Abstract
A field investigation reported progressively severe scour around a bridge river-crossing PC bridge in southern Taiwan after a series of typhoons and storms. Layout misalignment was found on caissons up to 1.7 m from their designate positions. A retrofit project was executed with concrete to integrate substructures and caissons as one structural element. Unfortunately, embedded caissons were exposed their upper portion on 6 piers in different severities. Failure retrofitting developed as structural discontinuities on 3 piers. Such a deficiency could impinge on the toppling issue of superstructure in case of occurrence of critical flooding or earthquake. A substructural stability analysis indicated its structural stability lying on the unsafe side on the most severe structural detrimental pier for the pier bottom was partially attached atop a caisson without any protection or repair. Finally, temporary substructural retrofitting was suggested to improve the weak linking between pier and caisson.
