Potential scour evaluation around piers of historical masonry arch bridges: a case study

Bridge scour could be blamed as one of the main causes of failures in masonry arch bridges. Consequently, foundation settlements due to scour are the most threatening cause of damage for historical bridges because of their hidden nature, the capacity to affect the integrity of the whole bridge and the sensitivity of the arches to displacements. Pier settlements produce the development of cracking mechanisms in the arch barrels which affect the global stability of the bridge and lead to irreversible failures and full collapse. Scour estimation in these bridges is a difficult task because of the geometric complexities and existing different shapes of footings. Many empirical equations as well as laboratory data are presented for prediction of the maximum scour depth in bridge piers; however, an equation that especially describes the scour depth in piers with footings has not yet been presented. The scope of this study is to evaluate the scour in the historical Sio-Se-Pol Bridge in Isfahan, Iran. Constriction scour and local scour are computed and their sum is considered as the total scour in the bridge. Comparison of the computations and laboratory results shows an acceptable correlation. Consequently, the existing equations are precise to estimate such scour depths.