STUDY OF IN-SERVICE BRIDGES CONSTRUCTED WITH PRESTRESSED PANEL SUB-DECKS

A RECENT INNOVATION IN PRESTRESSED CONCRETE HIGHWAY BRIDGE CONSTRUCTION UTILIZES PRESTRESSED CONCRETE PANELS AS BOTTOM FORMS FOR THE CONVENTIONAL CAST-IN-PLACE DECK. THE PRECAST, PRESTRESSED PANELS ARE PLACED ON TOP OF THE PRESTRESSED BEAMS, SPANNING THE DISTANCE BETWEEN ADJACENT BEAMS. THIS TYPE OF CONSTRUCTION IS PARTICULARLY ATTRACTIVE WHERE PLACEMENT AND REMOVAL OF CONVENTIONAL FORM WORK IS DIFFICULT AND COSTLY. A FIELD STUDY WAS CONDUCTED OF THREE EXISTING HIGHWAY BRIDGES CONSTRUCTED IN 1963 USING PRESTRESSED CONCRETE PANELS. THE STUDY WAS UNDERTAKEN TO DETERMINE THE CONDITION OF THESE STRUCTURES AFTER SEVEN YEARS OF SERVICE, AND TO SEE IF ANY EVIDENCE OF A LACK OF CONTINUITY OF ACTION BETWEEN BEAMS, PANELS, AND DECK COULD BE DETECTED. THE STUDY INCLUDED MAPPING OF CRACK PATTERNS IN THE CAST-IN-PLACE DECK, SOUNDINGS TO DETECT DELAMINATION BETWEEN PRESTRESSED PANEL AND CAST-IN-PLACE DECK, CORINGS, AND LOAD TESTS. THE RESULTS OF THIS STUDY INDICATE THAT THE BRIDGES INVESTIGATED ARE PERFORMING SATISFACTORILY, AND THEIR STRUCTURAL BEHAVIOR AGREES WITH THAT ASSUMED IN THEIR DESIGN. /FHWA/