TM 5-809-3/NAVFAC DM-2.9/AFM 88-3, Chap. 3
(4) Summary: The 8-inch x 8-inch CMU lintel reinforced with 1-#4 bar is sufficient.
b. Design example 2.
(1) Given.
(a) 8-inch CMU loadbearing wall
(b) Wall height = 14 ft
(c) Uniform dead load (wDL) = 100 plf
(d) Uniform live load (wLL) = 250 plf
(e) Concentrated live load (P*) = 5000 lbs
(f) f'm = 1350 psi
(g) Fm = 1/3f'm = 450 psi
(h) Em = 1000f'm = 1,350,000 psi
(i) Type S mortar
(j) Reinforcement:
fy = 60,000 psi
Fs = 24,000 psi
Es = 29,000,000 psi
(k)
(l) A door 12 ft wide by 10 ft high is located in the wall as shown in figure 8-4.
(m) Assume the wall above the lintel is reinforced vertically at 32 in o.c.
(n) There is a continuous 8 inch bond beam at the top of the wall.
(o) The concentrated live load, P*, is located 7 ft to the right of the centerline of door.
(2) Problem. Design the lintel to support the given dead and live loadings.
(3) Solution. Since the loading is applied below the apex of the triangle (see figures 8-1 and 8-4),
arching action cannot be assumed. The lintel must be designed for the full applied dead and live loading
above.
Lintel Depth Determination.
(a) The lintel depth will be determined so that shear reinforcement is not required. To establish
the dead loading, assume a lintel depth of 24 inches.
(b) The lintel loadings are as follows:
8-6
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