From: Dan Connell <dan__connell(--nospam--at)hotmail.com>
Date: Fri, 11 Jun 1999 19:31:51 PDT
I believe in ETABS you can include a torsional loading in load case "c" and
you can include it in your load combination with your dynamic loads d1 and
or d2 instead of adding additional mass. The addition of additional mass
may give you false results for dynamic analysis.
From: "fabricio rosales" <frosales(--nospam--at)webtelmex.net.mx>
Date: Thu, 10 Jun 1999 17:51:25 -0500
We are involved in the design of a two-tower office complex, in Mexico
City. It is composed of a 35-storey and 25-storey buildings. The Mexican
Building Code establishes that the seismic design eccentricity be
1.5es + 0.1b, or
es - 0.1b
where es is the computed eccentricity, and
b the direction perpendicular to the one the seismic force
is being considered
For dynamical (modal) analysis the eccentricity should be reduced to 0.1b
provided that both horizontal displacements coupling and horizontal
displacements and rotations coupling are taken into account.
We are modeling the buildings with ETABS program. The fact is that if we
assign predefined values to the level mass coordinates (in order to
introduce such code required eccentricity) having the selfweight command
assigned, it changes them once the run is performed.
Does anybody knows how to predefine a fixed value for the mass coordinates
having activated the selfweight command?
Opinions and suggestions are all welcomed.
Fabricio Rosales, P.E.
P.S. We don´t consult CSI because the support period has expired long time
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