PREDICTION OF STRUCTURAL RESPONSES USING NATURAL FREQUENCY MEASUREMENTS

Abstract

This paper demonstrates that prediction of structural responses can experience significant errors due to the modelling errors or uncertain input even for simple structures. The responses of two simple reinforced concrete beam, as as examples of simple structures, were measured to be compared with the prediction . To improve the predictions, the relationship between static stiffness and modal s tiffness of a structure is determined, which provided a basis for using the measured natural frequencies replacing the calculated natu ral frequencies, where modelling errors are normally occur. Using the natural frequency measurements significantly improves the quality of the predictions of the two actual beams. As applications, to predict the static response of a real seven storey concrete building and the dynamic response of a simple supported reinforced beam subjected to jumping loads are developed. The prediction of static response of the building using the first two measured natural frequencies during cons truction is close to the numerical prediction, this is due to the building is a test building does not have secondary elements such as walls, beams and partitions in it . The quality of the prediction of the dynamic response of a concrete beam subjected to jumping loads improves signi ficantly from the use of the measured natural frequency.