From: "Juan C. Gray" <juangray(--nospam--at)col2.telecom.com.co>
Date: Mon, 17 May 1999 10:38:38 -0700
A crude method would be to find the "center of gravity" in plan of the
respective fllor, using the first order moments (with area) of the
columns in that floor. For a more realistic method , see Paulay and
Priestley's "Seismis design of reinforced concrete frames"
Juan C. Gray