Strength of masonry subjected to in-plane loading: A contribution

Abstract

a b s t r a c tThe present paper discusses the strength of unreinforced masonry subjected to in-plane loading. Applying the methods of the theory of plasticity, the state of stresses under investigation and compatible failure mechanisms are discussed and an extension (new regime) to an existing failure criterion for in-plane loaded masonry without tensile strength is given. This new regime takes into account slip failure along the head joints line which could be observed in compression tests and which could compromise the safety of the design based on the existing criterion. In addition, a novel proposal for the simplified variation of uniaxial masonry strength as a function of the angle of inclination of the principal compressive stress relative to the head joints direction is derived and proposed for practical applications. Further, the present paper gives an overview of an experimental program comprising the author's own compression tests on wall elements made of concrete and calcium-silicate blocks as well as of clay brick masonry that was carried out at ETH Zurich. The results of these tests, together with those from further tests carried out by other researchers, have been used for the verification of the abovementioned proposal for the simplified variation of uniaxial masonry strength. A satisfactory agreement between the proposed simplification and test data has been found.

Reliability of masonry walls subjected to in‐plane loading: A slip failure along head joints / Zuverlässigkeit von Mauerwerkswänden bei Belastung in der Ebene: Versagen entlang der Stoßfugenflucht

“…However, an additional failure regime, namely sliding failure along head joints, within the failure criterion without tensile strength, is introduced by [19]. [19], Druckstrebe in einer Schubwand [19] Assuming that applied in-plane loads, which in general can act eccentrically, could be transferred through the masonry wall of length l by means of distinct inclined uniaxial compressed stress filed (strut), of length ls, see Fig.…”

“…Thus, it is defined by the set of inequalities (1) to (5) [18], Bruchbedingung [18] Assuming a head joint line as a slip line, no dissipation of energy along head joints, and that the masonry units material satisfies Coulomb's failure criterion [20], equation (7) for a principal compressive stress, 2 ( 2 < 0 = 1 ) is derived by equating the work W, equation (8) and dissipation D, equation (9), see [19].…”

“…4, [19]. Uniaxial strength in strut [19], Einachsige Druckfestigkeit [19] Function for 2 , equation (11), describes the uniaxial strength in strut for ≤ ( 4 + φ/2) ⁄ and for larger or equal to the strut angle of inclination corresponding to the intersection of functions equation (7) and equation (11) Here c is the mortar (bed joint) cohesion whereas  is its angle of internal friction. Slip failure regime along head joints i.e.…”

“…Figure 5. Extended failure criterion [19], Erweiterte Bruchbedingung [19] Masonry wall will not fail, if all inequalities (1) to (6) are fulfilled. On the contrary, the failure of the wall will occur as soon as the resultant stress vector is out of the failure surface.…”

“…Using the following equations (15), (16), (17) and (18) the limit state function, equation (14) can be transformed into more appropriate function, equation (19) for probabilistic analysis.…”