Performance Evaluation Level

No

^^^Verification^^^ c of Final

Design

Quality Assurance During Construction z

Building Maintenance and Function

Figure 2.1 SEAOC Vision 2000 methodology for performance-based seismic design (After OES, 1995)

Table 2.1 SEAOC Vision 2000 recommended performance objectives (After OES, 1995)

Earthquake Performance Level

* Indicates the earthquake return period.

Basic = Basic Objective Essential = Essential/Hazardous Objective Critical = Safety Critical Objective Unacceptable = Unacceptable Performance

Table 2.2 SEAOC Vision 2000 general damage descriptions for new building designs (After OES, 1995)

System /

Building Performance Levels

Elements

Fully Operational

Operational

Life Safety

Near Collapse

Collapse

Overall Building Damage

Negligible

Light

Moderate

Severe

Complete 1

Permissible Transient Drift

<0.2%

< 0.5%

<1.5%

<2.5%

>2.5%

Permissible Permanent Drift

Negligible

Negligible

<0.5%

<2.5%

>2.5%

Vertical Load-Carrying Element Damage

Negligible

Negligible

Light to Moderate, but substantial capacity remains to carry gravity loads

Moderate to heavy, but elements continue to support gravity loads

Partial to total loss of 1 gravity load support 1

Lateral

Load-Carrying Element Damage

Negligible. Generally Mastic response; no significant loss of strength or stiflhess

Light. Nearly elastic response; original strength and stiffness substantially retained; minor cracking/yielding of structural elements; repair implemented at convenience

Moderate. Reduced residual strength and stiffness, but lateral system remains functional

Negligible residual strength and stiffness; no story collapse mechanisms, but large permanent drifts; secondary structural elements may completely fail

Partial or total collapse; primary elements may require demolition

Damage to

Architectural

Systems

L ■ ■■ . —

Negligible damage to cladding, glazing, partitions, ceilings, finishes, etc.; isolated elements may require repair at users ■convenience

Light to moderate damage to architectural systems; essential and select protected items undamaged; hazardous materials contained

Moderate to severe damage to architectural systems, but large falling hazards not created; major spills of hazardous materials contained

Severe damage to architectural systems; some elements may dislodge and fall

Highly dangerous falling hazards; destruction of components 1

Table 2.3 Description of SEAOC Vision 2000 Performance-Based Seismic Design steps (After OES, 1995)

| Step |

Description |

Selection of

Performance

Objectives

A performance objective Is the combination of an expected performance level with an expected level of earthquake ground motion. The selection is made by the client based on consideration of the client's expectation's, the seismic hazard exposure, economic analysis, and acceptable risk. Selecting the performince objectives sets the acceptance criteria for design.

Ertabtah S«e SuNaMityand Deaign Ground

MOUOnS

A site autabWy analysis Includes consideration of the site aelamidty, soil type, and potential site hazards, and detenrination of the sol profile and topography Identification of seismic source« and mechanisms, and tdentitieation of Hquifacbon potential, tsunami exposure, and other hazards. The design ground motions should be determined from a seismic hazard analysis that considers a» critical seismic sources. The form In which the ground motions are characterized (e.g. time histories, acceleration response spectra, or daplacement response spectra) stolid be suitable for the analysis and design methods.

Conceptuel Deelgn

The conceptual deaign of a buldng establishes the overall layout, configuration, selection of structural systems and materials, selection of foundation systems, and selection of non-structural systems. The portions of the structural system that wW be expected to yield and dMpete the earthquake input energy should be Identified.

Prelminary Design

During the preMmjnary design phase, structural framing elements are sized and checked against the design criteria. As a minimum, the deaign should be checked for operational performance and for life safety or ooNapse prevention perfornanoe. Elements of the structural system that wHI be expected to dissipate energy during an earthquake should be proportioned to provide the Intended inelastic performance.

Final Deaign

During the final design phaee, the structural system Is detailed to meet all of the selected performance objectives. Particular attention should be focused on the detsls of those elements that must provide ducttity to ensure acceptable inelastic performs nee. Non-structural elements are designed end detaled to accommodate the etssbc and inelesHc deformations of the structure.

Deaign \MflcaBon

Folowing each design step, a de^gn verification analysis Is performed to verify that the design satisfies the selected performance objective* Depending on the performance objectives snd building configuration, either elastic or Inelastic analysis methods are used to caiculata the structural respones to the design earthquake ground motions. Calculated structural reaponss quantities are oompsred to NmMing values aaaodatad wth the aaleded performance objectives.

Deaign Riviiw

The design review may include both independent peer review snd plsn review by the buHdkig ofAdal. For spedslzed, irregular, or important structures Independent peer review should be required to asaees the design, assumptions, modeling, analyals, and effect^sness of the design in meeting the eeleded performsnos objectfcres. For simpler buildings, the building official wll provide the only independent review of the design

Quality

Assurance During Construction

Quality assurance during construction Involves the design professions!, peer reviewer, building official, spedel inspectors, testing agencies, and the contractor. The quality assurance process ensures that the design Intent is property Interpreted and that the critical elements sre recognized, properly constructed, inspected, and tested In accordance wrtth the applicable building codes.

BufkNng

iwnBfiinov and Function

During the life of the structure, the bulding owner and buldng official must ensure that the earthquake resisting system is not sltered during future remodels or renovations. The owner must maintain the structure to prevent corrosion snd deterioration of the buMdng elements snd to ensure that changes In occupancy and building taction do not adversely affect the behavior of the bulding.

Table 2.4 ATC-40 performance objectives (After ATC, 1996)

"o

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