TIME-DEPENDENT BEHAVIOR OF SEGMENTAL CANTILEVER CONCRETE BRIDGES

Three segments of the Kishwaukee River Bridge were instrumented to measure concrete strains, temperatures, and vertical bridge deflectiosn for a period of five years. Simultaneously, tests to measure short-term and long-term physical properties of concrete used in the bridge segments were performed. Using the measured concrete properties and the detailed construction records, time-dependent deformations of the instrumented bridge segments were calculated by a computer program using a step-by-step numerical procedure. Comparisons were made between measured and calculated values. Comparisons of the measured and calculated results verified numerical procedure for calculating long-term behavior of segmental box-girder bridges. Using the numerical procedure, effects of time-dependent behavior of conncrete on axial deformations, prestress losses, moment redistribution, and concrete stresses on continuous box girders were investigated. Influence of concrete ages at times of erection on bridge behavior was discussed. (FHWA)