Page 272 - Design of Reinforced Masonry Structures

DESIGN OF REINFORCED MASONRY BEAMS 4.135

4.8 A nominal 8 × 24 in. concrete masonry beam is reinforced with one No. 5 Grade
60 bar at an effective depth of 20 in. (Figure P4.3). Determine the moment capacity
φM of the beam. Assume ′ f = 1500 psi.
n m
4.9 Determine the moment capacity, φM of the beam described in Prob. 4.3 if Grade
n
40 reinforcing bar were to be used instead of Grade 60 bar. All other data are the
same.
4.10 A two-wythe 8 × 24 in. clay brick beam has an effective depth of 20 in. It is
reinforced with one No. 7 Grade 60 bar for tension. (Fig. P4.10). Determine the
moment capacity, φM , of this beam. ′ f = 2000 psi. Portland cement Type S
n m
mortar would be used for construction.

8"

20"
24"

1#7
FIGURE P4.10

4.11 Using Eq. (4.43), (a) determine the flexural strength, φM , of the beam described
n
in Prob. 4.3; (b) How would the flexural strength of the beam be affected if
Grade 60 bar were replaced with a Grade 40 bar?

One-legged
stirrups

Tension
reinforcement

FIGURE P4.11