IRJET- Analytical Study and Seismic Evaluation of Diagrid Structural System for High Rise Steel

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International Research Journal of Engineering and Technology (IRJET)

e-ISSN: 2395-0056

Volume: 07 Issue: 06 | June 2020

p-ISSN: 2395-0072

www.irjet.net

Analytical Study And Seismic Evaluation Of Diagrid Structural System For High Rise Steel Building Mohammed Hassain B1, Chithra S2 1P.G.

Student, Department Of Civil Engineering, Government College Of Technology, Coimbatore, Tamil Nadu, India 2 Assistant Professor, Department Of Civil Engineering, Government College Of Technology, Coimbatore, Tamil Nadu, India

---------------------------------------------------------------------***--------------------------------------------------------------------The difference between conventional exterior-braced frame structures and current diagrid structures is that, for diagrid structures, almost all the conventional vertical columns are eliminated. This is possible because the diagonal members in diagrid structural systems can carry gravity loads as well as lateral forces due to their triangulated configuration in a distributive and uniform manner. For instance, structural performance of braced tubes and diagrid structures are very similar in a sense that both systems carry lateral loads very efficiently with their structural members axial actions. While bending rigidity in braced tubes is provided primarily by vertical perimeter columns, bending rigidity in diagrids is provided by diagonals which also provide shear rigidity because the system is typically composed of only diagonals.

Abstract - Structural design of high rise buildings is

governed by lateral loads due to wind or earthquake. Lateral load resistance of structure is provided by interior structural system or exterior structural system. Usually shear wall core, braced frame and their combination with frames accounts for interior system, where lateral load is resisted by centrally located elements. Recently diagrid structures which is an exterior structural system is adopted in tall buildings due to its structural efficiency and flexibility in architectural planning. Compared to closely spaced vertical columns in framed tube, diagrid structure consists of inclined columns on the exterior surface of building. Due to inclined columns lateral loads are resisted by axial action of the diagonal compared to bending of vertical columns in framed tube structure. Analysis and design of 36 storey diagrid steel building is presented. A regular floor plan of 36 m × 36 m size is considered. ETABS 2017 is used for modeling and analysis of structural members. All structural members are designed as per IS: 800:2007,IS: 1893-2002 for earhquake loads and IS: 875-1987 for wind loads considering all load combinations. Dynamic along wind and across wind are considered for analysis of the structure. Load distribution in diagrid system ,comparison of analysis results in terms of time period, top storey displacement ,base shear and inter- storey drift is presented in this paper.

The lateral load resisting systems that are widely used are mainly rigid frame, shear wall, wall-frame, braced tube system, outrigger system, diagrid system and tubular system. Diagrid is an exterior structural system in which all perimeter vertical columns are eliminated and consists of only inclined columns on the façade of the building. Diagrid structures are more effective in minimizing shear deformation because they carry lateral shear by axial action of diagonal members[3]. Modifying the structural pattern of a vertical building to optimize its structural efficiency has several benefit. Variation of structural pattern on the perimeter of vertical buildings has given certain aesthetics towards a ubiquitous and monotone prismatic form, especially considering that limitation of site and functional consideration usually does not allow much modification of the vertical building’s form.[2] This paper examines the influence of changing the structural pattern’s granularity towards the efficiency of the structure.Today’s building technology prefer tubular concept for high rise buildings. But diagrid is also an important lateral load resistance system, which can be used for complex geometries of building. Hence, in this study the diagrid building are compared with different geometric patterns in order to reveal the structural advantages of diagrid building. For the comparison six models of diagrid buildings are

Key Words: Diagrid Building; Lateral Load Resistance; Tall Building

1. INTRODUCTION The diagrid structural system can be defined as diagonal members formed as a framework made by the intersection of different materials like metals, concrete or wooden beams which is used in the construction of buildings and roofs. Diagrid structures of the steel members are efficient in providing solution both in terms of strength and stiffness. But nowadays a widespread application of diagrid is used in the large span and high rise buildings, particularly when they are complex geometries and curved shapes.[4]

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