Page 260 - Masonry and Concrete

Masonry Veneer

259
MASONRY VENEER

the wall above its entire length (Figure 7-12). When arching action is
assumed, the lintel requires temporary support until the mortar has
cured sufficiently to allow the masonry to assume its share of the load.
Arching action produces an outward horizontal thrust at each sup-
port or abutment. The abutments, therefore, must have sufficient mass
to resist this force. If the opening is near a corner or close to another
opening, or if an expansion or control joint occurs at the side of the
opening, it may again be necessary to size the lintel large enough to
carry all of the loads above its entire length, without assuming any
arching action in the masonry. Once the total load on the lintel is
known, it can be appropriately sized by an engineer to resist the cal-
1
culated stresses. Lintel deflection should be limited to 600 of the span
to avoid cracking the masonry.
Steel angles are the simplest lintels to use for masonry veneers and
are suitable for openings of moderate width such as windows and
doors. For wider openings such as garage doors, double lintels or steel
beams with suspended plates may be required (Figure 7-13). The hori-
zontal leg of a steel angle should be at least 3 in. wide to adequately
support a nominal 4-in. wythe of brick, block, or stone. Generally,
1
angles should be a minimum of 4 in. thick to satisfy code require-
ments for exterior steel members. Precast concrete, reinforced masonry,

LOAD

COMPRESSION
TENSION

SHEAR SHEAR

FIGURE 7-9

Tension, compression, and shear loads in lintels.

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