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STAAD Commands and Input Instructions
Section 5
5-212
5.31.2.8 NTC (Normas Técnicas Complementarias)
Seismic Load
Purpose
The purpose of this command is to define and generate static
equivalent seismic loads as per Code of the México Federal
District (Reglamento de Construcciones del Distrito Federal de
México) and Complementary Technical Standards for Seismic
Design (y Normas Técnicas Complementarias (NTC) para Diseño
por Sismo -Nov. 1987) (Chapters 8.1 8.2 8.6 and 8.8)
specifications. Depending on this definition, equivalent lateral
loads will be generated in horizontal direction(s).
Description
The seismic load generator can be used to generate lateral loads in
the X & Z directions for Y up or X & Y for Z up. Y up or Z up is
the vertical axis and the direction of gravity loads (See the SET Z
UP command). All vertical coordinates of the floors above the
base must be positive and the vertical axis must be perpendicular
to the floors.
Methodology :
The design base shear is computed in accordance with Sections 8.1
or 8.2 of the NTC as decided by the user.
A. Base Shear is given as
Vo / Wo = c / Q
c: obtained by the program from the following table
SeismicCoeficient c GROUP A GROUP B
Z-I 0.24 0.16
Z-II not shadowed 0.48 0.32
ZIII y Z_II shadowed 0.60 0.40
Q: is entered by the user as a parameter.