1.1 This International Standard relates to typical responses of people to the horizontal motion of structures in the frequency range 0,063 to 1 Hz. The recommendations are categorized in accordance with the use of the structures and, in the case of off-shore fixed structures, with the nature of work being carried out. Injury of occupants due to structural vibration is outside the scope of this International Standard. 1.2 Whole-body motion caused by structural vibrations induced by infrequent external environmental forces is considered separately from whole-body motion resulting from structural vibrations caused by frequently occurring force actions. Frequently occurring force actions may arise from external sources, machinery or structure services such as elevators, fans, air conditioners, heating units and plumbing. Both perceptible magnitudes of low-frequency horizontal motion of structures and magnitudes likely to raise minimum adverse comment are included. NOTES 1 Visual perception of building motion, the influence of torsional oscillations of structures and the effects of noise may influence the subjective response to vibrations of structures but no quantitative assessment is made. 2 Blasting, earthquakes and similar events are excluded from the scope of this International Standard. 3 An off-shore fixed structure is one founded on the sea bed, such as a gravity platform or a steel jacket with a piled foundation. Floating structures, tension leg and articulated platforms are excluded from the scope of this International Standard. 4 In buildings, the response of people is for a normal adult population and, although it is known that levels of vibration considered acceptable vary with age groups and sex, no definite correction factors can be put forward at present to adjust the acceleration magnitudes for these influences. On off-shore fixed structures, the recommendations only apply to trained personnel. 5 This International Standard applies to horizontal motion of structures as perceived by human beings in any posture, sitting, standing or reclining.