Evaluation of Shear Lag Index in High-Rise RC Buildings Having Exo-skeleton Structural System

Abstract

Although framed tube system has been found to be the most efficient system for high-rise buildings, they could experience the shear lag effects which will result in nonlinear distribution of axial stress along the flange and the web of the cross-section of the tall building plan. Exoskeleton structure is generally found to be a self-supporting structural system set outside and suitably connected to a primary inner structure, the latter being enhanced or protected. In this article, by studying three types of concrete structures having 20, 30, and 40 stories with elevations of 80, 120, and 160 m, respectively, the effects of change in the location of openings on Exo-Skeleton structures on the shear lag phenomenon are investigated. The shear lag of the compression wing of the structural models, which are perpendicular to the lateral force application, was studied. Among the index related to the shear lag, two indexes of the shear lag index including the axial stress ratio of each element in the axis to the axial stress of the middle element and the axial stress ratio of the corner element to the tensile stress of the middle element derived from the structural analysis under load side effects were studied. It could be concluded that the most effective opening configuration with the greatest reduction in shear lag is proposed for structures with different aspect ratios.