Transcript Disaster_Pres.ppt

Pontypridd Arch Bridge Collapse
Introduction
Pontypridd located on confluence of River Taff
and Rhondda.
Pont-y-ty-pridd, the Welsh for "bridge of earth“.
1746 - William Edwards was commissioned to
build a bridge in Pontypridd for £500.
Included in his commission was a guarantee
clause that he had to maintain it for a minimum
of 7 years.
William Edwards (Feb 1719 – Aug 1789)
Born at Ty Canol, Groeswen
Also built bridges in Aberafan, Betws and Usk. His most
famous project was the Old Bridge at Pontyridd.
The first 3 Old Bridge attempts failed due to torrential
waters in Taff and being too heavy.
4th when constructed was largest single span in the world
at the time, measuring 140ft.
Solution was to make the bridge lighter by leaving
cylindrical voids.
Completed bridge opened in 1755.
250 yr anniversary in 2005, and its still standing as a
monument to Edwards’ efforts
Another bridge beside it carries traffic.
Was the Worlds longest single span bridge for 40 yrs.
1st Attempt – Three arch stone bridge
Lasted 26 months
Failure – Bridge was swept away in a flood
due to loading on the supports
2nd Attempt – Single span bridge
Failure
 Due to weak formwork?
 Due to another storm?
Result –bridge collapsed during
construction
3rd Attempt – Single span bridge
Failure – Loading on haunches was to great
Result – slow collapse over a period of 6
weeks. Edwards was able to observe and
learn from this collapse
4th Attempt – single span bridge with some
added features
Features
 Use of charcoal as fill-material
 Cylindrical voids
Result – Success
Conclusion
Lack of Design Codes
Challenging environment (floods)
Trial and error
Final Bridge – regarded as an Engineering
failure
Useful information on Arch construction for
Future designers