Design criterion and
methodologies have been developed and implemented that require bridges to be
without significant damage following severe ground shaking. The design
philosophy used to obtain these results is often referred to as “Performance
Based Design.” These criteria differ from traditional codes in that they
correlate levels of damage noted in laboratory testing and real earthquake
damage to quantifiable material properties and design parameters. This design
approach provides reliability of a structure’s performance by addressing the
requirements of a defined load path and using rational analytical methods to
envelope the expected demands on the structure. The result is a reasonable
level of confidence in achieving the desired structural behavior and predefined
performance.