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
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The Bridge Today
10
The Bridge Today cont…
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