International Journal of Civil and Structural Engineering Research ISSN 2348-7607 (Online) Vol. 9, Issue 1, pp: (21-29), Month: April 2021 - September 2021, Available at: www.researchpublish.com
PERFORMANCE BASED DESIGN OF TALL BUILDINGS WITH RESPECT TO HORIZONTAL EFFECTS Anupama Kamani1, Antonio Capsoni2 1 2
M.Sc. Graduate, Politecnico di Milano, Milan, Italy
Professor, Department of Architecture, Construction Engineering and Built Environment, Politecnico di Milano, Milan, Italy
Abstract: When high rise buildings exposed to high winds are located in low-to-moderate seismic areas, such as Mumbai, wind forces can dominate over seismic demand. Current code specifications cope with these two sets of actions individually, largely relying on the dominant action. A new design approach, based on structural performance, is hence suggested and desirable when facing the risk involved with both hazards. In recent years, there has been a revived and growing interest in reconsidering and updating the standard specifications of the codes, introducing new analytical methods that are performance based. Adapting emerging methods, such as performance based design (PBD), will reliably forecast the behavior of the structure with an higher degree of reliability, risk assessment, safety and optimization. The present work aims, first, to conduct a preliminary analysis to describe the dominant action between the wind and the earthquake, and then to find the required, relevant, ductility demand. Further, by using a FEM code (Midas Gen), the ductility from the actual structure is evaluated and compared to the preliminary study and, finally, the saving in terms of weight of reinforcement between the ductility detailing required for code standards and PBD is assessed. Keywords: High wind, Low to moderate seismic force, Dominant action, Performance based design, Conceptual PBD, Ductility.
I. INTRODUCTION High rise buildings have received a renewed interest in many growing metropolis around the world, where land is scarce, as per their economics, sustainability and other benefits [1]. Tall structures are often associated with lateral loads, basically wind and earthquakes. In areas that are prone to experience both these hazards, structures are finally designed for the more demanding among the two loading conditions. In this approach the belief is that the standard assures probability of exceedance for the considered limit states that are essentially identical to the risks inherent in standard provisions for regions where only wind or earthquakes occur. But this belief is, in general unwarranted. The structures in regions with significant wind and seismic hazards can have risk of exceeding of limit states that can be up to twice as high as corresponding risks implicit in the provisions for regions where only one of these hazards dominates [12]. Generally, several favourable features of wind design are unfavourable for earthquake design and vice versa. Heavy and solid structures characterized by higher stiffness properties resist wind action better, while attract greater seismic loading. On the contrary, light and more flexible constructions, able to adequately dissipate energy by developing plastic hinges and diffused cracks, show a better response to earthquake actions, while are more sensitive to wind forces and vibrations [17]. If the lack of consideration of multi hazard design in regions with high probabilities of both events could result in high casualties and economic losses [18].
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