A sensor instrumentation method for dynamic monitoring of railway bridges

One of the most effective ways for investigating dynamic behaviour of mechanical and civil structures under service conditions is dynamic load testing. The outcomes of dynamic tests are vibration characteristics, and in particular modal parameters such as vibration mode shapes, frequencies, damping ratios. Dynamic diagnosis technique has been already used for many years in mechanical engineering. During the last decades a number of investigations have been performed introducing new dynamic monitoring techniques of civil infrastructures including bridges. Field experimental testing of new steel-concrete composite railway bridge was carried out to determine natural and forced vibration frequencies, corresponding mode shapes and damping ratios. The attention was focused on short-term dynamic monitoring of new innovative structure with the aim to investigate the implementation of sensor technique on real structures, to calibrate a FE model of the bridge that can be used for further simulations and as a result to give feedback to the design of similar structures. Field tests and numerical simulations were conducted using excitations induced by dropping a weight and by ambient traffic excitation loadings. Results of these investigations are presented in this paper.