Author(s)

C. Gentile & N. Gallino

Abstract

The paper summarises the application of a dynamic-based methodology for the structural evaluation of an historical suspension bridge. The methodology is based on a field survey of the actual deformed configuration due to dead load, ambient vibration measurement of the response under pedestrians and windinduced excitation, modal identification and finite element model updating. The investigated bridge, dating back to 1928, is about 92.0 m long and is characterised by a timber floor system supported by two couples of cables that were recently replaced, in order to bring the structure up to satisfactory standards of safety for pedestrian loads and light vehicular traffic. Keywords: ambient vibration testing, Frequency Domain Decomposition, finite element model updating, output-only modal identification, suspension bridge. 1 Introduction Many of the suspension bridges originally built with timber floor system after the second half of the 19th century still stand today. These bridges should be considered as historic documents, integrating part of the territory landscape but also as an important resource. A good example is the Morca suspension bridge (Figs. 1-3), completed in 1928, over the Sesia river in northern Italy. The bridge belongs to the traditional and cultural heritage of the region where 9 suspension bridges have been constructed between 1843 and 1928 [1], with 3 of these bridges still standing today. The suspended deck, about 92.0 m long, is in solid timber boards and is supported by two couples of cables that were recently replaced, in order to bring

Keywords

ambient vibration testing, Frequency Domain Decomposition, finite element model updating, output-only modal identification, suspension bridge.