Masonry Magazine April 1992 Page. 26
END WALL
CROSS WALL
HORIZONTAL SPAN SUPPORTS
(SHOWN IN PLAN)
PILASTER OR
BUTTRESS
ROOF
FLOOR
FLOOR
VERTICAL SPAN SUPPORT
(SHOWN IN SECTION)
Lateral Support Requirements
FIG. 2
Masonry Walls
Masonry walls should be laterally supported in either the horizontal or vertical direction at intervals not exceeding those given in Table 3. Lateral support should be provided by cross walls, pilasters, buttresses or structural frame members when the limiting distance is taken horizontally. Floors, roofs or structural frame members should be used when the limiting distance is taken vertically (see Fig. 2). Cantilever type walls also have a minimum lateral support criteria. The h/t ratio for cantilever walls should not exceed 6 for solid masonry walls nor 4 for hollow masonry walls.
Thickness of Masonry (9.6)
Empirical design requirements pertaining to the thickness of bearing walls and foundation walls are found in Section 9.6. Masonry walls must conform to thickness requirements as well as lateral support and allowable stress requirements. Thicknesses given are nominal dimensions. These requirements are more conservative than empirical design criteria in previous masonry standards.
Bearing Walls
Bearing Walls. The minimum thickness of masonry bearing walls more than one story in height must be 8 in. (200 mm). Bearing walls of one story buildings may be reduced to 6 in. (150 mm). The height to thickness limitation in Table 3 requires a wall of 6 in. (150 mm) in thickness to have a maximum height of 10 ft (3.1 m).
Wall Thickness Changes
Specific provisions are incorporated due to a change in wall thickness between floor levels or floor and roof levels. If a change in wall thickness between floors or between floor and roof levels is desired, the greater wall thickness must extend to the lower support level. Wall thicknesses may be changed to meet fire, sound or thermal requirements. Where walls of hollow masonry units or masonry bonded hollow walls are decreased in thickness, a course or courses of solid masonry should be constructed between the thicker wall below and the thinner wall above. Special units or construction are permitted to be used as long as the loads from face shells or wythes of masonry above are transmitted to the wall system below.
Foundation Walls
Foundation walls have empiri-