| Name | Brooklyn Bridge, New York |
|---|---|
| Who | |
| Owner | New York City Department of Transportation |
| Design | John A Roebling and Washington A Roebling |
| Contractor | |
| Where | New York City |
| Latitude | N 40 42' 21" |
| Longitude | W 73 59' 48" |
| When | A New York icon and the oldest of NY City's East River bridges - opened in 1883. Designated a Historic Landmark in 1967 |
| Why | Connects Manhattan to Brooklyn and Long Island over East River |
| What | Read more..... |
| How to read the bridge | Read more..... |
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| What | |
|---|---|
| Overall type | Hanging - has suspension cables and stays. The first time steel wire was used for suspension cables. |
| Width | 26 m. |
| Length | 1825 m. |
| Main span | 486.3 m. with side spans 283.5 m. |
| Height of tower | 4.28 m. above water level |
| Height of deck/roadway | 36.27 m. at towers. |
| Materials | Tower: Granite Deck: Steel truss with a deck grid of high-strength lightweight pre-cast and cured concrete Cables:Steel wire. Some suspenders are steel wire and some solid rods. Stays are wire rope. |
| Maintenance and repair | In the early 1950s modifications were made to create two 3 lane highways between the outer and inner cables.
The deck flooring was replaced by a 75 mm. deep concrete filled steel grid. In 1991 the suspenders, cable posts. stays, main cable wrappings were replaced and suspenders adjusted. All of this was done whilst the traffic flowed with only temporary lane closures allowed during non rush hours. In 1999 the deck was replaced by pre-cast steel and concrete panels. |
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| How to read the bridge | Read more about the book metaphor..... |
|---|---|
| Chapter 1 | Suspension system |
| Paragraphs | Towers: Act as 'props' to hold up the cables. Supporting cables and stays: The system that Roebling devised for spinning the four main cables is the basis of the technique still used today. |
| Sentences | Towers: Solid below deck level and open above. Cables: Four cables hang like a washing line whereas the stays radiate from each tower. |
| Words | Towers: Granite blocks Cables: Individual cables made up of galvanised wires laid parallel. Suspenders and stays are wire rope. |
| Letters | Steel: Iron, carbon with other additives such as chromium etc Concrete: Cement, sand, aggregate and water Reinforced concrete: Concrete is strong in compression but weak in tension where it has to be reinforced with steel bars |
| Chapter 2 | Deck |
| Paragraphs |
Stiffening girders: These are trusses with cross bracing at two levels (see slide no. 8 in slideshow).
They are fixed longitudinally at the towers and anchorages so the structure expands and contracts towards the centre
where there is an expansion joint. Cross girders: These are trusses that span between the longitudinal trusses and carry the deck panels (see slide nos. 9-11 in slideshow). Deck panels: The road surface covers these panels which carry the traffic (also see slide nos. 9-11 in slideshow). |
| Sentences |
Stiffening girders:Each girder has cross braced panels at 2.3 m. centres supported
by a suspender and carrying a floor beam at each point (see slides no. 5 and no. 9 in slideshow). Cross girders:Again these are cross braced panels. |
| Words |
Stiffening girders: The individual components of the truss girders along the deck and truss girders across the deck (see slideshow)with cross bracing. Cross girders: The individual components of the truss girders (see slideshow). Deck panels: The individual panels on which the traffic runs are made of high-strength lightweight pre-cast and cured concrete. |
| Letters | Steel: Iron, carbon with other additives such as chromium etc Concrete: Cement, sand, aggregate and water Reinforced concrete: Concrete is strong in compression but weak in tension where it has to be reinforced with steel bars |
| Chapter 3 | Foundations |
| Paragraphs | Bearings: Caissons: These were large boxes with no bottoms, towed into position and sunk. Compressed air was pumped in to keep water out. The men inside dug the mud and bedrock of the river bed. They stopped when they reached solid rock and the caissons were filled with concrete. The caisson on the Brooklyn side is 13.4 m. below water. The caisson on the Manhattan side is 23.8 m. below water. See Chapter 5 of the book for more detail; the story of how John Roebling was injured and died and also how Washingtom Roebling suffered from the bends through working in the caissons. |
| Grammar | Technically the bridge is a way of taking forces from up in the air down to the ground.
So imagine the flow of those forces through the structure.
Think of a truck standing on the brdge and how its weight is transmitted through the bridge to the ground. Read more about suspension bridges here..... |
| References | Seely H et al, "Technical Survey - Brooklyn Bridge after sixty years", Proc ASCE, Vol 172, Jan 1946 Serzan K P. "Rehabilitation of Brookly Bridge", Structural Engineering International, 4/95, 244-246 |
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