Field testing of two prestressed concrete girders
"This paper presents the procedures used and the results obtained in a cooperative research project designed to obtain field data to determine the actual behavior during construction and in service of one of the first prestressed concrete structures designed by the Missouri State Highway Department. During the initial planning stage of a pedestrian bridge across the Mark Twain Expressway in metropolitan St. Louis, it was decided to use prestressed, post-tensioned concrete girders. In discussing the design and specifications for the girders, it was suggested that worthwhile technical information could be obtained with a relatively low-cost field observation program. The program was initiated with the design and manufacture of an instrumentation system which would meet the rugged demands of field service condition and yet provide reasonable accuracy. University of Missouri research personnel supervised the installation of all instrumentation appurtenances in the various elements of the structure, and collected all field data. Measurements were made before, during, and after the post-tensioning operations, before and after all major construction operations, and at appropriate time intervals following completion of the structure. To provide the additional information needed for interpretation of the field measurements, a companion test program was undertaken to measure the actual physical properties of representative samples of the materials used in the construction of this structure."--Page 42.