A three component force transducer for reinforced concrete structural testing

The design, manufacture and calibration of two special force transducers, capable of measuring the axial force, shear, and bending moment at the base of a structural column are presented. The special force transducers were fabricated to measure the reactions at the base of the exterior columns of a reinforced concrete three-bay, two-story test specimen. The force transducers had the following capacities: 35 kN for axial load, 4 kN for shear, and 3 kN m for bending moment. These values include a safety factor of 2.0. Each force transducer was composed of six independent load cells. Four of these load cells were placed vertically and the other two diagonally. In total, eight calibration tests were conducted on each of the two transducers to form a calibration matrix for converting the six load cell readings into three reaction components. The results of the calibration procedure were very successful with the differences between the applied and calculated values generally less than 2%. The two force transducers were subsequently used in a frame test and they provided an excellent way to measure the internal forces without significantly affecting the overall behavior of the structure.