Research on seismic safety, retrofit, and design of a steel cable-stayed bridge

After the 1995 Great Hanshin Earthquake, Japanese design specification of highway bridges was revised and many piers and bearing supports have been retrofitted. Large span bridges such as arch, truss, and cable-stayed bridges located in bay area of Kobe city also suffered damages from this earthquake. Therefore the investigation of seismic performance of long span bridges has been conducted for large earthquake. The Aratsu bridge constructed in 1987 is a steel cable-stayed bridge of 345m length, continuous three spans, and single plane of stay cables. The seismic performance of this bridge was examined by nonlinear time history analyses using tri-linear back bone and hysterecis loops. Furthermore fiber model analysis and FE analysis are successfully used to check the behaviors of this bridge. According to the analysis of the target bridge, weak members for large earthquake have been clarified. Install of damper and displacement restrainer, and strengthening of components of bearing supports are proposed retrofit countermeasures. The behavior of retrofitted bridge satisfies the criteria of design specification of highway bridges.