FIELD MEASUREMENT OF DAMPING AND NATURAL FREQUENCY OF AN ACTUAL STEEL-FRAMED BUILDING OVER A WIDE-RANGE OF AMPLITUDES

In order to understand the dynamic characteristics of a prefabricated steel building, several vibration tests with a wide range of amplitude s were carried out. Under excitation with relatively small amplitude l evels, four different construction stages are prepared, The dynamic pr operties such as natural frequencies and damping ratios are evaluated using several identification methods based on observation records, The variability in the results due to the differences in identification m ethods and excitation conditions is examined. By comparing the results at different construction stages, the effect of non-structural member s on the structural stiffness and damping ratio is studied. Using a me chanical exciter, forced vibration tests were carried out for several high excitation levels (100-3000 kgf). Free vibration tests using a wi re cutting method were also carried out for several initial displaceme nt levels (5-25 tonf, as initial tensile force levels). Based on the r esults of these vibration tests with various amplitude levels, the eff ect of non-structural members on dynamic characteristics is studied fr om the view point of amplitude dependence.