N Mojsilovi?(1)and J SCHWARTZ(2)
(1) Institute of Structural Engineering, ETH Zurich
(2) Institute of Construction Engineering, HTA Lucern

The Swiss structural masonry code provisions are based on the lower bound theorem of the theory of plasticity. The combination of vertical and inclined parallel stress fields (struts) within a shear wall is assumed to transfer the resultant of axial and shear forces through the wall. The stresses in the struts are supposed to stay within the boundaries of the failure criterion, which, in this case, is represented by the uniaxial compressive strength of masonry. This strength depends on the inclination of the stress field. In order to be usable for practical purposes the theoretically derived dependence is first simplified and then applied to derive the code design charts for shear walls (axial force – shear force interaction). The charts are derived by combining statically admissible vertical and inclined stress fields within the shear wall, thus delivering the safe solution. The best lower bound is found by varying the inclination of the inclined strut.