Quincy, Illinois is rich in both historical and architectural significance. Adding to this distinction is the Bayview Bridge which celebrated its 26th anniversary in August. This bridge is the first city in the country to have a hybrid bridge with its distinctive “H” shaped towers. The Bayview Bridges “H” structure benefits the form work of the geometry so that the cable stays are all on the same plane in addition to being outside the travel lanes. Everything is concentric, unlike a typical suspension bridge in which the suspender cables are all parallel as they drop to hold up the bridge deck. The Bayview Bridge deck is high enough above the river to allow six story high riverboats pass underneath.
The main difference with a cable-stayed bridge is that individual bundles of cables are being anchored to a panel point on the roadway, whereas with a suspension bridge, though they are still spaced-out intersections on the roadway, they just go straight up. The load gets picked up by the main cable which is draped over the towers and anchored on each shoreline for the bridge.
The load path on a cable-stayed “H” bridge is directly connected to the tower. The shape of the bridge is one of the first of its kind anywhere.
The hybrid structure refers to how the road way superstructure is constructed from steel. This portion of the bridge consists of steel floor beams and at the end of those floor beams and at the end of those floor beams is where they’ve anchored the main cables. These cables descend from above and there is a steel anchor assembly on either end at the anchor points. Precast deck panels are also used on the bridge. The hybrid structure offers some weight savings.
Evidence of the soundness and durability of the bridge came when the bridge was tested by one of those notorious one hundred year flood events.
To read the full article visit Slingmakers Issue 140 page 46.