Engineering Structures 101 Bridges Compiled by Professor Martin Fahey School of Civil and Resource EngineeringThe University of Western Australia
Arch Bridges: Types of Arches
Pont d’Avignon, France, River Rhone, 1188 Frére Benoît (St Bénézet), leader of “Brothers of the Bridge” [revival of the Roman Guild of Bridge Builders Fratres Pontifices (Ponti-fices = bridge-builders) or Frères Pontifes]. Destroyed deliberately by one of the Avignon Popes for defence reasons. Arches made up of three arcs of a circle
Ponte Vecchio (“Old Bridge”), Florence, 1345. Taddeo Gaddi. Only bridge over the River Arno not destroyed by retreating German Army in WW2. A segmental arch bridge (arches are segments of circles).
Pont de la Concorde, Paris, built by Perronet, 1791. Segmental arches (rubble from La Bastille used to construct the piers)
Common Bridge Types Note that in all cases, the main elements can be solid or trusses.
Beam bridge: bridge deck in bendingdeck could be solid beam (eg concrete), or box section (steel or concrete box section), or truss
Britannia Bridge, Menai Straits, Wales, 1850. First railway bridge designed as deep box girder (two side-by-side rectangular tubes each containing a single rail line). The designer (Robert Stephenson) included towers for adding suspension chains if necessary. Main spans 460 t. wrought iron, total span 461 m consisting of two continuous wrought iron tubes side-by-side. Destroyed by fire in 1970 by two boys!
14th Street Bridge over the Potomac River. Continuous riveted steel girders. Note the absence of internal hinges, and the roller supports at the piers
Continuous steel plate girder bridge. This 3-span bridge has a composite section consisting of the steel girder and the concrete roadway on top. (Near Lausanne, Switzerland)
Continuous steel box girder bridge over the Rhine, Bonn, Germany, 1967. Note varying depth of the box sections
Steel box girder bridge in Koblenz, Germany, collapsed during construction due to buckling. Similar collapses occurred at Millford Haven, Wales, 1970 (4 deaths), and the Westgate Freeway Bridge, Melbourne, 1970 (35 deaths), both designed by Freeman Fox .
Concrete box section beam bridges: one of the Florida Keys bridges, USA (above), and the Linn Cove Viaduct, North Carolina, USA (right). (The Windan Bridge over the Swan River on the Graham Farmer Freeway is a concrete box section bridge, but constructed by incremental launching).
Hinge Simply-supported box-section prestressed concrete bridge, BART system, San Francisco.
Bollman Truss Warren Truss (without verticals) One way of strengthening a simple beam is to use a truss. Railway engineers in the US adopted wooden truss methods for bridge construction for the development of the railway system in the US. Pictures show some of the (many) types of trusses that were developed. Fink Truss Pratt or Howe Truss
Fink “through truss”. 1868, Ohio, US. Compression columns are hollow wrought iron tubes
Bollman Truss Bridge, Laurel, Maryland, USA. The existing bridge was built in 1869 along the B&O Main Line , and moved to the current location in 1888.
Crumlin Viaduct, Ebbw Vale, Wales. Designed by Brunel (1806-59), this early railway viaduct is interesting in that it is constructed entirely from pin-connected iron members. Deck support is by Warren truss elements, simply supported.
Lift bridge, Sacramento River Delta.. A Warren truss with verticals is used throughout. Lift span is simply supported. The double spans on each side are determinate due to internal pins. (Near Rio Vista, California)
Trusses are common elements in many types of buildings Steel Pratt truss spanning between columns Merchant Exchange Building. The outside trusses of this building consist of X-braced 50-ft square panels. The clear span between supporting columns is 100 ft, and the end of the building (foreground) has a 50-ft overhang. (Chicago, Illinois)
Circular Arch Bridge: Pons Fabricus (Ponte Fabrico), Rome, Tiber. Built in 62 B.C. by L.Fabricius. Oldest surviving bridge in Rome. Still used by pedestrians. Note the hole through the centre - relieved water pressure in flood conditions
Earliest existing cast iron bridge: Ironbridge, River Severn, England, built by Abraham Darby, 1779.
Ironbridge, River Severn, England, built by Abraham Darby, 1779. Members in compression; connections using dowels etc.
Buildwise Bridge, River Severn, Thomas Telford (1796): cast-iron bridge half the weight of the Ironbridge
Craigellachie Bridge over the River Spey. An historic bridge, being the first such wrought iron truss arch bridge to be built by Telford in 1815.
St Louis Rail Bridge, St Louis USA, Mississippi River. James Eades, 1874. First true steel bridge. Three spans, each 152 m. Foundations were a major technical challenge (see next slide)
Caisson used to construct piers of St Louis Bridge. Deepest point had 23 m water depth and 30 m below riverbed. (50 m, or 5 atmospheres, of water pressure). Men worked in pressurised chamber at pressures up to 240 kPa (2.4 atmospheres). Because of this, there were 91 cases of the bends, 2 crippled for life, 13 deaths. Would have been much worse except they realised slow decompression and short shifts were necessary. 40 m 20 m
Gateway Arch, St Louis, USA. This free-standing arch is 630 ft. high and the world's tallest. Built of triangular section of double-walled stainless steel, the space between the skins being filled with concrete after each section was placed. Shape is almost perfect “inverted catenary”
Base of the Gateway Arch. The size of cross-section of the arch rib can be seen by comparison with the figures on the ground. The section of the arch at the base is an equilateral triangle with 90 ft. sides. The arch is taken 45 ft. into bedrock. (St. Louis, Missouri)
Construction of the Gateway Arch (St. Louis, Missouri). Arch is not stable on its own until complete.
Interior of Carmel Mission. Built in 1793 it is an interesting design in that the walls curve inward towards the top, and the roof consists of a series of inverted catenary arches built of native sandstone quarried from the nearby Santa Lucia Mountains. (Carmel, California)
Garabit Viaduct, River Truyère, St Flour, France. (Viaduc du Garabit). Built by Gustav Eiffel, 1884. Last (and best) of his many wrought iron bridges. Two-hinged arch design became standard for many to follow. Note shape of the arch.
Garabit Viaduct, River Truyère, St Flour, France. (Viaduc du Garabit).Built by Gustav Eiffel, 1884. Last (and best) of his many wrought iron bridges. Two-hinged arch design became standard for many to follow. This photograph taken September 2002.
Garabit Viaduct, Gustav Eiffel, 1884. The bridge has been repainted recently to a colour that matches the original colour selected by Eiffel. (photograph taken 2002)
Garabit Viaduct.The arches are broad at the base (for stability) and are narrow, but deep, at the top.
Construction of the Garabit Viaduct. Hinged arch segments were tied back to the towers using cables until they joined together. Compare with Sydney Harbour Bridge construction (see later)
Eiffel Tower, Champs du Mars, Paris. 1889. Grew from Eiffel’s bridge-building expertise. Was world’s tallest structure for 40 years. 300 m tower built of puddled iron. The “arch” shape at the bottom is purely decorative.
Graceful ironwork arches in the Musée d’Orsey, Paris, which is now the most beautiful museum in Paris (more manageable in short visit than the Louvre), having being converted from a disused railway station.
Pont Alexandre III, Paris, 1896 / 1898 (Widely regarded as the most beautiful of all of the bridges of Paris. This photograph pre-dates the painting of the bridge for the 1989 bi-centenary of the French Revolution - much gold leaf added then)