Transcript Milford Haven Bridge Collapse.ppt

Milford Haven Bridge
Collapse
Cathal Kennedy
Terence Meade
Sara Farivarz
Padraig O’Rourke
Contents
Introduction
 Milford Haven
Bridge
 The Collapse
 Results
 Conclusion

Introduction
Box Girders:
used for large 2nd
moment of area &
torsional resistance
 Hard to analyse,
however
 One of 4 similar
bridges that failed
from 1969 - 1971

Milford Haven Bridge
 Box
Girder design
 Consisted of 7 separate spans from
77m to 312m in length
 Built by being cantilevered out from
piers
 Sections then welded or bolted to
end
The Collapse
Occurred when
launching deck
section across
 Stresses during
construction are
very different and
often larger than
when the bridge is
completed

Continued




occurred during
launching a preassembled deck
section towards the
second pier.
subjected to bending
moments and vertical
shear forces.
buckling of diaphragm
lead to buckling of
lower flange.
Load before failure
9700kN
Results
 Committee
of Inquiry concluded that
BS153 was inadequate
 Merrison committee sets rules which
become the basis for BS5400
 West Gate Bridge strengthened but
collapsed 2 months after killing 32.
Conclusion
Ultimately caused
by human error –
failure to anticipate
effects during
construction
 Highlights need for
engineers to fully
understand
principles behind
construction
