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Re: Performance/Ductility

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I would think that curvature ductility goes down with increased axial load. The yield curvature increases while the ultimate curvature decreases as, for one thing, you would expect to get spalling at an earlier stage. Therefore, I would guess that a lower bound estimate of the curvature ductility would be assuming a maximum load. To determine the capacity,
however, you would of course have to check both maximum and minimum axial load cases.


satd(--nospam--at)techie.com wrote:

> Hi,
>
> I am working on performance evaluation of a 10 story SMRF and am using non-linear dynamic analysis for this purpose.  The analysis computes the curvature ductility demands at the ends of members based on an effective moment of inertia (.7Ig for columns and .5Ig for beams -FEMA273) and the P-M envelope for the designed section based on ACI stress block.
>
> For computing the curvature ductility capacities for a group of similar (same design) COLUMNS, what level of axial load should I assume for a meaningful comparison of the calculated demands.
>
> In reality, every column will exhibit maximum demands at different level of axial loads and hence, even if the designs are similar, their ductility capacitites will be different.  Since, I have several columns in this structure, could there be a logical "mean" value of axial load that I may use for computing a somewhat "lower bound" of ductility capacity?
>
> Any thoughts in this regard will be very much acknowledged.
>
> Thanks,
>
> Regards,
>
> Sat.
>
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