Einfluss der Belastungsrichtung auf die einaxiale Druckfestigkeit von Proben aus Vollziegeln

Influence of loading direction on the uniaxial compressive strength of solid brick.

The influence of the loading direction on the uniaxial compressive strength is well known from geology in case of cleavage stones. This relation is caused by both the orientation of the single cleavages, the laminar interlock and the gaps within the stone to the loading direction. These phenomenons can cause problems in evaluating the performance of existing structures due to the fact of unexpected low values for the compressive strength. Within this contribution it is discussed, based on small-scale laboratory tests if this correlation is also valid for brick stones. For this purpose two charges from historical bricks from the 19th century and from one series of new bricks disked-shaped specimens were taken. These drill cores were conditioned to equal testing conditions and loaded up to failure according to EN 772-1. These tests show, that in case of machine-made bricks there is an influence of the loading direction to the value of the compressive strength. In case of historical bricks the influence of the loading direction does not exceed the uncertainties and inhomogeneity which are given by the raw material and the manufacturing procedure. The results of this contribution can be used for the assessment of existing structures made of masonry. In these cases material parameters often are unknown and have to be determined by experimental testing.