Effect of Base Width and Stiffness of the Structure on Period of Vibration of RC Framed Buildings in Seismic Analysis

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.

Structural Seismic Damage Assessment Method Based on Structural Dynamic Characteristics

“…So et al (2015) focused on analyzing the mechanical principles and main characteristics of various fundamental period computational formulas, and analyzed the impact of masonry in lled wall, concrete or cement block partition wall on the fundamental period. Sangamnerkar and Dubey (2015) analyzed 36 reinforced concrete frame structures with different underlying dimensions and shaft-spacing structures. And in uencing factors on the fundamental period are researched such as the underlying width, the column cross-section size and the stiffness of the structural basis.…”

Overall structural seismic damage rapid assessment method based on period and displacement response characteristics

“…Sangamnerkar and Dubey 3 analyzed 36 reinforced concrete frame structures with different underlying dimensions and shaft-spacing structures. And influencing factors on the fundamental period are researched such as the underlying width, the column cross-section size and the stiffness of the structural basis.…”

“ Study of Sesmic Analysis of Masonry Wall Structure”

“…In the present work, study of different infill materials on the seismic behaviour of multi-storey building with soft stories is carried out. [14] Floating columns are a typical feature in the modern multistorey construction in urban India and are highly undesirable in buildings built in seismically active areas. In this paper static analysis is done for a multi-storey building with and without floating columns.…”