Distribution

          84
          84    74 
          83    74
          83    73
          82    73
       89 82 79 73 69
    93 89 82 79 72 69
    93 88 82 79 72 69
 99 93 88 82 78 72 68
 99 92 87 82 77 71 67 64
 99 92 86 81 76 71 67 64 59
 96 92 86 81 76 71 67 63 59         39
 96 91 86 81 76 71 66 63 57 54    44 39
 95 90 86 80 75 70 66 61 56 54 49 43 37    23
 95 90 85 80 75 70 66 61 55 51 46 42 35 28 21 

Mean: 72, Median 75

Problem 1

Answers which predicted incorrect magnitudes but correct directions for the vertical reactions received most credit.

Answers which predicted incorrect directions (e.g. answers that could be identified as incorrect simply by looking) received less credit.

Problem 2

This problem could be solved by several methods. The example below shows one based on trigonometric calculations.

The example below shows a geometric approach, which produces an equivalent answer, although it identifies a different location on the object.

Many people correctly calculate the direction and magnitude of the force, but failed to consider the location on the object.

Problem 3

The example below has the following strong points:

• Clearly drawn and labelled graphs, indicating the yield and rupture points.
• Clear explanations which compare the curves and describe the behavior.

Problem 4

A correct answer did the following:

• Clearly drawn shear and moment diagrams with correct shape and values.
• The moment diagram indicates the smooth transition at the endpoints of the distributed load area, and the kink at the point of the concentrated load.
• The free body diagram is clear, and corresponds with the accompanying equations of statics.
• The results of the free body diagram are compared with the shear and moment diagrams.

Problem 5

a) Two answers were accepted for full credit: The loss of ductility which occurs when the concrete becomes the weak link; and the tendency for members with too much prestressing to bend upwards. The second answer is not strictly correct, since it is a problem of too much prestress, rather than too much reinforcing, that is, pulling tendons too tight, rather than having too many tendons), but was close enough to fit the scope fo the problem.

b) The following simple answer goes to the heart of the matter:

c) This question also had a simple answer (although cross referencing was not necessary).

d) There were two basic approaches to correct answers, the most common one being to accommodate movement especially due to temperature. Many answers failed to give a clear explanation of the source of the movement, or of how the roller would help improve the behavior. Another correct answer concerned using rollers to make a structure easier to analyze.