On the loadbearing capacity of masonry walls subjected to concentrated end strip loads

Concentrated loads in masonry walls are caused by point loads resulting from beams or columns perpendicular to the horizontal joint. In theory, locally occurring multi-axial stress conditions lead to compressive stress underneath the area subjected to the load, the numerical values of which are greater than the mono-axial compressive strength of the masonry. Load increase factors derived from this and stated in [1] and [2] were last determined in Germany approx. 30 years ago [3] using standard test specimens (in accordance with [4]) and not using walls. The types of masonry investigated at the time were made up of types and sizes of masonry units and of types of mortar and joint configurations that were common at the time; this however no longer appears current. The loadbearing capacity of the wall was completely ignored. In view of current structural design methods based on EC 6 [5] where applied and internal force variables in building elements are compared, this remains unsatisfactory.

For this reason, experimental and theoretical investigations of partially loaded walls (l/h/t = 1.875/1.75/0.115 m) made of aerated concrete and brick masonry with thin-layer mortar were carried out at the Ostwestfalen-Lippe University of Applied Sciences. In addition to the type of masonry unit, the detail of the perpendicular joint was varied (with mortar (v) versus without mortar (uv)). Below follows a report on the result of these investigations.