# CHANGE IN LENGTH



## Engineer22 (Jan 28, 2018)

*GIVEN*


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## Mithrandir918 (Jan 28, 2018)

What is the change in temperature?


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## Engineer22 (Jan 29, 2018)

T- it is change in temperature.


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## DoctorWho-PE (Jan 29, 2018)

1.17"  IF I understand what you are asking.  How did you do it?


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## ZEZO4 (Jan 30, 2018)

Steel coefficient of expansion is 0.0000065 not 0.000065 (AISC Manual 14th. Ed. P.p 2-39), the answer is 1.17" as *vhab49_PE said.*


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## Engineer22 (Jan 30, 2018)

Can you explain how you got this solution? I multiplied all three: 100 x 150 x Coefficient of Steel, and get .0975.


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## thedaywa1ker (Jan 30, 2018)

Engineer22 said:


> Can you explain how you got this solution? I multiplied all three: 100 x 150 x Coefficient of Steel, and get .0975.


You got 0.0975ft which is 1.17inches.


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## Engineer22 (Jan 31, 2018)

UNDERSTOOD- silly error, on my part, thank you! Could this equation be solved if only the temperature was given? (but not change in temperature)


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## User1 (Jan 31, 2018)

well, with no change in temperature or other status, the material wouldn't change physically


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## Engineer22 (Feb 1, 2018)

Hi TJ- Even if the temperature stayed constant at a very high temperature?


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## kevo_55 (Feb 1, 2018)




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## thedaywa1ker (Feb 1, 2018)

Engineer22 said:


> Hi TJ- Even if the temperature stayed constant at a very high temperature?


If the steel is at a very high temperature, it would have expanded as the temperature rose from 'room temperature'.  Once the temp has risen to say a million degrees, the steel would have been expanding the whole time, but stops expanding once the temp is constant.


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## DoctorWho-PE (Feb 1, 2018)

Engineer22 said:


> UNDERSTOOD- silly error, on my part, thank you! Could this equation be solved if only the temperature was given? (but not change in temperature)


It is an error that will bite you in the butt if you aren't really careful!


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## Engineer22 (Feb 3, 2018)

Haha, understood- both of you, thank you!


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## Engineer22 (Feb 3, 2018)

The coefficient of expansion of steel ----&gt; is this in feet or inches?? (referring to the *.000065 *value)

If one of the factors being multiplied is in feet (150' expansion joint), how does answer result in inches, before converting to feet?


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## StructEngBrah (Feb 4, 2018)

The thermal expansion of steel is .0000065 in/in/deg F. You can find thermal expansion values in any unit you want, it's just important that you are consistent with units.  Check the units for each problem to make sure you are not making a mistake.  The answers you are receiving just converted 150' to 1800" and plugged them into the thermal expansion equation.


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## User1 (Feb 7, 2018)

^ all of this. sorry, I didn't get notification of a response and went a bit MIA. We've got a good crew here!


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## Engineer22 (Feb 11, 2018)

Y'all are fantastic, thanks so much! Very responsive and more helpful than I could have asked for.


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## OHBridgeGuy (Feb 24, 2018)

If it helps, for bridges at least you can assume a setting temperature.  IE if you are using steel in the midwest from the temp figures of AASHTO section 3 you probably have a range of -10 deg to 115 deg (depending on location), then you assume a setting temp, say around 60 degrees.  Therefore you have to consider 70 degrees in fall and 45 degrees in rise.  This is using the method with the figures, there is also the simpler method where you just take the total range, but the figures aren't hard so I usually use them.


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