Structural Concrete - Hassoun

318 Chapter 8 Design of Deep Beams by the Strut-and-Tie Method
Example 8.4 ACI Method
A simply supported deep beam with an opening, shown in Figure 8.22, has a clear span equal to 12 ft,
a total height equal to 6 ft, and a width of 18 in. The beam supports an 18 in. - square column at
midspan carrying a service dead load of 300 K, and a live service load of 240 K. f ′ c = 4ksi,f y = 60 ksi,
Es = 29 * 106 psi.
18"
C
24"
24"
24"
A
E
18.0"
18"
Figure 8.22
42" 60" 42"
18"
Example 8.4: Idealized deep beam with an opening.
1. Calculate the factored loads:
2. Check if beam is deep beam according to ACI Code, Section 9.9, l n = 12 ft, h = 6 ft.
3. Calculate Maximum Shear Strength:
4. Select Truss Model:
See Figure 8.23
5. Calculate Element Forces:
6. Calculate Effective Strength:
Struts connect to all nodes therefore, 2.55 ksi controls to all nodal zones.
7. Design Nodal zones:
Nodes A, E (Figure 8.24)
Nodes C see (Figure 8.24)
Nodes B, E (Figure 8.24)
Design Horizontal and Vertical reinforcement:
Suggest No. 5 bars @ 12 in.
Vertical Bars below opening
Horizontal Bars below opening
Vertical Bars above opening
Horizontal Bars above opening