Transcript Training
Concrete 99 Sydney May 1999
Arch Structures - Spanning Past Present and Future Doug Jenkins Reinforced Earth Engineering Manager
The Sydney Opera House and Harbour Bridge
Gladesville Bridge
Why Arches?
Arches are efficient in use of materials
Arch behaviour is now well understood
Kouchi Expressway
Relative Crown Displacement; DY 40 20 0 -20 Actual Standard Non-Lin Elastic SS Non Lin SS -40 0 5 10 15 Fill Height; m 20 25
Arches are now economical to construct
Early Arch Bridges
The Landscape Arch, Utah
The Industrial Revolution
Telfords Proposal for London Bridge
Theories of Arch Design
Robert Hooke, 1676:
"The true mathematical and mechanical form of all manner of arches for building, with the true butment necessary to each of them. A problem which no architectonick writer hath ever yet attemted, much less performed” "As hangs the flexible line, so but inverted will stand the rigid arch."
60 40 20 0 -20 -40 -60 -40 -20 0 20 40
0 -20 -40 -60 -40 60 40 20 -20 0 20 40
David Gregory:
"When an arch of any other figure is supported, it is because in its thickness some catenaria is included"
50 Parabolic arch enclosing a catenary 40 30 20 10 0 -40 -20 0 20 40
An old photograph of Pontypridd Bridge
An-Ji Bridge
The Blackfriars Committee
Eight “gentlemen of the most approved knowledge in building geometry and mechanics” – A clergyman – The Astronomer Royal – A Teacher of medicine – A lawyer – Two professors
Samuel Johnson
"If the elliptical arch be equally strong with the semicircular, that is, if an arch, by approaching to a straight line, looses none of its stability, it will follow that all arcuation is useless… But if a straight line will bear no weight, which is evident to the first view, it is plain like wise that an ellipsis will bear very little, and that as an arch is more curved its strength is increased."
“Publicus” (believed to be Robert Mylne himself) "…so that, if I understand it right, all from the haunches of the arch downward becomes a pier or abutment, to support a small part of the arch in the middle as a segment of a circle.
This middle part, if built like other arches would make a lateral pressure against these abutments, but to take that away he has placed cubical stones, which he calls joggles, in the joints of the arch; so that every stone tends to fall perpendicularly by its being carried along with the one above it, and nor shoved aside as in other arches, which is the cause of the lateral pressure."
Funicular Curve Comparison with circular and parabolic
6 4 10 8 2 0 -10 -5
Fill Height Over Crown = 1000.0m
K =0.00
0 5 10
Funicular Circular Parabolic
Funicular Curve Comparison with circular and parabolic
6 4 10 8 2 0 -10 -5
Fill Height Over Crown = 1.0m
K =0.00
0 5 10
Funicular Circular Parabolic
Funicular Curve Comparison with circular and parabolic
6 4 10 8 2 0 -10 -5
Fill Height Over Crown = 1000.0m
K =1.00
0 5 10
Funicular Circular Parabolic
Funicular Curve Comparison with circular and parabolic
6 4 10 8 2 0 -10 -5
Fill Height Over Crown = 1.0m
K =1.00
0 5 10
Funicular Circular Parabolic
Funicular Curve Comparison with circular and parabolic
6 4 10 8 2 0 -10 -5
Fill Height Over Crown = 1000.0m
K =0.50
0 5 10
Funicular Circular Parabolic
Funicular Curve Comparison with circular and parabolic
6 4 10 8 2 0 -10 -5
Fill Height Over Crown = 1.5m
K =0.50
0 5 10
Funicular Circular Parabolic
Moments on Buried Arch Circular and Funicular Curves 200 100 0 -100 -20 -10 0 Distance From Crow n, m Circular - Final Funicular - Final Circular - Max Funicular - Max 10 Circular - Min Funicular - Min 20
The Twentieth Century
A Monier Arch Bridge
Grafton Road Bridge, Auckland
Salginatobel Bridge
Floating Formwork for Plougastel Bridge
Today and the Future
Shin Hamadera Bridge, Japan
Properties of the ideal arch material High compressive strength at comparatively low cost.
The ability to form any desired shape cheaply and accurately.
Erection without elaborate formwork.
Low maintenance and excellent durability, particularly under compression.