Reinforced concrete design Name ________________________________

School of Architecture and Design Student ID ___________________________

Architecture 312‐M21 Spring 2016 Date __________________________________

Reinforced Concrete Design

MIDTERM EXTRA CREDIT

Maximum 10 points added to Midterm grade.

Beam Design

Using the following information about a beam cross section

ܾ ൌ 8 in # 3 bar: As = 0.11 in2, db = 0.375”

݀ ൌ 12 in # 4 bar: As = 0.19 in2, db = 0.5”

݄ ൌ 15″ # 6 bar: As = 0.44 in2, db = 0.75”

݂௬ ൌ 60,000 psi # 7 bar: As = 0.6 in2, db = 0.875”

݂ᇱ ൌ 3,000 psi Concrete cover, cc = 2”

1) Calculate the factored distributed load, ݓ௨

2) Calculate the design maximum bending moment, ܯ௨

3) Calculate the design maximum shear, Vu

4) Determine the required area of reinforcing steel, ܣ௦, for bending design

5) Perform the bending design “checks”

a. Is ߶ܯ ܯ௨?

b. Is ܣ

௦ ܣ௦,?

c. Does the reinforcing steel meet minimum spacing requirements?

d. Does the beam meet the strain requirements? (At ߝൌ 0.003, is ߝ௦ 0.005?)

6) Calculated the factored concrete shear capacity, capacity ߶ܸ .

a. Is shear reinforcing required? (Is 0.5߶ܸ ܸ ௨? ሻ

7) Determine the required shear reinforcing, Av, and spacing, s (make sure you do not exceed

smax)

wD = 750 lbs/ft (including self wt); wL = 500 lbs/ft

= 15 ft.

Arch 312‐M21 MIDTERM EXAM Student ID ___________________

Arch 312‐M21 MIDTERM EXAM Student ID ___________________

For the problem, please be careful with units. Distributed loads (wu) should have units of lb/ft or k/ft. Moments (Mu, Mn) should have units of lb-ft, lb-in, k-ft, or k-in. Shear (Vu, Vc, Vs, Vn) should have units of lbs or kips. When solving the problem make sure that units in any formula you use are consistent. Many of you also confused expressions with square roots (srt(f’c)). Whenever you take the square root of f’c, both f’c and its square root have units of PSI. You cannot use ksi in the radical.

Lastly, be as thorough as you can with showing your work and the design and checks that you do. For calculating As, if you “guess” reinforcing, you need to conduct iterations if its more than required. Otherwise, you can solve the quadratic like we did in class (I recommend this method – I swear its quicker!). I like to give partial credit when you are on the right track with problems, but will be more critical with this problem since it is extra credit.

Here is picture of What we did in class:

https://www.dropbox.com/sh/59nx34u721300f6/AADfykQkX1vvNybySWFyWUW7a?dl=0

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