Experimental verification of basic analytical assumptions used in the analysis of structural wall buildings

The observed response of medium high-rise buildings during the latest earthquakes in the USA, Chile, Mexico and Japan have indicated that buildings with structural walls or dual systems of frames and walls behave considerably better during strong shaking. A series of strong motion and ambient vibration records have been obtained in a 22-stories high structural wall Chilean building. Dynamic properties and response characteristics are identified using parametric and nonparametric system identification techniques. A strong coupling of translational modes and very low damping values are observed during medium intensity seismic events and ambient excitations. Typical values for critical damping ratios are between 1 and 2%. Rocking is observed as an appreciable effect on the overall displacements of the structure. Torsional effects are not important in the observed seismic response but they become relatively important during low level ambient excitations. The basic response characteristics identified are compared with those of a three-dimensional model. The model was determined using typical consulting office assumptions. The agreement between model and experimental records is good for global dynamic parameters, and with further adjustment, seismic response can be modeled with a good degree of accuracy validating a series of modeling assumptions.