Design models of reinforced masonry walls under monotonic and cyclic loading

Reinforced Masonry offers several advantages for low cost housing in seismic regions. Widely accepted design criteria, however, are not available — although several design rules are provided in several Codes. This paper is a contribution to the research needed towards a possible improvement of design recommendations, based on the following rational data: (a) Recognition of all failure modes, and (b) Specific contribution of force transfer mechanisms, such as tensile strength and compression strength of masonry, masonry to masonry friction, pullout force of steel bars and dowel action. Thus, using first principles and specific data from recent experimental results, several closed formulae are derived in this paper, predicting shear loads of (i) cracking (ii) tensile disintegration of the web and (iii) diagonal compression crushing of R.M. cantilever and double fixed walls. Ultimate loads proposed by this paper, as well as critical shear loads proposed by several Codes, are also calibrated through a data bank of 55 large scale experiments; conclusions are drawn regarding their validity.