Seismic Fragility Of Reinforced Concrete Bridge Piers

Bridges, the chief component of the lifeline, are the most important structures in a highway system, play an important role in earthquake relief work. Historical seismic events have shown that, bridges are vulnerable to earthquakes. When earthquakes occur, bridges may subject to severe risks of damage, it will cut off the roadway in the seismic region which can delay the relief work and result in serious economic losses after earthquakes. For these emergency activities, it is essential to evaluate the bridges'safety and operability immediately after earthquakes. The assessment and prediction of damage to highway systems can provide valuable information for post-earthquake response and recovery purposes. Also it can determine whether the bridges can maintain under the aftershocks. Besides, it can evaluate the bridges' remain seismic capacity and draw up the retrofit schemes.Bridge fragility curves, which express the probability of a bridge reaching a certain damage state for a given ground motion parameter, play an important role in the overall seismic risk assessment of a transportation network. This paper presents an analytical methodology for developing fragility curves of the reinforced concrete bridge piers, and evaluates the bridges' function under different PGA. Based on this work, this paper indicate the seismic damage by stiffness degradation and use the capacity spectrum method to calculate the pier's seismic damage under different level of ground motion. Then analyze the influence of seismic damage to seismic demand and pier's capacity. At last, plot the fragility curves of the pier which consider the seismic damage. It shows that the pier which considered the seismic damage is more vulnerable than considered.