The Bridge Collapse at Milford Haven Group 9.ppt
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Transcript The Bridge Collapse at Milford Haven Group 9.ppt
The Bridge Collapse at Milford
Haven
Group 9
David Forde Niall Byrne
Peter Reilly
Ross McDowell
1
Where is Milford Haven?
South West Wales
Cleddau River
Road Traffic
2
Freeman, Fox & Partners
Pioneered the use of the box-girder
principle in most of its bridge
building projects .
Design technology had been in use
for over 30 years
Engineers under pressure to make
structures lighter and therefore
cheaper
3
Freeman, Fox & Partners cont..
2 bridges collapsed during
construction during 1970.
The 1st at Milford Haven killed 4
people
The collapse of the 2nd in Melbourne
killed 35 people
4
The Bridge Design
Built on The BoxGirder Principle
One of the longest
of its type in
construction
(850m)
Erected by
cantilevering
5
The Bridge Design: Cantilevering
Frame above the pier suffers extra loading
due to the cantilevering part
6
The Collapse
Collapse occurred when
the last section of the
second span was being
moved out along the
cantilever
Failure was initiated by
buckling of the support
diaphragm
7
The Collapse cont….
As the diaphragm buckled the
distance between the flanges
decreased
This increased the force required by
the flanges to carry the moment
Load at failure was 9.7kN
Design Load was 5kN
BS153 inadequate
8
Lessons Learned
Merrison Committee, IDWR
Committee’s 27 Recommendations
New British Standard BS5400
9
The Bridge Today
10
The Bridge Today cont…
11