Masonry Magazine June 1976 Page. 14
There is no additional reduction factor for bending moments, as is provided for in the 1969 BIA Standard, Building Code Requirements for Engineered Brick Masonry. If moments of this type are present, the actual stresses (axial and bending) must be compared to the allowable stresses, as shown in the following formulas, and the proper wall section provided:
fafo
Fa F
and
1
(926.7 C) were experienced on the fire exposed faces of the walls.
The test was conducted with a 25,000-lb axial compressive load on the wall. After the fire test was completed, cold water was hosed on the hot wall. The walls successfully met the hose stream test requirements consistent with the fire endurance time.
where:
fa
= actual axial compressive stress,
Fa
= allowable axial compressive stress (see Table 1).
= actual bending stress.
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F
= allowable bending stress (see Table 1).
= allowable flexural tension (see Table 1).
F
Shear Strength. Shear strength is the ability of a wall or assemblage to resist the lateral shearing forces occurring within the plane of the member. Two methods of testing have been used. During the early stages of structural testing of high-bond masonry, the standard ASTM E 72 Racking Test (see Fig. 6) was used. However, in this method, the hold-down rods which are required to prevent overturning of the specimen produce an indeterminate normal load, thus preventing an analytic determination of the state of stress within the wall specimen itself. To correct this, a diagonal tensile test is used in which a 4-ft square masonry panel is loaded on one diagonal to produce a condition of pure diagonal tension and thus measure the shear capacity (see Fig. 4). This test method is ASTM E 519. See Table 1 for allowable shear stresses.
Service Performance Characteristics. In addition to the information on structural stability gained from the previously discussed testing, it was important to obtain information about other performance characteristics of such masonry wall assemblages. Therefore, additional investigations were performed on Sarabond mortar brick masonry assemblages by The Dow Chemical Company, the National Bureau of Standards and the Brick Institute of America to verify and determine these performance characteristics.
Fire Resistance. In an independent laboratory, test walls built with Sarabond brand mortar additive were subjected to the standard fire test in accordance with ASTM E 119. Two 4-in. high-bond masonry walls, one insulated and the other uninsulated, were tested, and both exceeded the required 1-hr rating. The insulated wall had an ultimate fire endurance period of 1 hr and 37 min. This rating reflects the time required to obtain an average temperature rise of 250 F on the unfired side. Temperatures in excess of 1700 F
FIG. 4
Diagonal Shear Test
At the conclusion of the test, an axial compressive load of 200,000 lb (maximum test frame capacity) was applied without wall failure. From these tests it is evident that Sarabond performs equally as well as conventional mortar with respect to fire endurance.
Water Penetration. Resistance to water penetration through a masonry wall becomes increasingly important as wall thicknesses are decreased. Because of the higher density of the Sarabond mortar, reduction in cracking and greater bonding strength, this mortar will perform equally as well as or better than conventional mortar with the same quality of workmanship.
These results were experienced in test walls subjected to simulated conditions of a five-day rainfall of 5.5 in. per hr driven by a 50-mph wind.
Wet Strength. Another important consideration for modified mortars is their flexural strength after expo-