Masonry Magazine May 1975 Page. 19
TABLE 1. Maximum Vertical Spans (feet) for Hollow Nonreinforced Concrete Masonry Walls (Built with Type M or S Mortar) Subjected to Uniformly Distributed Wind Load, w (psf)*
| Nominal Wall Thickness (inches) | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 |
| :------------------------------ | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 6 | 13.6 | 9.6 | 7.8 | 6.8 | 6.1 | 5.5 | 5.1 | 4.8 | 4.5 | 4.3 |
| 8 | 18.0 | 12.7 | 10.4 | 9.0 | 8.0 | 7.3 | 6.8 | 6.3 | 6.0 | 5.6 |
| 10 | 21.9 | 15.4 | 12.6 | 10.9 | 9.8 | 8.9 | 8.2 | 7.7 | 7.3 | 6.9 |
| 12 | 25.4 | 17.9 | 14.6 | 12.7 | 11.3 | 10.3 | 9.6 | 8.9 | 8.4 | 8.0 |
*Design assumptions: (1) Simply supported spans; (2) Architectural or engineering inspection provided; (3) Allowable flexural tensile stress 23 psi, increased 1/3 for wind; (4) Wall weight neglected; (5) Actual wall thicknesses 3/8 inches less than nominal wall thicknesses; and (6) Section modulii based on net mortar bedded area; S = 46 in. 3 for 6-in. wall: S80 in. 3 for 8-in. wall: S = 118 in. 3 for 10-in. wall; and S159 in. 3 for 12-in, wall.
TABLE 2. Maximum Horizontal Spans (feet) for Hollow Nonreinforced Concrete Masonry Walls (Built with Type M or S Mortar) Subjected to Uniformly Distributed Wind Load, w (psf)*
| Nominal Wall Thickness (inches) | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 |
| :------------------------------ | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 6 | 19.3 | 13.6 | 11.1 | 9.7 | 8.6 | 7.8 | 7.3 | 6.8 | 6.4 | 6.1 |
| 8 | 25.5 | 18.0 | 14.7 | 12.7 | 11.4 | 10.3 | 9.6 | 9.0 | 8.5 | 8.0 |
| 10 | 31.0 | 21.9 | 17.8 | 15.5 | 13.8 | 12.6 | 11.7 | 10.9 | 10.3 | 9.7 |
| 12 | 35.9 | 25.4 | 20.7 | 18.0 | 16.1 | 14.6 | 13.6 | 12.7 | 11.9 | 11.3 |
*Design assumptions: (1) Simply supported spans; (2) Architectural or engineering inspection provided; (3) Allowable flexural tensile stress 46 psi, increased 1/3 for wind; (4) Actual wall thicknesses 3/8 inches less than nominal wall thicknesses; and (5) Section modulii based on net mortar bedded area (face shell area); S46 in. 3 for 6-in. wall; S80 in. for 8-in. wall; S-118 in. for 10-in. wall; and S 159 in.3 for 12-in. wall.
TABLE 3. Minimum Required Area of Steel (sq. in./ft.) For Reinforced Concrete Masonry Walls*
| Requirements - NCMA "Specification for the Design and Construction of Load-Bearing Concrete Masonry" | t, Actual Wall Thickness (inches) |
| :----------------------------------------------------------------------------------------------------- | :--------------------------------- |
| | 3.625 | 5.625 | 7.625 | 9.625 | 11.625 |
| Minimum Area in One Direction = 0.0007 bt | .0304 | .0472 | .0640 | .0808 | .0976 |
| Balance of Minimum Area in Other Direction = 0.0013 bt | .0565 | .0877 | .1189 | .1501 | .1813 |
| Total Minimum Area for Both Directions = 0.002 bt | .087 | .135 | .183 | .231 | .279 |
*Assumed width, b, = 12 inches