[BS] A112.2 In-Plane Shear of Unreinforced Masonry Walls

Wall piers shall be analyzed according to the following procedure, which is diagrammed in Figure A112.2.2.

1. For any pier,

   1. 1.1. The pier shear capacity shall be calculated as:

      

      (Equation A1-18)

      where:

      A_n = area of net mortared or grouted section of a wall or wall pier.

   2. 1.2. The pier rocking shear capacity shall be calculated as:

      

      (Equation A1-19)

2. The wall piers at any level are acceptable if they comply with one of the following modes of behavior:

   1. 2.1. Rocking controlled mode. Where the pier rocking shear capacity is less than the pier shear capacity, in other words, V_r < v_a, for each pier in a level, forces in the wall at that level, V_wx, shall be distributed to each pier in proportion to P_DD/H.

      For the wall at that level:

      

      (Equation A1-20)

   2. 2.2. Shear controlled mode. Where the pier shear capacity is less than the pier rocking capacity, in other words, v_a < V_r in one or more pier(s) in a level, forces in the wall at the level, V_wx, shall be distributed to each pier in proportion to D/H.

      For each pier at that level:

      

      (Equation A1-21)

      and

      

      (Equation A1-22)

      If V_p < v_a for each pier and V_p > V_r for one or more piers, such piers shall be omitted from the analysis, and the procedure shall be repeated for the remaining piers, unless the wall is strengthened and reanalyzed.

3. Masonry pier tension stress. Unreinforced masonry wall piers need not be analyzed for tension stress.

Shear walls without openings shall be analyzed the same as for walls with openings, except that V_r shall be calculated as follows:

(Equation A1-23)