INVESTIGATION OF CORROSION IN THE STEEL H-PILES SUPPORTING THE RICHMOND-SAN RAFAEL BRIDGE

THE SUBSTRUCTURE OF THE RICHMOND-SAN RAFAEL BRIDGE WAS CONSTRUCTED IN 1953 TO 1956. THE PIERS ARE SUPPORTED ON PILES DRIVEN TO BED ROCK OR DEEP GRAVEL BEDS TO TIP ELEVATIONS AS MUCH AS 250 FT. BELOW MEAN SEA LEVEL. DETAILS ARE GIVEN OF CONSTRUCTION. BACKFILL WAS DEFERRED UNTIL THE ACTION OF THE TIDAL CURRENTS ON THE NEW CONSTRUCTION COULD BE STUDIED. AN EARLY CORROSION STUDY WAS MADE. IN 1969 AND 1970, SOME OF THE STEEL BARS CUT FROM STEEL PILE SEGMENTS SUSPENDED UNDER THE RICHMOND-SAN RAFAEL BRIDGE PIERS WERE RECOVERED, WASHED, CALIPERED AND WEIGHTED DISCLOSING LOSS OF SECTION AS HIGH AS 15%. TWO PIERS WERE INSPECTED; ONE WAS PIER 57 ON WHICH BACKFILL HAD PERIODICALLY REQUIRED REPLENISHMENT OVER THE 15-YEAR PERIOD. THE OTHER WAS PIER 27 ON WHICH NO FURTHER BACKFILL HAD BEEN PLACED FOLLOWING THE ORIGINAL CONTRACT IN 1956. AT PER 27, VERY LITTLE, IF ANY, LOSS OF METAL WAS FOUND ON THE PILES. AT PIER 57, LOSS OF SECTION OF 7.5% WAS RECORDED AS ALMOST UNIFORM FROM THE CONCRETE TO THE BOTTOM OF THE LENGTH EXPOSED. THIS PIER HAD STOOD UNBACKFILLED FOR ABOUT A YEAR AFTER COMPLETION. FROM THE FINDINGS, WHICH BRIEFLY SHOWED NO LOSS AT PIER 27 AND CONSIDERABLE LOSS AT PIER 57, FROM THE DIFFERENCE IN UNDERLYING MATERIAL, AND FROM THE DIFFERENCE IN EXPOSURE BEFORE BACKFILLING, A POSITIVE EFFORT TO DETERMINE THE PRESENT RATE OF METAL LOSS, IF ANY, AT PIER 57 APPEARED NECESSARY. THREE TYPES OF DEVICES WERE INSTALLED: A PERMANENT ULTRASONIC PROBE, A STRAIN GAUGE INSTRUMENTED BOLT, AND A VIBRATING WIRE STRAIN GAUGE. THE PRINCIPAL FINDINGS FROM THE INSTALLATION COULD BE OF GREAT IMPORTANCE IN FURTHER STUDIES OF FOUNDATION PILE CORROSION PROBLEMS. THE APPLIATION OF CATHODIC PROTECTION TO THE STEEL FOUNDATION PILES OF THE RICHMOND--SAN RAFAEL BRIDGE IS EXTREMELY COMPLEX AND POSSIBLY NOT FINANCIALLY FEASIBLE. HOWEVER, INFORMATION OBTAINED FROM THIS TEST PROGRAM AND FROM RELATED TEST PROGRAMS AND STUDIES WILL SERVE TO DEVELOP CONSTRUCTION PROCEDURES THAT WILL MINIMIZE CORROSION LOSSES AT MODERATE OR LOW COST. THE PROVEN ECONOMIES OF THIS METHOD OF PIER CONSTRUCTION ARE SUCH THAT MORE PROTECTIVE OR POSITIVE BACKFILL PROCEDURES OR MATERIALS MAY BE EMPLOYED WITHOUT PRICING THIS CONSTRUCTION METHOD OUT OF USE. /DOT/

  • Authors:
    • Balala, B
  • Publication Date: 1972-9

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  • Accession Number: 00209763
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 2 1973 12:00AM