1. Milford Haven Bridge Disaster Group 9 Dave Riordan Ciaran Daly Brian Dennehy Martin Faure

2. 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

3. Milford Haven Bridge

4. 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

5. 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

6. Why it collapsed (cont) This section slid forward down the cantilever killing 4 men.

7. Findings Inquiry into the Design and Erection of Steel Box Girder Bridges Concluded that BS153 was inadequate New British Standard, BS5400

8. 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.