AS3600 Clause 10.8 - Transmission of Axial Force through Floor Systems
AS3600 Clause 10.8 - Transmission of Axial Force through Floor Systems
(OP)
Hi all, had a couple of questions regarding this clause. I'm early in my career and don't yet always grasp the intent behind the wording in the code (though having read past discussions on this forum, maybe not that uncommon?)
First off, when assessing the joint using the effective concrete strength are we looking solely at the vertical force transmitted through the slab i.e. without consideration of any sort of moment (mainly the minimum) that we would be considering for the column itself? The clause itself only ever refers to the axial transmission but I have a hard time justifying to myself we should be ignoring a moment that the columns themselves must consider.
Secondly, Note 1 at the end of this clause states that confining reinforcement may be used to increase the effective strength of the concrete, and the commentary suggests doing the same. What sort of methods/resources would you use to calculate the increase in effective strength for a certain amount of confinement provided? Calculating a confinement pressure is simple enough given the equations given in Clause 10.7.3, but I am unfamiliar with how one would determine what increase in effective strength arises from this confinement.
First off, when assessing the joint using the effective concrete strength are we looking solely at the vertical force transmitted through the slab i.e. without consideration of any sort of moment (mainly the minimum) that we would be considering for the column itself? The clause itself only ever refers to the axial transmission but I have a hard time justifying to myself we should be ignoring a moment that the columns themselves must consider.
Secondly, Note 1 at the end of this clause states that confining reinforcement may be used to increase the effective strength of the concrete, and the commentary suggests doing the same. What sort of methods/resources would you use to calculate the increase in effective strength for a certain amount of confinement provided? Calculating a confinement pressure is simple enough given the equations given in Clause 10.7.3, but I am unfamiliar with how one would determine what increase in effective strength arises from this confinement.
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RE: AS3600 Clause 10.8 - Transmission of Axial Force through Floor Systems
Second point is a good question. People have asked me that question a few times about how to increase the effective compressive strength of the concrete using confining reinforcement and I don't know. There is nowhere in the code where the compressive strength goes above f'c except for section 10.8 and that clause about bearing surfaces which I don't really like. As far as I know there is not really a precedent for it.
RE: AS3600 Clause 10.8 - Transmission of Axial Force through Floor Systems
RE: AS3600 Clause 10.8 - Transmission of Axial Force through Floor Systems
Trenno - are you referring to Clause 3.1.9 in EN1992-1-1? It seems that clause gives about 5% increase in concrete strength for every 1% (of f'c) in confinement pressure, which to me and the projects I work on seems pretty low compared to the equations in AS3600 10.8, unless we are meant to be considering the effect of the confinement on top of the calculated f'ce values from 10.8.
RE: AS3600 Clause 10.8 - Transmission of Axial Force through Floor Systems