Abstract
In this work a seismic analysis of structure associated with the complete description of ground motion components is performed. All earthquake excitation components corresponding to the six degrees of freedom, translational and rotational ones need to be taken into account for a realistic simulation of structural performance. The impact of the rotational components of an earthquake to the overall response of a steel structure is examined. Typically, in response to the history analyses, the seismic input is descripted by its translational component only, while the rotational components are ignored. This is because the rotational component requires special devices to be recorded in adequate detail. This is one of the reasons why this component is often ignored. With the currently available technology, such an instrument can be constructed and provide detailed records that can be used for the response history analysis of structures. The applicable design codes using a simplified response spectrum analysis accounting for rotational components is proposed and elastic design response spectra are introduced. Another reason why the rotational component was not taken into account in structural analysis is that it does not have significant effect on low-rise buildings. In this work, the analysis results in terms of response and internal forces when accounting for the rotational component is demonstrated. A case study on the response history analysis of symmetrical and non-symmetrical steel structures subjected to earthquake excitation with and without the rotational component of the excitation was performed. Numerical results show that the influence of the rotational component on the structural behaviour is important and should be taken into account in the design process.
Highlights
A detailed response history analysis of a structure requires a full description of the earthquake excitation, using all its components in a three-dimensional space
The numerical results, is indicated the response of in terms displacement,From acceleration and base shear,itwhen they arethat subjected to rotational structures in terms of displacement, acceleration and base shear, when they are subjected to and translational components is higher than the structural response when subjected to translational rotational and translational components is higher than the structural response when subjected to component only
The ratio of the response considering the rotational component of the excitation over that ignoring ranges from 1.1 to 1.6
Summary
A detailed response history analysis of a structure requires a full description of the earthquake excitation, using all its components in a three-dimensional space. Falamarz-Sheikhabadi et al [15,16] worked on the effects of both time-delay and loss of coherency in order to derive simple mathematical expressions for generating the middle-field rocking acceleration component and its corresponding response spectra They revised the seismic intensity parameters in order to account for the combined action of horizontal and rocking seismic motion on structures. EN1998-6, [19], that focuses on the design of slender and tall structures such as towers, chimneys and masts, takes into account the special variability of the seismic ground motion including rotational components of the ground accelerations It proposes an extended response spectrum analysis which requires response spectra of rotational accelerations to be implemented.
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