Abstract Although bridge structures might seem at a first sight as rather linear and simple structural systems, their actual performance under earthquake loading is more complicated than that of ordinary buildings, because bridges have typically an order of magnitude larger overall and cross-sectional dimensions, different energy absorption mechanisms, more significant contribution of higher modes, while they are most commonly crossing non-uniform soil profiles. Notwithstanding the significant research progress made to date which has already shed some light on many bridge engineering problems, the development of a realistic earthquake motion scenario is still associated with the highest relative uncertainty compared to maybe all other design and construction aspects. This is even more pronounced in the case of long bridges, where the variation of ground motion among its supports in terms of arrival time, frequency content and amplitude, can strongly affect both the pseudo-static and the dynamic component of the system. It is the objective of this presentation to discuss the applications of structural health monitoring for the investigation of the impact of asynchronous (i.e., spatially variable) seismic excitation on the seismic response of long bridges, based on numerical evidence and the monitored response of specific bridges recently constructed along the new 780km Egnatia highway in northern Greece (a highway consisting of a total 40km of bridges, most of them located in areas of high seismicity and an unfavorable mountainous topography). Emphasis is also given on the monitored response of the 400m cable-stayed Evripos bridge that connects the Evia island to the Greek mainland, during the 1999 Athens earthquake. Despite the long distance from the earthquake source, the simultaneous free-field and on-structure recordings reveal interesting patterns of higher mode excitation and subsequent dynamic behavior that cannot be a-priori predicted using the conventional analytical methods and the existing design code provisions. Based on the above comparative studies, an effort is made to identify means to extrapolate the insight gained through health monitoring in order to improve our understanding on the dynamic response of the entire, interacting soil- bridge system under asynchronous excitation and to propose ways for assessing its potentially detrimental influence in advance. About the Speaker Dr. Anastasios Sextos is Assistant Professor of Information Technologies in Earthquake Engineering at Aristotle University of Thessaloniki, Greece (www.asextos.net). His main research interests are in the fields of information technologies for analysis and design of RC structures and bridges, computational earthquake engineering, software development, numerical analysis of complex structures, soil-structure interaction and rehabilitation of historical structures. He got a Diploma in Civil Engineering from Aristotle University (1997), an MSc on Earthquake Engineering and Structural Dynamics at Imperial College London (1998), and his Ph.D. in Bridge Engineering from Aristotle University (2001). He has authored 14 journal papers, 2 books, numerous book chapters and papers in conference proceedings. Moreover, he is currently a Fulbright visiting scholar at the University of Illinois, whereas he has been visiting scholar at the University California at Berkeley in 2007. He has received scholarships and fellowships from the Deutscher Akademischer Austausch Dienst, Germany, the Engineering and Physical Science Research Council, U.K., the Bodossaki Foudation and the Institution of Public Scholarships, Greece. He is the PI of a European Union Research Project (www.exchange-ssi.net) on hybrid simulation and soil-structure interaction involving participants from Greece, France, Italy and the U.S. (UIUC). Since 2009, he is the General Secretary of the Hellenic Association of Earthquake Engineering (affiliated to the European Association of Earthquake Engineering).