Torsional Amplification Factors for Non-Structural Components in Torsionally Irregular Buildings

Abstract

This study examines how acceleration-sensitive non-structural components' seismic response is affected by inherent building torsion. A set of elastic torsionally irregular step-back reinforced concrete moment-resisting frame buildings are examined under bi-directional seismic excitations in order to accomplish this goal. For different damping ratios of nonstructural components, the floor torsional amplification factors are determined as a function of the tuning ratio. These factors are defined as the ratio between the floor spectral ordinate at the flexible/stiff edge and the floor spectral ordinate at the center of rigidity. In accordance with the floor displacement-based torsional irregularity indices suggested by the national building codes of the United States and India, the correlations between the peak torsional amplification factors at various floors for the rigid and flexible non-structural components are examined. The torsional amplification factors are shown to be depending on tuning ratio and building parameters. For both the rigid and flexible non-structural components, it is also found that these torsional amplification factors have a strong correlation with the respective floor displacementbased torsional irregularity indices. The very flexible non-structural components, on the other hand, have torsional amplification factors that trend to unity and are therefore seen to be independent of the building's and the non-structural components' features. To design acceleration-sensitive non-structural elements in torsionally irregular structures, floor displacement-based models that are simplified and numerically validated are suggested as a way to calculate the torsional amplification factors. These models can be combined with the current codes.