elastic (i.e. designed as non ductile, with a much higher load). At least this is my understanding.