Page 242 - Design of Reinforced Masonry Structures

DESIGN OF REINFORCED MASONRY BEAMS 4.105

0.30

Support
e = 1/20
0.25

1/10
T in terms of w 2l (single spans) T in terms of wl (continuous spans) 0.15 Midspan 1/5
0.20

0.10
1/20 and 1/10
1/5
Midspan and support, e = 1/2
0.05

0
0 0.2 0.4 0.6 0.8 1.0
Height to span ratio–b
FIGURE 4.29 Determination of resultant T for Example 4.28 [4.18].

From Fig. 4.29, find coefficient for T, resultant of tensile stresses, and multiply by
w2l (for single-span beams), where w = load on wall per linear foot.

T = (0.095) (w2l)
= (0.095) (2500) (2) (24)
= 11,400 lb

Calculate the area of tension reinforcement:
,
A = T = 11 400 = 048 in.
2
.
s
,
F 24 000
s
Select one No. 7 bar,
2
2
A = 0.6 in. > 0.48 in. OK
s
Assume that reinforcing bar is located near the bottom of beam, d = (24) (12) − 4 =
284 in.