William H. Harsha Bridge Background
While writing the article about Louisville's plan for a new suspension bridge, we came across an interesting page from the company that designed the recently built William H. Harsha Bridge, a cable-stayed bridge that allows truckers to bypass Maysville on US 62/68. The page contains some photos of interesting views of the bridge and some background information of its construction, including 3D animations of the bridge, wind test models, and more. Also included are construction photos showing workers building the massive bridge. It really is an engineering marvel, but don't take our word for it. Check the site out yourself here: American Consulting Engineers
From the Design Specifications:
*Out to out bridge width of 58'-6" with two 12 ft. traffic lanes and two 12 ft. shoulders.
*The main bridge with a total length of 2,100 ft. including two anchor spans with each being 125 ft. long; flanking spans being 400 ft. in length; and the channel span being 1,050 ft. long.
*A 3-span 311'-10" approach bridge on the Kentucky side is also included in the design contract.
*The main cable stayed superstructure consists of a concrete deck supported by two main 84 to 60 inch deep
steel plate girders with floor beams spaced at 16'-8". The deck consists of precast deck sections with cast-in-place joints and post-tensioning in both longitudinal and transverse directions.
*Steel cable stays are a two plane semi harped system with stays spaced at 50 foot intervals along each edge of the deck.
*Two main towers have a goal post configuration with an upper and lower strut. The towers are 332 ft. tall and are supported on 16 concrete filled drilled shafts. Abutments are conventional concrete units supported by steel H piles.
*All Cable Stayed Bridges have had problems with stay wind gallop when the right combination of light rain and wind occur. With this bridge the stay system is state-of-the-art. A co-extruded high density polyethylene pipe has been used which has a brilliant white outer layer eliminating the necessity to use a tape wrap. The outer layer has a small spiral bead around the pipe to break up air flow when there is light rain and wind to help prevent cable gallop. In addition, stay damping cables are connected between the stay cables with soft neoprene collars to further dampen galloping.