ABSTRACT
Society relies on its engineers to design structures that are safe and perform as intended. The public
wants to cross bridges, enter buildings, and live downstream of dams without having to give conscious
thought as to whether there is any danger of collapse. The nation’s civil engineers have a distinguished
history of performing this service. As research has progressed, experience has developed and been
codified, and computers have increased computational speed and ability, design methods have become
increasingly sophisticated. Traditional design approaches that rely on allowable stress and factor of safety
36.1 Introduction ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-1
36.2 Safety and Risk Assessment .. . . .. . . . . . . . . . . . . . . . . . . . . . . . . . 36-4
36.3 Failure Cost .. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-7
36.4 Condition Assessment and System Performance .... 36-9 Series Systems Parallel Systems General Systems
36.5 Damage and Deterioration ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-13
36.6 Time-Dependent Reliability .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-16
36.7 Inspection ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-19 Nondestructive Evaluation Inspection Visual Inspection — Condition Ratings Inspection Optimization Updating
36.8 Maintenance and Repair ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-28 Preventive Maintenance Repairs Expected Life Cycle Maintenance Cost
36.9 Discount Rate .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-34
36.10 Condition and Reliability Indices as Joint Performance Indicators .. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-35
36.11 Life Cycle Cost Examples.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-38
36.12 Conclusions .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-45
Acknowledgments .. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-45
Glossary... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-45
Notation ... . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-47
References .. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-48
analysis have expanded to incorporate reliability and system-based performance methods. Design
optimization methods are beginning to examine the entire life cycle performance of a structure. While
this is a new and evolving (and therefore incomplete) field, this chapter explains many of the principles,
concepts, and issues involved in examining the performance of a structure over its entire useful life.
