International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 11 Issue: 11 | Nov 2024
p-ISSN: 2395-0072
www.irjet.net
Comparative Analysis of RC Structure with and Without Outrigger Using Steel Bracing Nainappareddy Alekhya1, Veda Samhitha2 1M. Tech Scholar [Structural Engineering], Department of Civil Engineering, Siddhartha Institute of Technology
and Science (SITS), Hyderabad-500088, Telangana, India
2Assistant Professor, Department of Civil Engineering, Siddhartha Institute of Technology and Science (SITS),
Hyderabad-500088, Telangana, India -------------------------------------------------------------------------***------------------------------------------------------------------------Abstract
The rapid expansion of tall building construction worldwide has presented new engineering challenges, particularly in ensuring the structural integrity of high-rise buildings under lateral loads. As building height increases, structural stiffness decreases, creating a need for efficient systems to mitigate risks from seismic and wind forces. This study explores the use of outrigger systems, specifically those incorporating steel bracing, to control excessive drift in reinforced concrete (RC) structures. A comparative analysis is performed on regular and irregular buildings with and without outrigger systems, utilizing centrally rigid shear walls and steel bracing as the primary structural components. Models are developed using ETABS software and analyzed using equivalent static and response spectrum methods. The study evaluates key structural performance indicators, such as lateral displacement, drift, storey shear, base shear, and the natural period, to assess the outrigger system's impact on stiffness and efficiency under static and dynamic loads. The results provide insights into minimizing structural and non-structural damage in high-rise buildings subjected to wind or seismic forces. Key Words: Outrigger, Steel Bracing, RC Structures, Lateral Loads, Structural Performance, Seismic Analysis.
1. INTRODUCTION The development of tall structures has advanced significantly due to urbanization and the demand for space-efficient solutions. High-rise buildings are now widely used for residential, office, and commercial purposes. However, the design of tall buildings in seismic-prone regions presents unique challenges, particularly due to lateral forces from wind and earthquakes. A substantial part of India is exposed to high seismic risk, requiring careful design considerations to address these lateral loads (1). Historically, building designs focused primarily on gravity loads, but modern structural systems must account for lateral forces due to the increased slenderness of buildings (2). The structural systems used in high-rise buildings include rigid frames, braced frames, shear walls, and outrigger systems, each of which offers varying degrees of resistance to lateral loads (3, 4). Among these, the outrigger system has emerged as one of the most effective methods for controlling excessive drift and minimizing damage caused by lateral forces (5). The outrigger and belt truss system connects the central core of a building to its external columns through stiff outriggers, effectively reducing lateral deflections (6). This system is particularly beneficial in high-rise buildings exposed to seismic or wind forces, as it helps limit the risk of structural and non-structural damage (7, 8). The outrigger system can be categorized into two main types: conventional outriggers& virtual outriggers. The conventional outrigger system connects the core directly to external columns, while the virtual system uses floor diaphragms to transfer forces indirectly (9). This study compares the seismic performance of reinforced concrete (RC) buildings with and without outrigger systems using steel bracing. A 30-storey building is analysed under lateral loads using ETABS software, employing both equivalent static and response spectrum methods. The study evaluates key parameters such as lateral displacement, base shear, and drift to assess the structural performance (10). The addition of outriggers significantly enhances lateral stiffness, making it a viable solution for tall buildings in seismic zones (11).
2. OBJECTIVES OF THE WORK a) To model and analyse high-rise structures to identify the most effective systems for resisting lateral loads. b) To evaluate the performance of outrigger systems in regular and vertically irregular structures subjected to seismic forces.
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