Numerical modeling and experimental modal analysis of a concrete grand-stand structure to structural health monitoring purposes

In the last years public administration has been paying close attention to structural health monitoring of large civil structures used in public events, both to safety and comfort purposes. Since summer 2003 Politecnico di Milano has started a large measurement campaign on the G. Meazza stadium in Milan concerning the static and dynamic structural behavior and the problem of steel and concrete corrosion to asses structural safety. The Meazza stadium is a very complex structure, it is composed of different concrete substructures, built in different ages, each one with different characteristics and different dynamic behavior. This paper deals with a part of this campaign, particularly with the study of the dynamic behavior of one of the stadium sub-structures. Dynamic tests are based on vibration measurement performed both during public events (grandstands full of people) and in the empty stadium. To the aim of reaching a satisfactory comprehension of these measurement results a traditional modal analysis of the grandstands has been performed and the obtained results were used to set-up a reliable FEM model of the considered grandstands. The FEM model, and the results obtained from a permanent vibration monitoring system that is being developed at the moment, are the bases of a reliable structural health monitoring program of the stadium.