Seismic vulnerability assessment of a typical RC highway bridge in high seismic zone

Seismic loads can cause severe damages to bridge, and lead to malfunction of transportation networks. Dissimilar to the static behaviour, the dynamic response of bridges depends on several structural parameters such as material properties, damping and mode shapes. Furthermore, earthquakes characteristics can significantly change the structural response. Depending on the seismicity of local site, the vulnerability assessment of bridges are commonly expressed through fragility functions, which represent the probability of exceeding prescribed levels of damage for a wide range of ground motion intensities. The objective of this paper is to develop analytical fragility curves for a typical reinforced concrete (RC) highway bridge to assess bridge seismic vulnerability. A fragility curve represents a graphical relationship of the probability of exceeding a particular damage level under a seismic excitation of a given intensity. As a case study, Shadchay RC bridge located in Tehran-Saveh Highway is modeled using the OpenSees platform. Nonlinear static pushover and time history analyses are conducted for the bridge using 3D finite element method. Past earthquake ground motion records were used with different hazard levels. The bridge components considered include the columns, decks, bearings and abutments. Fragility curves were developed for structural components as well as for the whole system. The resulting fragility curves for both the components and the system show that the bridge is vulnerable. Component fragility curves are useful tools to identify weak parts of the structure to guide for strengthening or retrofitting while system fragility curves are useful in seismic risk assessment of the structure.

کلیدواژه ها:

Highway bridge ، fragility curve ، numerical analysis ، seismic vulnerability