Format and Objectives

The chief objective is to learn by doing and explaining to others, and to clarify misunderstanding as soon as possible, so that it does not accumulate. Work on problems in pairs, and ask the TA or another pair if you have a question about a problem. For lab number 1, the problems will not be collected. Credit for the lab will be based on attendance and participation.

Pre Lab Exercise

Closely examine the 14th street bridge. Look at it from below and think about how the framing transfers loads from the tracks to the bridge end supports. Ask yourself questions about why the framing is configured as it is.

Bring to the lab meeting a free body diagram of the east girder of the bridge (the large black beam that faces toward the med center). Draw the girder to approximate scale and draw all the forces acting on it. Since it is a free body diagram, the drawing includes only the girder and nothing else: no supports, no other framing, etc. The forces should include the following:

• The forces exerted on the girder by the framing of the bridge deck.
• The forces exerted on the girder by its supports.
• The self weight of the girder.

Don't worry about the magnitudes of the forces acting on the girder or the exact dimensions. Indicate the forces as they are actually applied rather than as simplified resultants. Draw the diagram on a single 8.5x11 sheet of paper and hand it in at the beginning of the lab session. The sketches will be collected and recorded during the lab meeting.

Problems

Force systems:	1.1.3, 1.1.9
Center of Gravity:	1.1.13