Behaviour of Exoskeleton Structures under Wind Loading

Abstract

Tall buildings structural system has evolved a lot in recent times. Nowadays, a new system is being in the building as two parts namely exterior system and interior core. The exterior system will be located in the perimeter of the structure whereas the inner core located at the center which mainly accounts for the transfer of gravity load and the exterior system takes care of lateral loads rather than gravity load. The exterior shell is nothing but a diagonal grid which are effective as both gravity and lateral support to the tall buildings and this structural system is named as Exoskeleton. This exoskeleton diagrid structures imparts greater stiffness and lateral stability to the slender tall buildings. The objective of this study is to obtain a shape efficient lateral load resisting exoskeletal system using diagrid elements. Hence, the steel exoskeleton structures are analysed separately for both wind and seismic loads using ETABS 2015. 72-story structure with plan area of 2500 m2 adopted with different base plan (octagonal, rectangular and triangular shapes) with aspect ratio less than 5 has analyzed and designed. Gust factor method is adopted for wind loading since the tall structure undergoes vibration for various acceleration of the wind. The Gusts factor various from 1.19 to 2.11 in the design. Several analytical studies were conducted for different base plan with various diagrid angles and then this paper focus on obtaining a shape effective structure with optimal diagrid angles say 55.5, 65.7, 77.8 degree under adverse loading condition. Moreover, this work is done by considering following parameters say interstory drift, shear absorbing performance, the behaviour of inner core and outer shell.