Eads Bridge

Webpage developed by David Aynardi

Contents

Introduction Background Design & Construction Modifications Spandrel Bracing Length of Spans Storm Damage Collisions Pneumatic Piling West Abutment Floating Cofferdam Theory Numerical Results References Contact Form
Appendix
1  Woodward Ch XXVI
Other Projects
Introduction Background Design & Construction Modifications Spandrel Bracing Length of Spans Storm Damage Collisions Pneumatic Piling West Abutment Floating Cofferdam Theory Numerical Results References Contact Form
Appendix 1  Woodward Ch XXVI
Other Projects

Introduction

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Eads_Bridge_panorama.jpg
Eads Bridge
Wikimedia Commons photo

Eads Bridge

Eads Bridge is a combined road and railway bridge connecting the cities of St. Louis, Missouri and East St. Louis, Illinois. Opened in 1874, it was the first bridge across the Mississippi south of the Missouri River. It is the oldest bridge on the river.

Eads Bridge is named for its designer, James Bucannon Eads (1820 – 1887). Eads was a St. Louis industrialist and inventor with interests in marine salvage, steamboat-building, and related industries. He also had investments in a variety of St. Louis enterprises including banks, streetcar lines, real-estate, and regional railroads.[1]

Significance of the Bridge

Longest Bridges

When a bridge at St. Louis first began to receive serious consideration, the longest rigid spans in existence were the 460 foot box-beams of Robert Stephenson's 1850 "Britannia Bridge", in Wales, UK.

In 1868, while work was in progress on Eads Bridge, the 505 foot truss at the Kuilenburg (Culemborg) railway bridge was completed in Holland. Kuilenburg was a wrought-iron truss and included some Bessemer steel components.

The 520 foot center arch of Eads Bridge held the “longest span” title until 1877 when it was surpassed by Gustave Eiffel's “Maria Pia” railroad bridge in Porto, Portugal. The Maria Pia Bridge features a two-hinge arch with a 525 foot span. It is entirely wrought-iron.

The size and unruly nature of the Mississippi inspired ground-breaking technical solutions.

When the bridge opened, the 520 foot center arch was the longest rigid clear-span ever constructed (only a few suspension bridges were longer).

Extending more than 100 feet below water level, the bridge's foundations were the deepest underwater structures of their time. The foundations were installed using pneumatic caissons, a pioneering use of this technology in the United States and, when they were built, by far the largest caissons anywhere.

The primary load-carrying members of the arches are steel. This was the first large-scale application of steel as a structural material, and initiated the shift from wrought- and cast-iron to steel as the default material for major structures.

The arches, with their rigidly-connected ends, are statically indeterminate. This yielded structural efficiency, but required numeric analysis of a sophistication rarely attempted before to the advent of electronic computers.

Histories of the Bridge

Caissons

In construction, the term “caisson” can mean an enclosure with an open top and bottom, used to retain the sides of a pit during excavation or it can refer to a pneumatic caisson, a pressurized enclosure with an open bottom, used to enable construction personnel to work below water.

In the 1868 “Report of the Chief Engineer,” Eads used the term in the first sense. Later, after changing the design to use pneumatic caissons, he used it in the second. To clarify, I added the qualifier “open” when describing the 1868 scheme.

Eads Bridge is the subject of one of the canonical works on the history of American engineering; C.M. Woodward's superb A History of the St. Louis Bridge, published in 1881. Writing just a few years after the bridge was completed, Woodward was acquainted with many of the individuals who took part in the bridge's design and construction and could draw on their personal reminiscences, journals, and correspondence. Woodward also had access to the construction drawings, many of which he arranged to have copied to create the wood-cuts and engravings that illustrate the book.

With the subject so exhaustively covered, later writers are largely consigned to re-working the trove of information provided by Woodward. Three publications that provide new perspectives are Robert W. Jackson's Rails Across the Mississippi (2001), Quinta Scott and Howard S. Miller The Eads Bridge (1979), and John Kouwenhoven's 1982 article, The Designing of the Eads Bridge.

This Website

These pages are a concise narrative of the construction and later modification of the bridge. I've drawn on the above-mentioned publications and other sources, especially concerning events in the later career of the bridge. Where it is helpful, I've added detail about the industrial resources that were available to the bridge's builders. I've tried to shed some light on the apparent paradox, that the "first steel bridge" was built in a country that effectively lacked a steel industry.

The Author

David Aynardi is an architect, originally from St. Louis. Eads Bridge has been a lifelong interest, inspired originally by family visits to the St. Louis riverfront and more recently by David's own experience working on large construction projects, which instilled respect for difficulties surmounted by Eads and his staff.


Copyright © 2019-, David Aynardi
Footnotes
  1. Jackson, p17.^

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