TM 5-809-3/NAVFAC DM-2.9/AFM 88-3, Chap. 3
9-6. Design Example. The following design example illustrates a procedure for designing reinforced
masonry pilasters. The design of reinforced masonry columns is very similar and will follow the same
procedure except that stability in both directions must be considered in column design.
a. Given.
(1) Truss end reaction (P) = 40 kips
(2) Eccentricity (e) = 2 inches.
(3) Height of pilasters (h) = 16 feet
(4) Spacing of pilasters = 25 feet
(5) Lateral wind load on wall (w) = 20 psf
(6) The wind loading, w, acts both inward and outward.
(7) Masonry:
Type S mortar
f*m = 1350 psi
Fm = 0.33f*m = 450 psi
Em = 1000f*m =1,350,000 psi
(8) Reinforcement:
fy = 60,000 psi
Fs = 24,000 psi
Es= 29,000,000 psi
(9)
b. Problem. Determine the pilaster size and vertical reinforcement.
c. Solution. The pilaster must be designed to resist the given eccentric axial load in combination with the
lateral wind load. The design must be checked at the top and at the mid-height of the pilaster to determine
the critical section. The design procedure is to select an economical pilaster cross section and check the
selected section for the required loading conditions.
(1) Assumptions.
(a) The wall spans horizontally between pilasters and all lateral loading on the wall is transferred
to the pilasters.
(b) The pilasters are pinned at top and bottom.
(c) The initial pilaster cross section will be 16 inches by 16 inches with 6-#9 vertical bars as shown
in figure 9-7.
(2) Check the minimum and maximum reinforcement requirements.
As = The area of reinforcement, in2
= 6(1.00 in2) = 6.00 in2
Ag = The gross area of the pilaster, in2
= bt
Where:
b = The actual width of the pilaster = 15.62 in.
t = The actual thickness of the pilaster = 15.62 in.
Ag = (15.62 in)(15.62 in) = 244 in2
9-8
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