Design aids for unreinforced masonry under bending compression / Bemessungshilfen für biegedruckbeanspruchtes unbewehrtes Mauerwerk - Part 1: Basics / Teil 1: Grundlagen

The semi-probabilistic safety concept of divided safety factors for action and resistance of DIN EN 1990 [1] led in Germany to a comparison of resisting bending moments and normal forces with the corresponding acting section forces and moments in the structural design of masonry building elements.
Regarding the material properties for masonry under bending compression, fully plastic material behaviour is assumed in DIN EN 1996-1-1/NA [2]. The use of a stress block has been introduced as a material law, which results in the reduction factor &phgr; for the determination of the loadbearing capacity of the section. This describes the ratio of the normal force resistance of the reduced (due to the bending effect) part of the design section under compression and the resistance value related to the total area.
Building on this, design aids are presented here, which are comparable with the &ohgr; tables (called &phgr; table here) and the “general structural design program” of massive building, since common mechanical basics permit this.
The user-friendly handling of the design diagram and design tables is demonstrated through examples in the second part of the scientific paper [3] and the relation to the calculation approaches of DIN EN 1996-1-1/NA [2] is made clear. The relation to the reduction factor &phgr;m, which takes into account the effects of second order theory, is also described in [3], like the use of the reset rule for masonry sections with normal forces acting with large load eccentricities.