Structural Survey and Health Monitoring of the "Antenna di Dalmine"

The paper presents an application of structural survey and health monitoring of the main flag post in Dalmine (Bergamo, Italy). The 64m tall steel post, hereon referred as "antenna", as it is called by the citizens, was built in 1936 and represents the highest flag post in Europe. The antenna, symbol of the city of Dalmine, was retrofitted in 1990 due to significant corrosion at the base; after few years the flag, 10x6m, was removed from the antenna for structural safety issues. In 2006 the local government decided to investigate the state of conservation of the antenna before restoring it and replacing the flag. The antenna was subjected to survey of the pipes thickness along the height, video inspection of the interior side and continuous monitoring of the top by means of accelerometers. The data recorded from the accelerometers allowed evaluating the system natural frequencies, the modal shapes, by rovering, and the maximum displacements of the top of the antenna during heavy storms.