The effect of rotational component of earthquake excitation on the response of steel structures

This work is on the influence of the rotational component of earthquake excitations to the response of steel structures. In most studies, seismic input is being modeled only using the translational component of the ground acceleration, while the rotational one is ignored. This was due to the observation that the rotational component had minimal effect on low-rise buildings. Hence, the accelerometers used would not measure it, leading to a lack of records. Nowadays, technology provides such instruments and relative records are made available. Indicative of that is that elastic design response spectra for rotational components are introduced to the design codes. In this paper, the results on structural response and internal forces due to the rotational component of a seismic excitation on the steel structures are examined. Dynamic time history analysis and response spectrum analysis of different steel structures are performed (a) considering the rotational component of the excitation and (b) without it. From the numerical results it is shown that the impact of rotational component in structural response and internal forces of the steel structures is significant and should not be ignored during structural design.