spColumn - confinement for modelling shear walls
spColumn - confinement for modelling shear walls
(OP)
Hello All,
I am currently using spColumn to analyze some shear walls to develop interation diagrams. I'm analyzing them as irregularly shaped "columns" within the program. My issue is with the confinement properties that I believe spColumn is applying to the wall - is it allowing distributed vertical reinforcement that is not confined in a zone to act in compression?
KZ
I am currently using spColumn to analyze some shear walls to develop interation diagrams. I'm analyzing them as irregularly shaped "columns" within the program. My issue is with the confinement properties that I believe spColumn is applying to the wall - is it allowing distributed vertical reinforcement that is not confined in a zone to act in compression?
KZ






RE: spColumn - confinement for modelling shear walls
2) The confinement setting are only used to define material resistance factors and define ties size.
3) In core walls, distributed reinforcement between two concentred zone might be in compression even without confinement... where is the problem ?
In my understanding, the confinement are required in corner and wall end or to embded horizontal rebars.
It's not required in distributed zone. if it would be the case, everything in core wall would be confined !
Any tought ?
RE: spColumn - confinement for modelling shear walls
Hope this helps.
RE: spColumn - confinement for modelling shear walls
MarkHirschi: That's a very interesting clause, regarding the <1% Ag. I'm based in Canada, so I wasn't aware of the ACI clause. I don't know if there is a similar clause in the Canadian standard. The capacity reduction factor may be exactly what I'm looking for if I don't trust those bars to be laterally braced.
RE: spColumn - confinement for modelling shear walls
RE: spColumn - confinement for modelling shear walls
THIS IS NOT RELATED to confinement of rebar in compression caused by wall or column bending.
My understanding is that the general practice FOR WALL is to confine ends and corner of wall and design wall tickness accordingly. The resistance calculation where compression rebar is included as effective even if not restrained by ties (like in distributed zone) are common practice.
If you disagree, please provide references.
RE: spColumn - confinement for modelling shear walls
Understand that (a) is not related to confinement. This much is spelled out in the commentary to ACI, which informs that this factor is to account for accidental eccentricity. But it is a factor you could reduce to attempt to account for lack of confinement instead of altering the phi factors. As long as you're under 1% steel then no adjustment would need to be made.
Generally speaking, unless our walls are designed as special shear walls or greater than 1% steel, we do not use lateral ties to confine the walls at any location. Including ends/corners. For low levels of stress and required ductility, this is fairly common and allowed by ACI 14.3.6 as referenced above.
KZSteel-
Another idea would be to use an irregular pattern for reinforcement. Only put reinforcement on the tension end of the wall and make sure you're still okay. Obviously won't work if you reverse the direction of the load, but would eliminate the concern of spcolumn using the steel as compression reinforcement.
RE: spColumn - confinement for modelling shear walls