Abstract:
Pakistan is located on an earthquake prone area and old bridges were designed without any seismic provision. In the years (2005), tremors were felt in Pakistan due to the strong earthquakes at Kashmir, which highlight the earthquake threat to Pakistan. This study focuses on seismic vulnerability of arch type masonry bridge structures in Pakistan, designed primarily for gravity loads, when they are subjected to earthquakes. A case study has been carried out for the vulnerability study for an 11 m span masonry arch bridge representing typical bridge structure in Pakistan. In the case study, nonlinear dynamic Analysis for the full scale structures are carried out. Three states limits PGA of Collapse (CO), Severe Damage (DS), Limited Damage (DL) along with their relationship with the acceleration, defining its three levels is the main objects to be achieved. The evaluation of the seismic vulnerability is carried out by verification of arch at mid span, piles, shoulders, and near support of the bridge. The capacity vs demand curves are obtained for elements of bridge based on the accelerograms due to the worst earthquake scenario in Pakistan. From these studies, it is concluded that the arch type masonry bridges in Pakistan may suffer some damage due to the worst possible earthquake.
