Experimental modal analysis of civil structures: State of the art

Modal testing and system identification, here defined as experimental modal analysis or EMA, is a vital component in evaluation of in-service structures. Many of the techniques used in this structural engineering discipline were developed for aerospace application, but structural engineers have taken both hardware and software and adapted them for the demanding applications of in-situ and in-operation structures. Forced vibration testing (FVT) remains the 'gold standard' for system identification due to the capability to control the excitation and to estimate modal mass directly, but ambient vibration testing (AVT) is the only option for large structures. AVT has become increasingly popular, largely thanks to the power of operational modal analysis algorithms developed during the last two decades and is often used alongside FVT to provide complementary system identification. The presentation will use examples such as Liffey Bridge (Dublin), Rugeley Chimney and Humber Bridge to identify milestones in the development of EMA technologies.