TITLE:
Effect of Base Width and Stiffness of the Structure on Period of Vibration of RC Framed Buildings in Seismic Analysis
AUTHORS:
Prakash Sangamnerkar, Sheo Kumar Dubey
KEYWORDS:
Base Dimensions, Dynamic Analysis, Natural Period of Vibration, Stiffness
JOURNAL NAME:
Open Journal of Earthquake Research,
Vol.4 No.2,
May
12,
2015
ABSTRACT: Fundamental natural period of vibration T of the building is an important parameter for evaluation
of seismic base shear. Empirical equations given in the Indian seismic code for the calculation
of the fundamental period of a framed structure, primarily as a function of height, do not consider
the effect of stiffness of the structure, base dimensions of the structure, number of panels in both
the directions, amount of infill and properties of the infill. The fundamental period can be evaluated
using simplified expressions found in codes, which are based on earthquake recordings in
existing buildings, laboratory tests, numerical or analytical computations. These technical codes
provide expressions which depend on basic parameters such as building height or number of stories.
Building periods predicted by these expressions are widely used in practice although it has
been observed that there is scope for further improvement in these equations since the height
alone is inadequate to explain period variability. It is also known that the period of a RC frame
structure differs depending on whether the longitudinal or transverse direction of the structure is
considered. The aim of this study is to find the effects of building base width in both the directions,
stiffness of the structure etc. and to predict the fundamental period of vibration of reinforced concrete
buildings with moment resisting frames (MRF). A few examples of dynamic analysis are presented
in this study to show the effect of base dimensions and stiffness of the structure in calculating
the time period of the structure. And it is recommended to be incorporated in the formula
for evaluating the natural period of vibration of structures.