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Engineering Structures 101 Arch Bridges: Types of Arches Bridges Compiled by Professor Martin Fahey School of Civil and Resource Engineering The University of Western Australia Pons Augustus, Rimini, Italy, AD 14 Typical Roman circular arch bridge Engineering Structures 101: Bridges Pont Neuf (“New Bridge”), Paris, 1578 / 1604 Circular Arch Bridge Page Pont d’Avignon, France, River Rhone, 1188 Frére Bent (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 Pont de la Concorde, Paris, built by Perronet, 1791 Segmental arches (rubble from La Bastille used to construct the piers) Construction of Pont de la Concorde, Paris 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) Engineering Structures 101: Bridges Page Common Bridge Types Note that in all cases, the main elements can be solid or trusses Simple beam bridge: stone slabs on stone supports (Dorset, England) Beam bridge: bridge deck in bending deck could be solid beam (eg concrete), or box section (steel or concrete box section), or truss Engineering Structures 101: Bridges 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! Page 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) Engineering Structures 101: Bridges 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 Page Hinge 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) Simply-supported box-section prestressed concrete bridge, BART system, San Francisco Mt Henry Bridge Widening Bollman Truss Warren Truss (without verticals) Fink Truss Pratt or Howe Truss Engineering Structures 101: Bridges 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 Page Crumlin Viaduct, Ebbw Vale, Wales Designed by Brunel (1806-59), this early railway viaduct is interesting in that it is constructed entirely from pinconnected iron members Deck support is by Warren truss elements, simply supported 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 Engineering Structures 101: Bridges 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) Page Simply-supported steel truss railway bridge, UK 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 50ft 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) Engineering Structures 101: Bridges 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 Page Earliest existing cast iron bridge: Ironbridge, River Severn, England, built by Abraham Darby, 1779 Buildwise Bridge, River Severn, Thomas Telford (1796): cast-iron bridge half the weight of the Ironbridge Ironbridge, River Severn, England, built by Abraham Darby, 1779 Members in compression; connections using dowels etc 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 Engineering Structures 101: Bridges Page 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” 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 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, crippled for life, 13 deaths Would have been much worse except they realised slow decompression and short shifts were necessary 40 m 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) 20 m Engineering Structures 101: Bridges Page Construction of the Gateway Arch (St Louis, Missouri) Arch is not stable on its own until complete 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 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 This photograph taken September 2002 Engineering Structures 101: Bridges Page 10 Brooklyn Bridge, New York George Washington Bridge, New York 1931 Span (1067 m) was 518 m longer than the record at the time Engineering Structures 101: Bridges George Washington Bridge, New York 1931 Towers originally meant to be clad, but people grew to like the look of the lattice structure, and so it was left as is George Washington Bridge, 1067 m span Page 21 Towers are 305 m high, the tallest of their time Golden Gate Bridge, 1937 Main span of 1280 m was the longest single span at that time and for 29 years afterwards Principal designer Joseph Strauss had previously collaborated with Ammann on the George Washington Bridge in New York City Golden Gate Bridge, 1937 Cable “saddle” on top of one of the towers Golden Gate Bridge, 1937 View from the top of one of the towers, showing the main cables and suspender cables Section of the cable, showing it to be made up of a bundle of small cables Forth Road Bridge, over Firth of Forth, Scotland Opened on September 4,1964 Following sequence of slides illustrates some stages of construction Engineering Structures 101: Bridges Page 22 Forth Road Bridge Top of south tower showing the first wires of the cable being laid over the saddle The wires are mm diameter with an ultimate strength of 1500 MPa Each ‘strand’ contains 314 wires , and there are 37 stands in each cable: 11,618 wires and 600 mm diameter Forth Road Bridge Looking up the cable to the south tower saddle Note the bundles or 'strands' of wires that will form the finished cable The individual wires are colour-coded to assist in the spinning operation Forth Road Bridge Cable saddle at the top of the side tower Note the size of the saddle which has to take the resultant vertical component of cable tension due to the angle change in the cable at this location Forth Road Bridge View from the top of the south main tower The so-called 'cable-spinning' operation, originally devised by Roebling, consists of unreeling a continuous length of wire back and forth across the bridge until a 'strand' is built up The wire is looped round the wheel of the traveling sheave (shown) which is connected to an endless hauling rope Engineering Structures 101: Bridges Page 23 Forth Road Bridge After the cable has been laid, the stiffening truss is constructed symmetrically about both main towers This view, taken before the truss has reached the side towers or met at midspan, shows the geometry of the finished cable supporting the unfinished truss Forth Road Bridge Close-up of the unfinished end of the stiffening truss taken from the south side tower The truss has a warren configuration with verticals, and the top and bottom chords are box sections Note the scale of the truss from the figures on the closest vertical member (See old Firth of Forth Bridge in the background) Forth Road Bridge View of the south cable anchorage at the same construction stage as in previous slide Note the scale from the figures to the left of the anchorage Anchor Block for the Rainbow Suspension Bridge, Tokyo Bay, Japan Engineering Structures 101: Bridges Page 24 Replacement bridge Tacoma Narrows http://www.me.utexas.edu/~uer/papers/paper_jk.html Main deck girder is now a very deep open truss, much stiffer in torsion (and bending) that the original, and less susceptible to vortexinduced vibrations Tacoma Narrows Bridge (Washington State, USA) Collapsed on November 7, 1940 Caused by torsional oscillations induced by vortex-shedding Current suspension bridge decks have moved towards aerodynamic shapes that not suffer vortex shedding (eg Humber Bridge, UK, 1981) Severn Bridge 1966 (next slide) was first that used this shape Humber Bridge, UK, 1981 Severn Bridge, UK (1966) Revolutionary aerodynamic shape of the bridge deck avoided the problems of wind-induced vortex shedding that caused the torsional vibrations of the Tacoma Narrows bridge Now the standard shape of suspension bridge decks Engineering Structures 101: Bridges Page 25 Millenium Bridge, London New footbridge across the Thames in London, 2000 Closed due to pedestrian-induced oscillations Akashi-Kaikyo Suspension Bridge, Japan Links city of Kobe with Awaji Island World’s longest bridge (Main Span 1991 m) Progression in increase in bridge spans for past 200 years Engineering Structures 101: Bridges Akashi-Kaikyo Bridge, Japan Links Kobe with Awaji Island World’s longest span (1991 m) Page 26 Akashi Kaikyo Bridge, Japan Overall length 3.9 km Proposed Messina Strait Bridge (Italy-Sicily) Schematics of the cables (left) and towers (right) Note main span: 3.3 km (current longest is 1.99 km)! Proposed Messina Strait Bridge (Italy-Sicily) Longitudinal section (top) and crosssection through the deck (above) All dimensions are in metres Engineering Structures 101: Bridges Page 27 Forth Railway Bridge Completed in 1889, this 4-span cantilever and suspended span bridge was one of the major engineering achievements of its day, and at the time had the world's longest clear spans of 521 m The bridge was built by being cantilevered in a balanced manner about each pier This procedure included the suspended spans which were subsequently released at the hinges Forth Railway Bridge Completed in 1889 Engineering Structures 101: Bridges Forth Railway Bridge A train passing over the bridge emphasises the massive scale of the tubular members Québec Bridge during construction Bridge collapsed during construction (twice!), killing many workers First collapse was due to insufficient bracing of compression members (buckling occurred) Page 28 Carquinez Bridge (Venezuela) central truss lifting (same system used in Québec bridge) Completed Québec Bridge Note extra bracing 2nd accident occurred during lifting the central section (jacks failed) Québec Bridge: The Collapse of September 11, 1916 Jacking system failed when lifting the central span into place Royal Albert Bridge, Saltash This historic bridge, built by I K Brunel in 1859, consists of a combination of wrought iron tube arch ribs and suspension chains Each span is 142 m (Cornwall, England) Engineering Structures 101: Bridges Page 29 Royal Albert Bridge, Saltash, River Tamar, England 1858 I.K Brunel Wrought iron Cable stay bridges: Various arrangements of the cables Royal Albert Bridge, Saltash Raising one of the arches into position Engineering Structures 101: Bridges Page 30 Albert Bridge across the River Thames One of the earliest cable-stayed bridges, it opened in 1873 Main span 117 m (London, England) Albert Bridge across the River Thames One of the earliest cable-stayed bridges, it opened in 1873 Main span 117 m (London, England) Engineering Structures 101: Bridges A notice at the end of the Albert Bridge requests that soldiers 'break step' when crossing, indicating that the possibility of a resonant effect was recognized Dynamic effects can be important in cable structures on account of their potential flexibility and consequent low natural frequencies (see current problems with Millennium Bridge, London) Pont du Normandie (River Seine, Le Harve, France) 856 m main span - longest in the world up to 1999 Longest now is Tatara Bridge, Japan, 890 m) Page 31 Pont du Normandie (River Seine, La Harve, France) Arrangement of the cables Secondary cables are to dampen vibrations of main cables Pont du Normandie (River Seine, La Harve, France) during construction Engineering Structures 101: Bridges Cable-stayed bridge in Germany Note cables only go to centre (between the two roadways) Cable-stayed bridge in Germany during construction - balanced cantilever method Page 32 Modern Bridge Design Many outstanding bridge designers are creating bridges that are both functional and beautiful Many examples in Europe and elsewhere Ganter Bridge (1980) spanning an Alpine valley, near the Simplon Pass in Switzerland Cable stayed bridge (see previous slide) Ganter Bridge (1980), near the Simplon Pass in Switzerland Designed by Christian Menn, this is an interesting example of a cable-stayed bridge, though the cables are inside a thin concrete wall The overall layout of the bridge is Sshaped in plan, the 174 m main span is straight, but the side spans, including the back-stay cables, have 200-m radius curves Ganter Bridge (1980) spanning an Alpine valley, near the Simplon Pass in Switzerland, and shown during construction Designed by Christian Menn, this is an interesting example of a cable-stayed bridge, though the cables are inside a thin concrete wall The overall layout of the bridge is S-shaped in plan, the 174 m main span is straight, but the side spans, including the back-stay cables, have 200-m radius curves The taller pier is 150 m high Engineering Structures 101: Bridges Page 33 Footbridge, La Défense, Paris (1980s) Very elegant steel arch suspension bridge Campo Volantin Footbridge, Bilbao, Spain, 1990 - 1997 Santiago Calatrava Steel inclined parabolic arch with glass decking Alamillo Bridge, River Guadalquivir, Seville, Spain 1987-1992 One of series of extraordinary bridges by Spaniard Santiago Calatrava Length: 250 m Max span: 200 m.Mast height: 142 m The extraordinary weight of the mast (steel filled with concrete) angling back at 58º is enough to support the bridge deck without the need for counter-stay cables This was a first in bridge design, and creates a stunning display Campo Volantin Footbridge, Bilbao, Spain, 1990 - 1997 Santiago Calatrava Steel inclined parabolic arch with glass decking Engineering Structures 101: Bridges Page 34 Model of Lusitania Bridge, Gaudiana River, Médira, Spain 1991 Santaigo Calatrava (engineer and architect!) Sources The pictures contained in this presentation were either downloaded from the Internet, or scanned in from books The main sources used are: • • Engineering Structures 101: Bridges David Bennett: “The Creation of Bridges” Chartwell Books Inc • Lusitania Bridge, Gaudiana River, Médira, Spain 1991 Santaigo Calatrava (engineer and architect!) Godden Slide Library, University of California, Berkeley http://www.eerc.berkeley.edu/godden/index.html “The Builders: Marvels of Engineering” National Geographic Society, Washington D.C • Many other Internet sites, too numerous to mention Page 35