Abstract： Based on a cable-stayed double-tower bridge with the main span of 680 m， a half-bridge model was designed and built with a scale of 1∶40. By using shaking table test， the feasibility of the half-bridge model to reflect the behavior of the whole-bridge model subjected to longitudinal seismic load is studied. The boundary condition of the cable-stayed bridge with double towers was simplified as the half-bridge model， and the simplified boundary condition was verified by comparing the dynamic characteristics of two modelsThe symmetric boundary condition was designed and the shaking table tests on different halfbridge model structural systems subjected to longitudinal seismic loading were conducted. The efficacy of viscous dampers with longitudinal settings to mitigate the seismic response of cable-stayed bridge was investigated. It is found that given the uniform excitation ground motion at different PGA values， the half-bridge model yields similar seismic responses as the full-bridge models. In addition， the viscous dampers are effective in suppressing the seismic response of the cable-stayed bridge with floating system.
