Bridge Lab Questions

 

Question 1:

For problem #1, is the sketch suppose to be similar to the PNG image "Truss Chord Diagram with Strain Gages"? 

Response 1

The intent of this sketch is to locate where the strain gauge is located along the length of the bridge rather than where it is on the chord member.

 

Question 2:

For problem #2, do we find the minimum or maximum strain gage value (-33.79ue or 5.55ue for sensor 1)? 

Response 2:

I assume you are referring to part #5 in lab description.  It asks you to figure out whether you expect the strain gauge gets shorter or longer on the top chord (compression or tension).  The answer to that question gives you which value is appropriate.

 

Question 3:

For problem #4 and 5, Is the circled location correct for the strain gage? 

 

Response 3:

This is part of your challenge: to interpret the drawings.  The information circled is true between U7 and U9.  Is that where you think you were?

Note that the data description page also provides location information in terms of percentage along the span..

For those who weren’t certain, the strain gauge was located in the first span after the bascule on the New Jersey side.

Question 4:

For problem #7, we assumed the units for the strain was in micro strains (10^-6). Can you comment if that is correct?

Response 4:

Yes, the “ue” indicates micro strains as you indicate.