Masonry Magazine August 1978 Page. 11
TABLE 1
Rational Design
Assumed Compressive Strength of Brick Masonry
Assumed Compressive Strength of Brick Masonry f'm, psi (MPa)
| Compressive Strength of Units, psi (MPa) | Without Inspection | With Inspection |
|---|---|---|
| | Type N Mortar | Type S Mortar | Type M Mortar | Type N Mortar | Type S Mortar | Type M Mortar |
| 14 000 plus (96.527 plus) | 2 140 (14.755) | 2 600 (17.926) | 3 070 (21.167) | 3 200 (22.063) | 3 900 (26.890) | 4 600 (31.716) |
| 12 000 (82.737) | 1 870 (12.893) | 2 270 (15.651) | 2 670 (18.409) | 2 800 (19.305) | 3 400 (23.442) | 4 000 (27.579) |
| 10 000 (68.948) | 1 600 (11.032) | 1 930 (13.307) | 2 270 (15.651) | 2 400 (16.547) | 2 900 (19.995) | 3 400 (23.442) |
| 8 000 (55.158) | 1 340 (9.240) | 1 600 (11.032) | 1 870 (12.893) | 2 000 (13.790) | 2 400 (16.547) | 2 800 (19.305) |
| 6 000 (41.369) | 1 070 (7.377) | 1 270 (8.756) | 1 470 (10.135) | 1 600 (11.032) | 1 900 (13.100) | 2 200 (15.168) |
| 4 000 (27.579) | 800 (5.516) | 930 (6.412) | 1 070 (7.377) | 1 200 (8.274) | 1 400 (9.653) | 1 600 (11.032) |
| 2 000 (13.790) | 530 (3.654) | 600 (4.137) | 670 (4.620) | 800 (5.516) | 900 (6.205) | 1 000 (6.895) |
TABLE 2
Rational Design
Lateral Support Ratios (h/t) For
Non-Loadbearing, Non-Reinforced Brick Masonry Walls"-b
| Design Wind Pressure, psf (kPa) | Without Inspection | With Inspection |
|---|---|---|
| | Vertical Span | Horizontal Span | Vertical Span | Horizontal Span |
| | N Mortar | S or M Mortar | N Mortar | S or M Mortar | N Mortar | S or M Mortar | N Mortar | S or M Mortar |
| 5d (0.239) | 31 | 35 | 44 | 50 | 38 | 43 | 54 | 61 |
| 10 (0.479) | 22 | 25 | 31 | 35 | 27 | 30 | 38 | 43 |
| 15 (0.718) | 18 | 20 | 25 | 29 | 22 | 25 | 31 | 35 |
| 20 (0.958) | 15 | 18 | 22 | 25 | 19 | 21 | 27 | 30 |
| 25 (1.197) | 14 | 16 | 20 | 22 | 17 | 19 | 24 | 27 |
| 30 (1.436) | 13 | 14 | 18 | 20 | 15 | 17 | 22 | 25 |
| 35 (1.676) | 12 | 13 | 16 | 19 | 14 | 16 | 20 | 23 |
| 40 (1.915) | 11 | 12 | 15 | 18 | 13 | 15 | 19 | 21 |
| 45 (2.155) | 10 | 12 | 14 | 17 | 13 | 14 | 18 | 20 |
| 50 (2.394) | 10 | 11 | 14 | 16 | 12 | 14 | 17 | 19 |
h = clear span (height or length) between lateral supports
t = actual wall thickness
For cavity walls having wythes of equal thickness and built with the same units and mortar, the value of t shall be taken as 1.41 times the actual thickness of one wythe. For other cavity walls, the wind pressure shall be assumed to be distributed to the wythes according to their respective flexural rigidities and then each wythe shall be designed separately.
For design wind pressure, see applicable building code requirements or ANSI A58.1-1972, "Minimum Design Loads in Buildings and Other Structures."
Ratio given for a design wind pressure of 5 psf are only applicable to partitions.
Note: This table is based on the following assumptions: simply supported walls without any openings or other interruptions; and allowable flexural tensile stresses increased by 331/3% for wind. The weight of the wall was neglected.