Filipe Amarante dos Santos

Superelasticity, a unique property of shape memory alloys (SMAs), allows the material to recover after withstanding large deformations. This recovery takes place without any residual strains, while dissipating a considerable amount of energy. This property makes SMAs particularly suitable for applications in vibration control devices. Numerical models, calibrated with experimental laboratory tests from the literature, are used to investigate the dynamic response of three vibration control devices, built up of austenitic superelastic wires. The energy dissipation and re-centering capabilities, important features of these devices, are clearly illustrated by the numerical tests. Their sensitivity to ambient temperature and strain rate is also addressed. Finally, one of these devices is tested as a seismic passive vibration control system in a simplified numerical model of a railway viaduct, subjected to different ground accelerations.

Nowadays, modern analysis of Civil Engineering structures implies the use of increasingly sophisticated computer models, designed not only to predict the response of actual structures to different loadings, but also to simulate the effects of eventual modifications in their structural configuration. Nevertheless, it is often discovered that, when the numerical simulations are compared with experimental data, the degree of correlation is weak preventing the use of the FE models with confidence in further analyses. In such cases, FE updating techniques are available to correct the FE models, based on dynamic response records of the real structures. These updating processes usually consist of four phases: a preliminary FE modeling, an experimental modal identification, a manual sensitivity analysis and, finally, an updating of the FE model. The present paper presents all four phases of a successful updating process for the FE model of a footbridge structure. It is shown how the last phase of the process can be performed fully automatically, by coupling an optimization routine with a commercial FE analysis program.