Non-Destructive Testing of a Cable-Stayed Bridge in Lisbon

This paper discusses objectives, methodologies and results from a campaign of non-destructive investigations on a cable-stayed bridge in Lisbon (Portugal). Among the investigations held, the campaign encompassed dynamic testing of the stay cables in order to identify their natural vibration frequencies and to estimate their tension force. A frequency-domain output-only approach was carried out to identify the natural frequencies of the cables. Subsequently, the cable tension force was estimated on the basis of the flat taut string model. In an advantageous and cost-effective way, vibration tests were carried out without the interruption of the vehicular traffic. Results of the testing campaign were finally incorporated in the bridge condition assessment and used to provide both short- and long-term maintenance prescriptions.