Abstract

Rotational seismology deals with the rotational motions produced by seismic events, vibrations, and explosions. It is an emerging field of research that, in past decades, has drawn the attention of the scientific community. However, few studies on the effects of rotational motions on civil engineering structures are currently available. This article adds a contribution to this field of study, focusing on the semiempirical and synthetic modeling of the rotational component of ground motion in the near field of an earthquake and assessing its impact on tall buildings. As an illustration, we consider the 22 February 2011 Mw 6.2 Christchurch earthquake. This event has been characterized by extremely high acceleration values, especially for the vertical component, and extensive liquefaction. First, a classical semiempirical approach is adopted for the modeling of the rotational wavefield, based on the measurements of the translational wavefield from arrays of closely spaced stations. Second, a numerical approach is presented and discussed, based on a 3D model of the Canterbury Plains, which were subject to the February 2011 Christchurch earthquake, and on a kinematic dislocation model. The effect of the rotational wavefield on tall buildings is finally investigated. As an illustration, we evaluate the response, in terms of interstory drift, of the Grand Chancellor Hotel, the tallest building in the central business district (CBD) of Christchurch that experienced extensive damage during the earthquake.

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