Danish Building Research Institute, DK-2970 Hørsholm, Denmark


The shear and torsional strength of bed joints are essential parameters to analyse masonry walls subjected to in plane and out of plane forces. This paper presents results from triplet tests with 15 different brick-mortar combinations and torsion tests [1] with the same 15 combinations. For each combination 6 replicates were made for each test method and the average coefficient of variation was 14.5% for the triplet test and 7.3% for the torsion test. Using simple calculation models, the shear strength and the angle of friction was determined from the results of the torsion tests. The values of shear strength agree reasonable well with the results of the triplet test. The relatively small value for the coefficient of variation for the torsion test indicated that this test could, with advantage, replace the triplet test for the determination of the shear strength and angle of friction for bed joints.