The collapse of the bridge is a tragic event and can lead to loss of life and serious property damage. That is why bridge engineers, designers and builders always have to take their work very seriously. The best way for them to prevent these accidents is to understand why the bridge collapses. Understanding the collapse of the bridge can lead to significant changes in the design, construction and safety of future architectural projects.
In bridge projects, the main focus of the designer is to provide the appropriate load-bearing capacity based on the assumed load and the strength of the material used, and this process is very important.
However, it is rare that errors in calculations are the main reason for the collapse – small errors are offset by safety factors, both the live load and the strength of the material. In addition, there is also extra inbuilt safety in static systems where the assumptions usually made are on the safety side (as an exception to this conclusion, we could mention the failure of the Quebec bridge– see Chapter 4 –it was partly due to errors in calculations and the fact that the safety factor was more or less omitted).
Instead, when bridge failures are being studied, the main causes are much more cleaning (i.e., when fast-flowing water spoils the foundation of the piers and abutments) and/or loading on the bridge.
However, even though scouring and damming are responsible for most (about 50%) of bridge failures, the actual case in this book does not exactly match this cause (still the failure of the Peace River bridge is approaching– see Chapter 8). Instead, I have come to focus on the causes of failures that designers usually need to control more (earthquake damage has also been ruled out for the same reason). The causes of the presented failures areas follows:
Insufficient strength of the materials used, lack of inspection and maintenance, traffic, fatigue and brittle fracture, buckling, wind loading, air instability, fire, collision damage from insufficient anchorage capacity.
Finally, in1977, I was invited by two British scientists, P.G.Sibly and A.C.Take the opportunity to comment on a very interesting hypothesis presented by Walker.