Page 100 - Bridge and Highway Structure Rehabilitation and Repair

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Bridge Failure

Studies

and Safety

Engineering

3.1 HISTORY OF DISASTERS AND SAFETY MANAGEMENT
3.1.1 Unexpected Material Deterioration and Failure
Engineering is usually about avoiding failures and investigating why

failures occur and ways to fix the problem. There is a need to understand
the conditions giving rise to past failures and ways to avoid such failures so Administrative Issues
that loss of life can be minimized. Historical events and selected case stud-
ies demonstrate the causes of each type of failure. Future design codes can

make use of the defi ciencies identified in order to develop guidelines for safe
practice. If failures are interpreted correctly, a great deal of information for
correct analysis, anticipated behavior, detailed design, and construction can Section 1
be obtained to help formulate accurate design guidelines.
Failures occur in different forms in a material. Physical forms of failure

can be seen as infinitely large deformation and metallurgical disintegration
of elements. It can be localized cracking without collapse or discontinuity or
total separation in a component.
At failure, critical sections for plastic hinges are located at the midspan
of beams or under the concentrated load where deflection or bending moment

is highest. It can also be at a support where shear force, reaction, or negative
bending moment is the highest.
Failures are encountered on construction sites and are not just confi ned
to the collapse of structures. Deaths and injuries to construction workers
by far exceed the number of fatalities of the bridge users in failure events.
Structural design methods related to construction loads and equipment need
to be refi ned.
Physical causes are varied such as erosion, reversal of stress, impact, vibra-
tions, wind, and extreme events. Usually, it is a combination of dead load stress

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