Steel Footing on the Interstate Highway 35W Bridge (the one that collapsed over the river in 2007) These gear-like bearings show how the bridge could move as the temperature rose and the bridge expanded, the bridge would ride along the gears.
minor clarification-- The actual roller bearings are the round cylinders that are just barely visible beyond each gear. The gears & racks will see no actual loads but are there to keep the ends of the bearing from getting miss aligned during travel.
That circular portion above the rollers (between the gussets) is called a pot bearing which accommodates the live load (deflection caused by traffic) for the bridge.
minor clarification--
ReplyDeleteThe actual roller bearings are the round cylinders that are just barely visible beyond each gear. The gears & racks will see no actual loads but are there to keep the ends of the bearing from getting miss aligned during travel.
That circular portion above the rollers (between the gussets) is called a pot bearing which accommodates the live load (deflection caused by traffic) for the bridge.