FEM updating of tall buildings using ambient vibration data

ABSTRACT: Ambient vibration testing is the most economical non-destructive testing method to acquire vi-bration data from large civil engineering structures. The purpose of this paper is to demonstrate how ambient vibration Modal Identification techniques can be effectively used with Model Updating tools to develop reli-able finite element models of large civil engineering structures. A fifteen story and a forty-eight story rein-forced concrete buildings are used as case studies for this purpose. The dynamic characteristics of interest for this study were the first few lateral and torsional natural frequencies and the corresponding mode shapes. The degree of torsional coupling between the modes was also investigated. The modal identification results ob-tained from ambient vibration measurements of each building were used to update a finite element model of the structure. The starting model of each structure was developed from the information provided in the design documentation of the building. Different parameters of the model were then modified using an automated procedure to improve the correlation between measured and calculated modal parameters. Careful attention was placed to the selection of the parameters to be modified by the updating software in order to ensure that the necessary changes to the model were realistic and physically realisable and meaningful. The paper high-lights the model updating process and provides an assessment of the usefulness of using an automatic model updating procedure combined with results from an ambient vibration modal identification.