Reinforced masonry beams under shear load – Proposals for future designs / Bewehrte schubbeanspruchte Mauerwerksbalken – Vorschläge für zukünftige Bemessungen

Abstract

This article is written against the backdrop of the work of the European standardisation committees on the amendment of EN 1996‐1‐1 [N 4] which will also exert an influence on the design of reinforced masonry in Germany. This paper focusses on the design approaches of DIN EN 1996‐1‐1 for untensioned reinforced masonry beams under shear load in the ultimate limit state (ULS). Proposals are made to discuss their revision. The contents of E DIN 1053‐3 [N 3] and of the final draft of the guideline ”Flat Lintels” [7] are taken into account.

Shear resistance of reinforced masonry beams with and without additional concrete or prestress

“…(5). Since either masonry with reinforcement or with prestressing tendons was used for all test samples, the longitudinal strain ε x can be determined with Eq.…”

“…Since either masonry with reinforcement or with prestressing tendons was used for all test samples, the longitudinal strain ε x can be determined with Eq. (5). In contrast to the calculations for reinforced concrete building elements, the internal level arm for masonry z was assumed to be z = 0.85 × d. A comparison of the calculated shear forces resistances V rechn.…”

“…1). In [5] it is demonstrated, that the design approach for the determination of the shear force capacity V R of reinforced masonry according to DIN EN 1996-1-1 [6] is based on obsolete assumptions from reinforced concrete theory for the action of inclined principal compression or tension stresses. The code assumes that theoretical cracks occur with infinitely small crack spacings, which open exclusively at right angles to the crack direction.…”

“…Mauerwerksbalken werden in Deutschland häufig in Form von Flachstürzen [3] oder scheitrecht gemauerten Fertigteilstürzen [4] verwendet (Bild 1). In [5] wurde gezeigt, dass der Bemessungsansatz zur Bestimmung der Querkrafttragfähigkeit V R von bewehrtem Mauerwerk nach DIN EN 1996-1-1 [6] auf nicht mehr aktuellen Annahmen der Stahlbetontheorie für die Wirkung schiefer Hauptdruck-und Hauptzugspannungen basiert. Dort wird angenommen, dass sich theoretisch Risse mit unendlich kleinen Rissabständen einstellen, die sich ausschließlich senkrecht zur Rissrichtung öffnen.…”