Abstract

This article presents the results of the continuous vibration monitoring and modal parameter identification of a 55 story shear-wall concrete building under construction. The building has a near elliptical floor shape with 61x34 meters maximum plan dimensions and 196 meters in height. Metal hysteretic energy dissipating devices have been incorporated into the building to reduce the vibration due to earthquake excitations. The continuous monitoring network is composed by 3 accelerometers on the 20th story and had the objective of identifying the variations of modal parameters induced by the construction process. Ambient and earthquake records have been obtained during monitoring period. The dynamic characteristics of the building were identified using parametric and non-parametric techniques such as the Spectrogram and the Stochastic Subspace Identification (SSI) methods. The procedures obtain the variations of modal parameters with a resolution of ten minutes. The recorded motions were used to validate 15 different Finite Element Models (FEM), created according to the construction progress of the building. The mathematical model frequencies were correlated with the results of the identification procedures; maximum differences between 2% and 14% were obtained. The difficulties of monitoring vibration and modal identification during construction process are indicated and causes of main differences between design and real structure are commented. ©2010 Society for Experimental Mechanics Inc.