Transcript milford haven bridge disaster.ppt

Milford Haven Bridge Disaster
Group 9
Dave Riordan
Ciaran Daly
Brian Dennehy
Martin Faure
Introduction
• Box Girder Designs look simple
• However, difficulties arise in calculating
the stresses
• During construction box girders often act
as cantilevers
• Can be subjected to large bending
moments at the piers
Milford Haven Bridge
Milford Haven Bridge
• Box Girder Design
• Consisted of 7 different spans between
77m and 213m in length
• These sections were cantilevered out from
the piers
• When ends met, sections welded or bolted
together
Why it Collapsed
• It occurred when the last section of box for
the second span was being moved out
along the cantilever
• Bending moments and vertical shear
forces led to buckling of diaphragm which
in turn lead to buckling of lower flange
Why it collapsed (cont)
• This section slid forward down the
cantilever killing 4 men.
Findings
• Inquiry into the Design and Erection of
Steel Box Girder Bridges
• Concluded that BS153 was inadequate
• New British Standard, BS5400
Conclusion
• This disaster occurred because of the
failure to anticipate effects during
construction
• Led to changes in contractual procedures
and in checking designs and construction
procedures.