Development of field testing procedures to determine the behavior of steel piles supporting integral abutments

The Tennessee Department of Transportation has constructed over 1000 jointless bridges throughout the state. One of the primary concerns with the construction of jointless bridges is response of the bridges to thermal lateral loading. Of particular interest is the behavior of steel piles supporting integral abutments. Hence, the focus of this research is to assess the behavior of the abutment/pile interface and the interaction of the embedded pile Avith the soil. The research team at The University of Tennessee will assess the behavior of steel piles supporting integral abutments by performing a series of field tests on driven piles. However, before such testing begins field testing procedures for the embedded piles have to be established. The development and verification of field testing procedures were accomplished by performing various laboratory tests and a prototype field test. Field testing procedures for laterally loaded piles were established by conducting several tests. A total of six laboratory tests were performed. These test results were useful in assessing the performance of various devices used to monitor the behavior of the pile. Two of these tests were performed to calibrate weldable strain gages and another two to validate measured data output. The remaining two tests were used to simulate an abutment/pile under lateral loading. The lateral load tests of the steel piles showed that the concrete of the abutment failed in tension. After the laboratory tests were completed, a pilot pile was instrumented with strain gages and pressure sensors and then driven into the ground. Lateral loads were then applied at 27 inches above the ground surface. Measured strains were successfully converted into meaningful data that described the behavior of the pile. The bending moments along the length of the pile were calculated using the measured strain data. These bending moments were used to calculate the shear forces, slopes, and deflections of the pile and the pressure of the soil. These calculated results were compared to the moment, shear, pressure and deflection diagrams generated by the COM624P computer program. The comparisons indicated that the diagrams calculated from the measured strains were in general agreement with the graphs computed by COM624P.