Structural Concrete - Hassoun

Problems 287
7. C. O. Orangum, J. O. Jirsa, and J. E. Breen. “A Reevaluation of Test Data on Development Length and
Splices.” ACI Journal 74 (March 1977).
8. J. Minor and J. O. Jirsa. “Behavior of Bent Bar Anchorage.” ACI Journal 72 (April 1975).
9. American Concrete Institute Detroit (ACI), ACI Code. Building Code Requirements for Structural Concrete.
ACI 318–14. ACI, Detroit, MI, 2014.
PROBLEMS
7.1 For each assigned problem, calculate the development length required for the following tension bars. All
bars are bottom bars in normal-weight concrete unless specified otherwise in the notes.
No.
Bar
Clear
No. f ′ c (ksi) f y (ksi) Cover (in.)
Clear
Spacing (in.)
Notes
a 5 3 60 2.0 2.25
b 6 4 60 2.0 2.50 Lightweight aggregate concrete
c 7 5 60 2.0 2.13 Epoxy coated
d 8 3 40 2.5 2.30 Top bars, lightweight aggregate concrete
e 9 4 60 1.5 1.5
f 10 5 60 2.0 2.5 No. 3 stirrups at 6 in.
g 11 5 60 3.0 3.0
h 9 3 40 2.0 1.5 Epoxy coated
i 8 4 60 2.0 1.75 (A s provided)/(A s required) = 1.5
j 6 4 60 1.5 1.65 Top bars, epoxy coated and no. stirrup at 4 in.
7.2 For each assigned problem, calculate the development length required for the following bars in compression.
No. Bar No. f ′ (ksi) f c y
(ksi) Notes
a 8 3 60
b 9 4 60
c 10 4 40
d 11 5 60 (A s required)/(A s provided) = 0.8
e 7 6 60 (A s required)/(A s provided) = 0.9
f 9 5 60 Column with spiral no. 3 at 2 in.
7.3 Compute the development length required for the top no. 9 bars of a cantilever beam that extend into the
column support if the bars are
a. Straight
b. Have a 90 ∘ hook at the end
c. Have a 180 ∘ hook at the end
The bars are confined with no. 3 stirrups spaced at 5 in. and have a clear cover of 2.0 in. Use
f c ′ = 4ksi and f y = 60 ksi. (Clear spacing = 2.5 in.)
7.4 Repeat Problem 7.3 when no. 7 bars are used.
7.5 Repeat Problem 7.3 when f c ′ = 3ksi and f y = 40 ksi.
7.6 Repeat Problem 7.3 when no. 10 bars are used.