This paper summarizes the results of a comprehensive study of floor acceleration demands on nonstructural components. The study is based on analytical studies on buildings responding elastically and nonlinearly to earthquake ground motions. Buildings analyzed range from 3 to 18 stories. Parameters evaluated include: fundamental period of vibration, lateral resisting system, damping ratio, level of ground motion intensity relative to the intensity that triggers nonlinear behavior. The study included the following aspects: (1) parametric study of peak floor acceleration demands in buildings responding elastically; (2) parametric study of floor response spectral ordinates in buildings responding elastically; (3) development of response spectrum analysis for estimating peak floor acceleration demands; (4) dynamic interaction between primary and secondary systems; and (5) peak floor acceleration demands in buildings responding nonlinearly. Results indicate that the amplitude of acceleration demands in buildings and their variation along the height are strongly dependent on the period of vibration, lateral resisting system and damping ratio of the building and therefore, current US recommendations that compute acceleration demands that are independent of the period, damping and lateral resisting are inadequate. It is also shown that alternative code procedures based on linear response spectrum modal analysis are equally inadequate. The most important trends are summarized.
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