Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Drift at top and rotation/curvature

[Subject Prev][Subject Next][Thread Prev][Thread Next]
-----Original Message-----
From: Juan C. Gray <juangray(--nospam--at)>
To: seaint(--nospam--at) <seaint(--nospam--at)>
Date: Friday, July 30, 1999 11:48 AM
Subject: Re: Drift at top and rotation/curvature

>You should never, never! allow plastic hinges to form on the columns, as
>this will cause the structure to fail mechanically (just think of floors
>moving relative to each other without any constraint) . What you have to
>do is guarantee that the hinges form first in the beams or slabs
>supported by the column and design the moment capacity of columns to be
>greater than that of beams (speaking generally of the joint). You may
>check this in ACI 318-95 , eq. 21-1.

You are confusing design of the primary lateral load resisting system with
compatibilty drift.
It is not necessary or even possible to assure strong column/less strong
beam action in the "gravity" system. It is necessary to assure that collapse
of these elements will not occur.