Deflection limitation of reinforced masonry building elements under bending is undertaken according in DIN EN 1996-1-1:2013-02, Section 5.5.2.6, Table 5.2 [N 4], by limiting the span lef or the ratio of lef to the effective depth d, for example lef/d ≤ 20 for simply supported beams. A further requirement in DIN EN 1996-1-1:2013-02, Section 7.3, states that reinforced masonry elements should not deflect excessively under serviceability loading conditions. For reinforced masonry with dimensions, which are within the limits stated in clause 5.5.2.6 [N 4], acceptable vertical deflection of a beam can normally be assumed.
In this scientific paper, the figures stated in [N 4] for the limitation of the bending slenderness lef/d of reinforced masonry beams like masonry or prefabricated lintels are checked by calculation with the “&zgr; procedure” from reinforced concrete theory. The suitability of this procedure was first demonstrated by comparing calculated and experimentally obtained values.
It was determined that maintenance of the bending slenderness ratio lef/d ≤ 20 for the tested calcium silicate masonry lintels does not always lead to deflection values w/lef ≤ 1/250. For prefabricated straight (flat arch) calcium silicate lintels and horizontal aerated concrete lintels with limit slendernesses of lef/d ≤ 15 and calcium silicate masonry lintels with lef/d ≤ 10, w/lef ≤ 1/250 was fulfilled.
With regard to future requirements for the tested reinforced masonry constructions, a method is proposed for the calculation of the limit slenderness ratio lef/d, which leads to maintenance of w/lef ≤ 1/250. Furthermore, the presented “&zgr; procedure” enables reliable calculation of deflection figures at the serviceability limit state considering long-term effects.