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# Re: Ductility demand and Ductility capacity

• To: seaoc(--nospam--at)seaoc.org
• Subject: Re: Ductility demand and Ductility capacity
• From: Tom Chiu <Tomchiu(--nospam--at)worldnet.att.net>
• Date: Thu, 26 Feb 1998 10:22:32 -0800

```youngkj(--nospam--at)mail.dwconst.co.kr wrote:
>
>
> I've performed pushover analysis for two buildings.
> The specified story drift is 1/50.
> The ductility is calculated as the ratio of the last story drift to the
> elastic drift.
> For examples, ductilitys for both buildings are 2.5 and 3.5 respectively.
> Is it possible to say that the ductility demand of the building with 2.5 is
> higher than that of the other ?
______________________________________________________________________

The ductility demand ratio of 3.5 is higher than 2.5, it simply mean
that for that particular drift (demand force), the structure needs to
undergo an inelastic deformation of 3.5 x elastic deformation.

> If that is correct, how can I obtain the ductility capacity of those
> buildings ?
______________________________________________________________________

you can trace and plot the hinge formation at each stage of yielding to
see if you have reached a collapse mechanism stage.  Just keep on
pushing the structure further until it is at the verge of collapse.

Tom Chiu, SE
Thomas Engineering

```