Allowable compressive stresses in masonry shall not exceed the values prescribed in Table R606.9. In determining the stresses in masonry, the effects of all loads and conditions of loading and the influence of all forces affecting the design and strength of the several parts shall be taken into account.
ALLOWABLE COMPRESSIVE STRESSES FOR EMPIRICAL DESIGN OF MASONRY
|CONSTRUCTION; COMPRESSIVE STRENGTH OF UNIT, GROSS AREA||ALLOWABLE COMPRESSIVE STRESSESa GROSS CROSS-SECTIONAL AREAb|
|Type M or S mortar||Type N mortar|
|Solid masonry of brick and other solid units of clay or shale; sand-lime or concrete brick:|
|8,000 + psi||350||300|
|Groutedc masonry, of clay or shale; sand-lime or concrete:|
|4,500 + psi||225||200|
|Solid masonry of solid concrete masonry units:|
|3,000 + psi||225||200|
|Masonry of hollow load- bearing units:|
|2,000 + psi||140||120|
|Hollow walls (cavity or masonry bondedd) solid units:|
|2,500 + psi||160||140|
|Stone ashlar masonry:|
|Limestone or marble||450||400|
|Sandstone or cast stone||360||320|
|Rubble stone masonry:|
|Coarse, rough or random||120||100|
For SI: 1 pound per square inch = 6.895 kPa.
- Linear interpolation shall be used for determining allowable stresses for masonry units having compressive strengths that are intermediate between those given in the table.
- Gross cross-sectional area shall be calculated on the actual rather than nominal dimensions.
- See Section R606.13.
- Where floor and roof loads are carried upon one wythe, the gross cross-sectional area is that of the wythe under load; if both wythes are loaded, the gross cross-sectional area is that of the wall minus the area of the cavity between the wythes. Walls bonded with metal ties shall be considered as cavity walls unless the collar joints are filled with mortar or grout.