Thursday, August 9, 2012

Niigata, Japan's Bridges: Toyota Bridge on Route 8

August 2007 (37.389 Degrees, 138.592 Degrees) Toyota Bridge
We traveled north on the Horukiru Toll Road and then turned south on National Highway 8.  At first we traveled through a lot of landslides and road damage (see below) until we arrived at two bridges carrying Highway 8 over the Sabaishi River in Kashiwazaki. 
The older bridge (not shown) is on the old highway alignment where the embankments have settled about 1/2 meter due to lateral spreading. Sand and asphalt have been placed to allow traffic back onto the bridge.  The new Toyota Bridge has a 3 span continuous steel (highly skewed and curved) I girder superstructure on seat-type abutments and single column bents.  The deck is 160m long with a 12m width and is supported on tall elastomeric bearings with transverse shear keys and concrete backwalls to limit movement.  The embankment behind abutment #1 (on the west end of the bridge) is supported by mechanically stabilized retaining walls. A rigid box structure allows access through the settled embankment (see below). 
During the earthquake the riverbanks moved toward the river and the embankments settled about 0.3 meters. The abutments moved closer to each other and the superstructure moved to the northwest. As a result of all this movement, there was some pounding between bridge components and the elastomeric bearings experienced quite a bit of shear. I can't remember why the abutment seat (in the top photo) is so much bigger than the superstructure, but I assume that they are eventually going to widen the bridge.

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Niigata, Japan's Bridges: Toyota Bridge on Route 8 by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

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