The results of ambient vibration tests on 32 steel-framed buildings, conducted to determine their vibration periods are presented. One aim was to compare the measured periods with the period formulas suggested by Iranian Seismic Code (Standard 2800). These formulas are obtained from US codes and their suitability for buildings in Iran cannot be taken for granted, because of differences in construction materials and processes. Tested buildings, in most of the cases, are regular buildings and have different structural systems with numbers of stories between 5 and 27, and were designed according to the provisions in the Code 2800. First and second translational and torsional periods were identified from AVS records. In nearly all of the cases, the measured translational periods fall below the code curve. Although the formula in the 1st edition of the code, which is of the form αH/√D, gives period values closer to the measured periods in comparison with formulas of the form αHβ in the 2nd edition, it was concluded that based on statistical analysis, from the point of view of 'form' it doesn't seem to have considerable and clear privilege over the equation of the form αHβ. A comparison with vibration periods of buildings in Japan, obtained from dynamic tests, is also made. The first to second and translational to torsional period ratios were also calculated and discussed.
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