Geoscience Reference
In-Depth Information
Table 13.3. Acceptable level ofdamage in performance-based design
∗
Acceptable level of
damage
Structural
Operational
Degree I:Serviceable
Minoror no damage
Little or no loss of service-
ability
Controlled damage
∗∗
Degree II:Repairable
Short-term lossof
serviceability
∗∗∗
DegreeIII:Nearcollapse
Extensive damage in
nearcollapse
Long-term or complete loss
of serviceability
Degree IV: Collapse
∗∗∗∗
Complete loss of service-
ability
∗
Considerations:Protectionofhumanlifeandproperty,functionsasanemergency basefortrans-
portation, and protection from spilling hazardous materials, if applicable, should be considered in
defining the damage criteria inaddition tothose showninthis table.
∗∗
With limited inelasticresponseand/or residual deformation.
∗∗∗
Structure out of service forshortto moderate time forrepairs.
∗∗∗∗
Without significant effects on surroundings.
Complete loss of struc-
ture
Table 13.4. Performance grades S, A, Band C
Performance grade
Designearthquake
Level 1 (L1)
Level 2 (L2)
Grade S
Degree I: Serviceable
Degree I: Serviceable
Grade A
Degree I: Serviceable
Degree II:Repairable
Grade B
Degree I: Serviceable
Degree III:Near collapse
Grade C
Degree II:Repairable
Degree IV: Collapse
The acceptable level of damage is specified according to the specific needs of the
users/owners of the facilities and may be defined on the basis of the acceptable level
ofstructuralandoperationaldamagegiveninTable13.3.Thestructuraldamagecategory
inthistableisdirectlyrelatedtotheamountofworkneededtorestorethefullfunctional
capacity of the structure and is often referred to as direct loss due to earthquakes. The
operational damage category is related to the amount of work needed to restore full or
partialserviceability.Economiclossesassociatedwiththelossofserviceabilityareoften
referredtoas indirect losses.
Once the design earthquake levels and acceptable damage levels have been properly
defined, the required performance of a structure may be specified by the appropriate
performance grade S, A, B or C defined in Table 13.4. In performance-based design,
a structureisdesigned to meet these performance grades.
