International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Issue: 07 | July -2017
p-ISSN: 2395-0072
www.irjet.net
STATIC AND DYNAMIC ANALYSIS OF R.C BUILDING FRAME WITH INFILL Nasratullah Zahir1, Dr. Vivek Garg2 1 M.
Tech. Research Scholar, Department of Civil Engineering, Maulana Azad National Institute Technology, Bhopal, India. 2 Assistant Professor, Department of Civil Engineering, Maulana Azad National Institute Technology, Bhopal, India. ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Masonry infill panels are widely used as partition walls as well as external walls of the building to fill the gap between RC frames. The infill masonry may be of brick or concrete blocks. Considering the effect of infill masonry wall, it would increase the mass of the building. The earthquake shaking produces inertial forces which are proportional to the mass of the building, though, it will increase strength and stiffness of the building and reduced time period. Although, in most cases, the ignorance of this property of masonry infill wall in designing of the RC frame may lead to an unsafe design. In present work G+9 6-bay by 3-bay RC building frame situated in seismic zone V as per IS: 1893(part 1)-2002 is analyzed with and without infill masonry wall using Staad pro software. The masonry infill has been modelled as an equivalent diagonal strut element and infill panel. The width of equivalent diagonal strut element is obtained by various approaches given by Smith, Holmes and Paulay. Static and response spectrum analysis is carried out on bare and infill frame models. The results obtained from the analysis for infill frame are compared in terms of story shear, floor displacement, story drift, time period and vertical support reaction with bare frame. The results obtain from the analysis indicates that story shear and vertical support reaction increase, floor displacement, story drift, time period decreases for infill frame models compare to bare frame model by equivalent static method and response spectrum method. This increase in ratio is found to be more at roof compared to base of structure. Key Words: Seismic evaluation, infill masonry wall, Static and Dynamic analysis, Story shear, Floor displacement, Story drift, Vertical support reaction, time period. 1. INTRODUCTION Significant experimental and analytical research effort has been expended till date in understanding the behaviour of masonry infilled frames. Infills interfere with the lateral deformations of the RC frame; separation of frame and infill takes place along one diagonal and a compression strut forms along the other. Thus, infills add lateral stiffness to the building. The structural load transfer mechanism is changed from frame action to predominant truss action (Fig1), the frame columns now experience increased axial forces but with reduced bending moments and shear forces.
(a) Frame action in in infilled frame (b) Predominant truss bare frame action Fig 1: Change in the lateral load transfer mechanism owing to inclusion of masonry infill walls. When infills are non-uniformly placed in plan or in elevation of the building, a hybrid structural load transfer mechanism with both frame action and truss action, may develop. In such structures, there is a large concentration of ductility demand in a few members of the structure. For instance, the soft-storey effect (when a storey has no or relatively lesser infills than the adjacent storeys), the
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