Bridge Falls onto I75
In Chattanooga the I75 southbound overpass wall fell onto the I75 underpass to I24 westbound. All I75 traffic is stopped until furtur notice at that point. I dare say that I75 South will be closed fo...
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I'm re-habbing some simlar bridges right now, cast in place box beams from the 60s.
Deck is cast in place but integral to the box and the bottom slab is also partially rotten. Trapped moisture and rotting trapped lumber inside the box from forming the box beams.
Note no access hatches in the bottom and likely no pour back in the top. Formwork gets left inside and holds moisture causing sever corrosion once the water gets into the concrete.
I'm strengthening the bottom of the webs on the ones I'm re-doing right now. Carbon fiber strips applied longitudinally along the under the webs. To keep this from happening. Strengthens the tensile value of the bottom flange and bottom of box soffit.
That's my CSI rvnet root cause analysis. $20 says the cause was corrosion and extra dead load (asphalt overlays and possibly the barrier).
Bridges I'm doing right now still have traffic on them until we get the temp bridges finished, but once we start deck rehab, the FRP strengthening on the bottom needs to be done before construction loads are allowed and can only work 1 5' wide strip at a time. So ours don't end up in the river like this!
Deck is cast in place but integral to the box and the bottom slab is also partially rotten. Trapped moisture and rotting trapped lumber inside the box from forming the box beams.
Note no access hatches in the bottom and likely no pour back in the top. Formwork gets left inside and holds moisture causing sever corrosion once the water gets into the concrete.
I'm strengthening the bottom of the webs on the ones I'm re-doing right now. Carbon fiber strips applied longitudinally along the under the webs. To keep this from happening. Strengthens the tensile value of the bottom flange and bottom of box soffit.
That's my CSI rvnet root cause analysis. $20 says the cause was corrosion and extra dead load (asphalt overlays and possibly the barrier).
Bridges I'm doing right now still have traffic on them until we get the temp bridges finished, but once we start deck rehab, the FRP strengthening on the bottom needs to be done before construction loads are allowed and can only work 1 5' wide strip at a time. So ours don't end up in the river like this!
