Thermal Stresses

As you know, I have been trying to figure out how we can configure this bridge to accommodate temperature changes. My current idea is for each of the two spans to have three pins (actually bearings that allow rotation). The connections between the deck and columns would require elastomeric bearings. Here's a sketch to explain what I am talking about. Note that the middle pin (spherical bearing) can be located anywhere along the span and not necessarily at mid-span.




I ran a few different scenarios that lead me to this conclusion.

This scenario shows that thermal loads overstress the no-pin deck, even when the columns are free to slide horizontally.


This scenario shows that thermal loads overstress the no-pin deck, even when there are no columns to further restrain it.


This scenario shows that thermal loads cause high stresses in the two-pin deck, even when there are no columns to restrain it.


This scenario verifies that thermal loads do not cause any stress in the three-pin deck.


This scenario shows that the transverse movement at center span of the 3-pin deck due to a 20 degree C temperature change is about 17 mm.