NAME:
Structures Spring 2007
First Exam
Questions 1-10 are worth 2 points each, with no partial credit given. Please indicate the best possible answer in each case.
1. The weight of the snow on top of a building is classified as a
A) Dead load
B) Dynamic load
C) Live load
D) Resonant load
E) None of the above
2. A connection that can rotate in one dimension and translate in one dimension is called
A) Free
B) Fixed
C) Pinned
D) Roller
E) None of the Above
3. A motionless horizontal board weighing 12 pounds hangs from two ropes as shown. One rope is attached at one end of the board, while the other is attached in the middle of the board. What is the tension in each of the two ropes?
A) 6 pounds in each
B) 8 pounds in the middle, 4 pounds at the end
C) 9 pounds in the middle, 3 pounds at the end
D) 12 pounds in each
E) 12 pounds in middle, zero at end
4. The drawing shows a series of sandbags, suspended one from the other by cables and attached to the ceiling at the top. In which cable is the tension greatest?
A) The top cable
B) The middle cable
C) The bottom cable
D) The tension is the same for all three cables
E) It depends on the thickness of each cable
5. Look at this truss system. Which of the labeled pieces is in tension?
A) A
B) B
C) C
D) D
E) E
6. In the figure below, line “c” bisects the base of the triangle. The center of mass of the triangle is located along line
A) a
B) b
C) c
D) d
E) e
7. Who patented the geodesic dome?
A) Buckminster Fuller
B) Frank Lloyd Wright
C) I.M. Pei
D) Santiago Calatriva
E) Thomas Edison
8. Identical weights are suspended from 4 sets of cables, which make different angles with respect to vertical. Which set of cables has the most tension?
A) All of these cases will have the same tension.
B) B
C) C
D) D
E) E
9. A cube 5 feet on a side is just barely supported by a short steel post which is 4”x 4”. To support a cube 10 feet on a side (which is made of the same material), how large should the post be?
A) 4”x 4”
B) 6”x 6”
C) 8”x 8”
D) 11”x 11”
E) 16”x 16”
10. To generate the strongest possible columns, which of the shapes shown should be used as the cross-section?
A) A
B) B
C) C
D) D
E) E
Questions 11-16 are worth 5 points each, with partial credit given. Answer each question with a short paragraph or list. You may include equations or drawings if it aids your explanation.
11. Name one famous ancient structure and one famous modern structure.
12. Explain the middle third rule, and its importance to concrete structures.
13. What are the four necessary components of a cable stayed structure? Explain each briefly.
14. Are all of the members in a space frame identical? Explain why or why not.
15. If a column is loaded with too much weight, it will fail. Explain how this failure will occur. Outline different cases if necessary.
16. A man is carrying a long, horizontal ladder over his head. The ladder is 12 feet long and weighs 10 pounds. The man is holding the ladder in two places; 2’ from one end, and 4’ from the same end. What force is each arm exerting (give both a number of pounds and a direction)?