Bridge Inspections For A Safer Infrastructure
Cable Stay Bridge Construction Explodes in US.December 17th, 2018 Author: Doug Thaler
Cable stay bridges are some of the most visually appealing bridges for new bridge construction.
Not only are they visually appealing but for medium length bridges they are more cost effective, require fewer materials and are typically constructed faster than competing bridge types.
North of New York the Tappan Zee bridge which spans the Hudson at the second widest point was commissioned in 2012. The three competing companies all submitted designs for cable stayed bridges. The old bridge was costing over $50 million in maintenance a year and the new bridge with a cost of over $3.9 billion stretches five kilometers across the Hudson.
The bridge was built to last 100 years, twice that of its predecessor.
The New Harbor bridge in Corpus Christie Texas will be the longest Cable Stayed Bridge when construction is completed in 2020. The bridge will carry Route 181 across the Corpus Christi Ship Channel replacing the current bridge that was built back in 1959.
The approaches, according to the designers, will be constructed with long spans in order to reduce the number of piers necessary by 25 percent. Concrete piers will be “slender,” according to the plans, in order to reduce the approaches’ footprint.
The New Harbor bridge main span length of 1,661 feet will surpass Louisiana’s John James Audubon Bridge as the longest cable-stayed bridge in the country. The main tower will be 538 feet tall and will make it the tallest structure in South Texas.
Additional bridges choosing cable stay designs are located in Greenville, Miss., Louisville, Ky., and Tacoma, Wash.—Civil engineers are choosing cable-stay designs over others as they update the nation’s aging infrastructure.
Tacoma cable-stayed bridge over Thea Foss Waterway
A Venetian inventor Fausto Veranzio were the first known drawings of a cable stayed bridge dating back to 1595.
Early suspension bridge plans near Bangor Wales completed in 1826. In 1801 James finley built the first one in the western world in PA.
The closest type of bridge to the cable-stayed bridge is the suspension bridge.
The difference between the two is primarily in the cables. In the suspension structure like the Golden Gate Bridge the main primary cables are strung from tower to tower and there are secondary cables that drop down from those towers to hold the roadbed in place. Cable-stayed bridges, in comparison, have cables that run directly from the tower to the road. They essentially eliminate the cables between towers.
Golden Gate Bridge
Bratone Cable Stayed Bridge France
Engineers first choice today when designing a bridge to carry traffic provided that the longest section of road deck to be installed ranges between 150 and 915 meters is a Cable Stayed Bridge. At these lengths the thinner deck and minimalist pattern of cable-stays almost always beats out the alternatives in cost, time and material savings.
Cable-stay is inadvisable for bridges with a main span longer than 915 meters because the towers would have to soar twice as high as the towers of a suspension bridge of the same length to string enough cables to hold the road deck in place. For very long bridges, traditional suspension wins out.
The longest strip of road to be lifted into place on the New NY Bridge will be 365 meters.
Cable-stayed bridges debuted relatively recently in the U.S., even though they’ve been in vogue elsewhere for hundreds of years. An engineer named Arvid Grant built one of the first cable-stayed bridges in the U.S. across the Columbia River in Washington State between Pasco and Kennewick in 1978.
Grant was trained in Europe, where bridge-builders had been honing cable-stayed methods for decades and where the one of the earliest modern bridges using this design was erected in Sweden in 1955.
Here in the U.S. a French engineer named Jean Muller completed another major cable-stay project, the Sunshine Skyway Bridge in Saint Petersburg, Fl., in 1987. Improvements in stress tolerance, corrosion resistance and computer modeling around the same time helped their popularity grow as engineers built them cheaper and more efficiently.
By locating early stage deterioration and properly maintaining & conducting repairs the service life of our critical infrastructure assets can be extended and untimely replacements