Study of Acceleration Demands and Floor Spectra Based on High Amplitude Instrumented Building Records

ABSTRACT Building nonstructural components (NSCs) are attracting more and more attention for its enormous construction cost and huge potential loss under earthquakes. Floor acceleration or floor spectral acceleration is one of the critical seismic demands of acceleration‐sensitive NSCs. Constant values or equations according to structural types, stories are usually used as a design value for floor acceleration amplification (FAA) factor in current codes in various countries. However, these values have not been validated by high amplitude records, where the acceleration may change its probabilistic distribution. This study establishes a dataset including 33 buildings and 175 floor motions, and the critical parameters such as distribution of floor acceleration along the structural height, mean value and distribution of acceleration amplification factor at the roof, normalized floor spectrum, and other key factors influencing the floor spectrum are analyzed. The results indicate that the FEMA P‐58 equations for floor acceleration are generally applicable but suggest adjustments to higher amplification factors especially in steel frame structures. A constant value of 2.70 with an 84% confidence interval is suggested for code‐oriented design, and probabilistic distribution of floor acceleration should be considered. The peak period of the floor spectrum could occur near either the fundamental period of the structure or the ground motion's predominant period, and the amplification factor of floor spectral acceleration over ground spectral acceleration at structural period could be set to 10.