Harish A. Kadam, et. al. International Journal of Engineering Research and Applications www.ijera.com ISSN: 2248-9622, Vol. 12, Issue 7, (Series-I) July 2022, pp. 153-165 www.ijera.com DOI: 10.9790/9622-120701153165 153 | Page Parametric Study of Factors Influencing Mode Shape of Oscillation Harish A. Kadam * , Rahulkumar R. Sharma ** * M.Tech. (Structural Engineering) Student, M.G.M.’s C.O.E, Nanded, Maharashtra, India, ** Assistant Professor, M.G.M.’s C.O.E, Nanded, Maharashtra, India, ABSTRACT The mode shape of oscillation associated with a natural period of building is the deformed shape of the building when shaken at the natural period. Hence, a building has as many mode shapes as the number of natural periods. The deformed shape of the building associated with oscillation at the fundamental natural period is termed its first mode shape or fundamental mode shape of the building. In this study, an attempt is done to understand the various parameters which affect the fundamental mode shape of RC building. The parametric study is done as per the provision of Equivalent Static Lateral Force Method; IS1893 (Part-1): 2002. In this present work, a reinforced concrete special moment resisting frame building models are prepared and analyzed in ETAB software to evaluate the effect of stiffness of structural elements, the effect of degree of fixity at member ends, the effect of building height, and the effect of unreinforced masonry on fundamental mode shape of buildings. Normalization-scaling technique is used in which data points are shifted and rescaled so that they end up in a range of 0 to 1. Building height and Storey Lateral Displacement are normalized in a range of 0 to 1. To calculate the Normalized mode shape, the maximum lateral displacement of the top story is considered as 1 and the remaining story displacement is calculated in proportion to 1. Similarly, the total building height is considered as 1 from the base and the remaining floor height is calculated in proportion to 1. Keywords – Equivalent static method, Mode Shape, Infill panel, , Flexural Stiffness --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 15-07-2022 Date of Acceptance: 29-07-2022 --------------------------------------------------------------------------------------------------------------------------------------- I. INTRODUCTION A mode shape is a deflection pattern related to a particular natural frequency and represents the relative displacement of all parts of a structure for that particular mode. Buildings oscillate during earthquake shaking. The important dynamic characteristics of buildings are modes of oscillation and damping. Mode Shapes of Buildings depend on Overall Geometry of Building, Geometric & Material Properties of Structural Members, and Connections between the Structural Members and the Ground at the Base of the Building. 1.1 Mode Shape Mode shape of oscillation associated with a natural period of a building is the deformed shape of the building when shaken at the natural period. Each node is free to translate in all the three Cartesian directions and rotate about the three Cartesian axes. Hence, a building has as many mode shapes as the number of natural periods. For a building, there are infinite numbers of natural period. But, in the mathematical modeling of building, usually the building is discretized into a number of elements Regular buildings have these pure mode shapes. Each node is free to translate in all the three Cartesian directions and rotate about the three Cartesian axes Irregular buildings (i.e., buildings that have Irregular geometry, non- uniform distribution of mass and stiffness in plan and along the height) have mode shapes that are a mixture of these pure mode shapes. 1.2 Fundamental Mode Shape of Oscillation There are three basic modes of oscillation, namely, pure translational along X-direction, pure translational along Y-direction and pure rotation about Z-axis (Fig 1.1). Regular buildings have these pure mode shapes. Figure 1.1: Basic modes of oscillation: Two RESEARCH ARTICLE OPEN ACCESS