CE473

Partial Exam #2

Full Name:______

PUID:______

This is a closed-book examination. You may use a one-sided equation sheet (letter size), but no other references. No examples or explanations shall be included in your equation sheet.

You may not use electronic devices capable of running commercial software (such as Excel or MathCad).

Document your calculations thoroughly. State all assumptions. Unexplained work will receive no credit. Illegible work will received no credit.

You have two hours to complete the examination. Turn in your solution, your copy of the exam questions, and your equation sheet.

See the last page for design aids.

BOX answers

Staple all pages

Number all pages

Write your name on all pages

Use a reasonable number of significant figures

Problem 1

The figures below describe a reinforced concrete specimen to be tested at Bowen Laboratory. The assembly shown is to be loaded with a lateral load acting along the longitudinal axis of the top beam. Assume that the top and bottom beams are rigid. The top beam is free to move in the direction of the load, but it is restrained against rotation. The bottom beam is restrained against rotation and translation. Compute:

1) the immediate deflection caused by a concentrated load of 10kip (D1).

2) the immediate deflection caused by a concentrated load of 30kip (D2).

3) Should the ratio D2/D1 be equal to 3? Explain in ONE sentence.

Assume f’c = 7000psi, fy = 60ksi. Ignore tensile stresses in concrete. You may ignore the effect of compression reinforcement on depth to the neutral axis and curvature in the linear range of response.

Loading and Boundary ConditionsSection AA

Reinforcement Layout

Problem #2

A beam with the cross section shown is to be designed as a water conduit. The beam is made with concrete and reinforcing steel with the following properties:

f’c = 3500 psi

fy = 80,000psi

a) Estimate the maximum amount of tension reinforcement that can be provided in this section according to current design recommendations.

c) Estimate the nominal moment capacity and curvature at nominal capacity for the amount of steel computed in question a)

Problem #3

Compute the nominal moment capacity and limiting curvature of the cross section shown. Assume:

f’c = 3000 psi

fy = 60,000psi

Do not ignore the 2-in hole.

Problem #4

a)Circle the section likely to have larger strains in the steel (an therefore wider flexural cracks) for similar service conditions, cross-sectional dimensions, and material properties.

b)Circle the section likely to have a deeper neutral axis for similar service conditions, cross-sectional dimensions, and material properties.

c)Circle the section likely to have larger additional deflections caused by shrinkage for similar loading, cross-sectional dimensions, material properties, and environmental conditions.

d)Circle the section likely to have larger additional deflections caused bycreep for similar loading, cross-sectional dimensions, material properties, and environmental conditions.

e)Circle the section likely to have to larger additional deflections caused by shrinkage for similar loading, cross-sectional dimensions, material properties, and environmental conditions.