Monitoring concept for the propagation of compressive fatigue in externally prestressed concrete beams using digital image correlation and fiber optic sensors

Abstract

The fatigue of concrete has been the subject of research for many years, and yet, there are still open questions. In particular, the fatigue-induced damage evolution accompanied by a stress redistribution process propagating through the concrete structure is still not fully understood. So far, there are only few experimental studies addressing the fatigue propagation through a material zone occurring, for example, in beams with a pulsating, nonuniform stress profile. To investigate the influence of such stress configurations on the material and structural degradation process, a measuring concept has been developed combining digital image correlation, fiber optic sensors, and conventional strain gauges. The presented experiments visualize the propagating fatigue degradation in the compression zone of prestressed concrete beams subjected to fatigue loading. Based on the developed measurement concept, the quantitative foundation for a comprehensive validation of design rules and material models accounting for concrete fatigue can be significantly extended.