Study on Seismic Control of Continuous Girder Viaducts Subjected to Near-Fault Earthquakes

Compared with far-field ground motions, near-fault ground motions are characterized by rich long-period components and significant velocity pulses, posing a serious threat to continuous girder viaducts due to their relatively long natural periods. To study the seismic performance of such structures, a typical bridge was selected as the research object. Key engineering demand parameters, including pier top displacement, movable support displacement, and pier bottom strain, were obtained through numerical simulations subjected to both near-fault and far-field ground motions. The analysis indicated that the original bridge design fails to meet the seismic requirements for near-fault earthquakes. Consequently, a 1:10 scaled model was designed and tested, with the experimental results further validating this conclusion. While viscous dampers have been implemented in bridges in high-intensity seismic regions, their design primarily relies on dynamic elastoplastic analysis and numerical simulations. Furthermore, their design not only lacks systematic experimental verification but also rarely features case histories validated by real earthquakes. To address this gap, viscous dampers were installed on the scale model bridge, and their vibration reduction effectiveness was directly analyzed and validated via shaking table tests. The results confirmed that structural responses induced by near-fault ground motions were significantly higher than those from far-field ground motions. The viscous dampers exhibited excellent performance, achieving a maximum reduction rate of over 50% in key responses, thereby substantially enhancing the bridge’s seismic capacity.