A Proposed Protocol for Classsifying Corrosion Damaged Prestressed Concrete Pilings on Coastal Bridges

Corrosion induced cracking, delamination, and spalling of prestressed coastal bridge pilings presents a formidable challenge to maintenance and maintenance planning, both in Florida and elsewhere. Particularly needed is a protocol whereby engineers can prioritize corrosion damaged pilings according to deterioration severity and reduced load bearing capacity. In this project, ten pilings on six coastal bridges were inspected; and the dimensions of concrete cracks, delaminations, and spalls were measured. These then served as input to a Priority Ranking equation that was formulated to yield a quantitative number (PR) that is intended to reflect loss of piling load bearing capacity. The same inspection and analysis was also performed for ten pilings from the old St. George Island Bridge. Subsequent to an on-site inspection, the latter pilings were recovered and tested to failure as part of another project. The PR value for the 20 pilings was compared with load capacity analysis results determined using FB-MultiPier and the Florida Department of Transportation Biaxial Column Program software and, in the case of the St. George Island Bridge, experimental strength determinations. A plot of PR versus the percent capacity loss, CL, (analytical and experimental) yielded a best fit curve described by the equation, for which R² was 0.91, thus indicating excellent agreement between the two parameters (PR and CL). Further, a repair prioritization flow chart was developed based upon 1) piling size and length, 2) location of the piling in question within its bent, and 3) condition of adjacent pilings, with decisions based upon PR criteria that were established for the piling in question. Based upon the above, a protocol is proposed as a maintenance planning methodology for corrosion damaged prestressed pilings.