Thermal Movement in Concrete/Steel Curved Composite Structures

[graduatequestions]

Is there a difference in how a curved section of a bridge reacts to temperature change as oppossed to a straight section?

If the bearings are articulated to allow movement around the curve does it effectively behave in the same way...?

 

[youngstructural]

Effectively yes, however you must remember that this is a longitudinal problem with a radial component...

Your inside radius can be thought of as a "short" line expanding and contracting, while your outside radius is a "long" line expanding and contracting. This leads to a radial expansion in addition to the tangential expansion and you need to consider this in some cases.

Typically you need to ensure that the slight lateral/tangential movement will be compensated for in the design, normally by having bearings able to accomodate these forces.

Your expansion joint need only be designed for the longitudial forces (along the line of the circumference), but for a differing amount of expansion for the inside and outside.... This is difficult, and typically means (at least in each case I've seen) that these curving bridges are designed as simply supported spans...

Good luck!

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[graybeach]

I have always oriented the expansion bearing for each girder along a chord from the fixed bearing.

 

[SlideRuleEra]

Years ago I had thermal expansion explained to me as an exact analogy to enlarging a photograph - everything expands proportionally. One of the best examples is what happens to a hole in a solid structure. The diameter of the hole increases as temperature rises. It is easy to mistakenly think that the diameter would decrease.

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