Mixed-Variable Control for Shear Tests on Massive Reinforced-Concrete Walls

Abstract

Within the frame of the European project IRIS, five reinforced concrete walls have been tested in shear at the ELSA. The thickness of the wall was exceptionally large (40cm) for this kind of test. The testing setup was able to apply quasistatically a shear force of up to 12 MN by means of four horizontal actuators and the vertical load and rotations were controlled by another four smaller actuators. The applied mixed-variable control at the horizontal actuators, with feedback based on a combination of force and displacement, allowed to have a smooth response of the system also in the situations of collapse of the specimen or at the central gap zone in which the horizontal pistons where not in contact with the loading system. In addition to this control, a low-speed regulator algorithm running in MATLAB closed an external loop that managed the variation of the target to the controllers in order to perform the required loops at the specified force or displacement level. This sophisticated setup and control, plus the conventional instrumentation combined to high-resolution photogrammetry, have allowed to perform the tests with a high accuracy in the quantity and uniformity of the load and high quality in the measurements.JRC.G.5-European laboratory for structural assessmen