www.sefindia.org

[paresh.patel at babtie...]

Dear All,



I have my comments on point 2 raised by Mr.. Ingle.

Written by Mr..Ingle: CL 4.17 Principal axes can the code through some light
in obtaining the principal axes of an unsymmetrical building. It may be
obtained as axes defining maximum and minimum moment of inertia. I.e. for L
shape building, it may be u-u and v-v axes. I think it may be proper to
study the direction of the fundamental mode shapes (each in principal
direction) of the building. This information can be used in defining the
principal axes of the building for further calculations.

Comment: It is desirable that specific guidelines be available for
determination of principle axis of an unsymmetrical building. But I think
there is no rational approach available by which we can find principle
direction of complex structures. For a complex three-dimensional structure,
direction of an earthquake that produces maximum stresses in a particular
member or at specific point is not apparent. For time history it is possible
to perform large number of dynamic analyses at various angles of input to
check all points for critical earthquake directions. Such an elaborate study
could consume lots of time and financial resources.

Please let us have your views on this.

Paresh Patel
Jacobs Babtie India
Ahmedabad

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