CEE 143 – Design of Prestressed Concrete
University of California at Los Angeles
Spring 2015
Bondy
Homework #1 (Due April 9th)
Problem #1
Find the area, moment of inertia and the top & bottom section modulus for each of the
following sections: (3 pts. – 1 pt. each)
Problem #2
1)
2)
3)
4)
5)
6)
7)
Determine all of the equivalent loads acting on the tendon group and draw them
acting in the correct directions on a “tendon only” diagram. (1 pt)
Verify statics on the “tendon only” diagram (show the sum of forces in the vertical
direction and sum of moments about point “A” are both zero). (1 pt)
Determine all of the equivalent loads acting on the weightless concrete beam and
draw them acting in the correct directions on a “concrete only” diagram. (1 pt)
Verify statics on the “concrete only” diagram (show the sum of forces in the vertical
direction and sum of moments about point “A” are both zero). (1 pt)
Draw the shear diagram and moment diagram (to the tension side) on the “concrete
only” due to the equivalent loads. (1 pt)
Verify that the “concrete only” moment found in Part 5 at the point 35 feet to the
right of “A” is equal to F multiplied by the tendon eccentricity “e” at that location.
(1 pt)
Verify that the “concrete only” moment found in Part 5 at Grid “B” is equal to F
multiplied by the tendon eccentricity “e” at that location. (1 pt)
Homework #1 2015 Solution Summary
Double-Tee
A= 568 in2
I = 46,546 in4
St = 5,254 in3
Sb = 2,011 in3
Box Girder
A= 2,652 in2
I = 3,176,041 in4
St = 59,398 in3
Sb = 74,679 in3
Tee-Beam
A= 1,086 in2
I = 113,496 in4
St = 9,495 in3
Sb = 5,148 in3