Effects of changing temperature in the vibration-based model updating of a masonry bridge

FE model updating of structures is commonly based on the modal parameters evaluated in a single vibration test. Nevertheless, the influence of changing temperatures on modal parameters – especially on natural frequency – is well known. The paper presents an investigation on the effects of (temperature-induced) frequency variations on the estimate of the elastic properties of a historical masonry bridge. Firstly, documentary research, geometric survey, minor destructive tests and ambient vibration tests were performed. Subsequently, the numerical model of the masonry bridge is developed based on the collected data, and the updating procedure is performed by using the two sets of modal parameters identified in July 2018 (average temperature 30.4°C) and April 2021 (average temperature 13.2°C). The results show that the (temperature-induced) frequency decrease seems to affect more significantly the estimate of the Young’s modulus of spandrels and backing.