Structural Engineering Slide Library

Cable-stayed bridges

	Image-GoddenC65.1 The Clark Bridge, spanning the Mississippi River at Alton, Illinois, about 20 miles north of St. Louis, Missouri, is a cable-stayed bridge with a 657-ft. navigational main span and two 302-ft. side spans. The 40 cables which drape over two single 283-ft. concrete towers support a 103-ft. wide superstructure consisting of 10.5 inch thick precast concrete panels and a supporting steel frame. The average water depth at the center of the channel is 40 ft. The towers rise 177 ft. above the roadway, and the pilings that support them were driven more than 140 ft. below bedrock. Total length is 4,620 ft. including the 2 approaches. All photos taken from the Missouri side. (Alton, Illinois)
	Image-GoddenC65.2 Each cable is anchored to an edge girder at deck level in a side span, passes over the top of a tower through a stainless steel tube, and is anchored to an edge girder in the center span. This produces a radial arrangement of cables: it is the first such design in the U.S., using single towers and 2 planes of stay cables. The cables consist of 0.6 inch diameter epoxy coated strands arranged in parallel configuration. The full length of each cable is encased in a polyethelene sheath pipe, except for a short length over the tower saddle where a stainless steel pipe is used. (Alton, Illinois)
	Image-GoddenC65.3 Detail of the Clark Bridge showing the top of one tower. Each tower is on the centerline of the deck and is topped with a stainless steel saddle. Each stay cable is continuous between the deck level anchorages rather than being anchored at the tower. This arrangement reduces tensile forces in the towers. Each tower also has 2 transverse cables attached to the top of the tower at each side and at deck level to the end of transverse cantilevers. This photo shows the pair of cables on the near side of the tower. They can also be seen in GoddenC65.1. (Alton, Illinois)
	Image-GoddenC65.4 Detail of Clark Bridge showing the cable anchorages at deck level and a pair of cables anchored to the end concrete frame. Opened to traffic in January 1994, the cable-stayed Alton, Ill. bridge crosses the Mississippi River about 20 miles north of St. Louis, linking Missouri to Illinois on U.S. Route 67. (Alton, Illinois)
	Image-GoddenC65.5 View of the Clark Bridge from a car entering the side span from the Missouri end. This view shows the arrangement of single towers on the centerline of the deck, and the 2-plane radial arrangement of the stay cables. There are 4 traffic lanes and 2 bike lanes. (Alton, Illinois)

Set C: Cable and Suspension Structures