To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
Subject: RE: Metal stairs & story drift
From: Nicholas Blackburn <nblackburn(--nospam--at)fdgoak.com>
Date: Wed, 7 Feb 2001 13:48:46 -0800
Stairs are a life-safety item i.e: they are expected to be functional during
events that may render the elevators inoperable (fire, seismic).
The UBC (section 1921.7) requires that all frame members that are assumed
not to contribute to lateral resistance be detailed to accommodate Delta M.
This usually section applies to concrete columns and beams but I usually
extend it to any concrete stairs that we design for the above stated reason.
However, I would extend the analogy to steel design as it is desirable to
have the stairs function during/after an earthquake.
I hope this helps
Nick Blackburn, PE