Core-drilling technique for in-situ stress evaluation in concrete structures

SummaryFor assessing the existing stresses in distressed reinforced concrete/prestressed concrete structures, the concrete core-drilling technique can be used. This core-drilling technique is a stress measurement technique in which a small core is drilled on the structure and the strain perturbations around the core are measured by instrumenting strain gages aligned in the same direction. Laboratory studies were conducted to evaluate the reliability of this concrete core-drilling technique. Calibration coefficients were evaluated experimentally for the used gage length, location, and configuration. Comparison was also made with coefficients evaluated theoretically. This technique is suitable for prestressed concrete girders where girders are prestressed in one direction (longitudinally). Also in reinforced concrete members like columns, compression zones of beams on the major bending axis (along the span) can be evaluated for their in-situ stresses. This concrete core-drilling technique can be used to determine the in-situ stress with enhanced sensitivity in “in-service” prestressed concrete structures.