Experimental study of the behaviour of building structural elements under soft impact

Abstract
Dynamic three-point bend tests are performed on small beams specimen made of a quasi-brittle material. The most classical hypotheses needed to analyse the tests with SHPB, which are based on a state of quasi-static balance of the body, cannot be used. In order to get the behaviour it is necessary to perform a transient analysis of the specimen response. In most cases, the useful duration of the test – the elapsed time between the beginning of the load and the total failure – is lower than the time needed by the waves to reach the supports. The test is thus called a “one point bending test”. In the case of bending failure, an analysis of the tests is possible by using only the measures given by the input bar. The technique is based on the knowledge of the analytical solution of the transient elastic response of the specimen. The failure mechanisms involved are specific features of the dynamic response. Different failure modes can be observed according to the loading rate: bending or shear fracture, single or multiple fractures. The determination of the bending moments and the rotations of the beam section, where the failure occurs, lead to an estimation of the strength and the failure energy.