Monitoring historical masonry structures with operational modal analysis : two case studies

Abstract

The paper addresses two complex case studies of modal and structural identification of monuments in Portugal: the Clock Tower of Mogadouro and the Church of Jero´nimos Monastery, in Lisbon. These are being monitored by University of Minho with vibration, temperature and relative air humidity sensors. Operational modal analysis is being used to estimate the modal parameters, followed by statistical analysis to evaluate the environmental effects on the dynamic response. The aim is to explore damage assessment in masonry structures at an early stage by vibration signatures, as a part of a health monitoring process that helps in the preservation of historical constructions. The paper presents the necessary preliminary dynamic analysis steps before the monitoring task, which includes installation of the monitoring system, system identification and subsequent FE model updating analysis, automatic modal identification and investigation of the influence of the environment on the identified modal parameters.The authors would like to thank Edwin Reynders for his kind support in the automatic system identification. The activities on Monastery of jeronimos were partly funded by the EU-India Economic Cross Cultural Programme "Improving the Seismic Resistance of Cultural Heritage Buildings", Contract ALA-95-23-2003-077-122