8/17/2019 4. Masonry Design - Shear

1/2

  7

4. MASONRY DESIGN - SHEAR 

So far, consideration has been given to masonry subject to flexural bending stresses. However,when members are subjected to bending, they are also required to resist shear forces, and theresulting shear stresses must generally be investigated.

4.1 Characteristic and Design Shear Strength 

The characteristic shear strength of masonry in the horizontal direction of the horizontal planeis given by:

 f v = f vko + 0.6 gA

where f v should be taken as not greater than 1.75 N/mm2 for masonry built in thin layer mortar andmortar strength classes M12 and M6 / designations (i) and (ii) or 1.4 N/mm2 for masonry builtin mortar strength classes M4 and M2 / designations (iii) and (iv).

The characteristic initial shear strength of masonry,  f vko, may be:

a) determined by tests in accordance with BS EN 1052-3;

b) taken as 0.35 N/mm2 with clay/cal silicate units having less than 40% formed voids and concrete units

having less than 50% formed voids for masonry built in thin layer mortar and mortar strength classes M12

and M6 / designations (i) and (ii); or

c) taken as 0.15 N/mm2 for masonry built in mortar strength classes M4 and M2 / designations (iii) and (iv). 

4.2 Resistance to ShearProvision against the ultimate limit state of shear being reduced may be assumed where theshear stress due to the horizontal design load is less than, or equal to, the design shear strength:

where vh  is the shear stress produced by the horizontal design load calculated as actinguniformly over the horizontal cross-sectional area of the wall.

8/17/2019 4. Masonry Design - Shear

2/2

  8

Ex:

Check the shear stress at the base of the wall shown in Figure. Assume mortar designation (ii).