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Proceedings of the International Conference on 57
Advances and New Challenges in Earthquake
Engineering Research, Hong Kong Volume
A FRAMEWORK FOR DEVELOPING PERFORMANCE-
BASED EARTHQUAKE ENGINEERING
Jack P. Moehle
Pacific Earthquake Engineering Research Center
University of California, Berkeley
ABSTRACT
Performance-Based Earthquake Engineering seeks to improve seismic risk decision-making
through assessment and design methods that have a stronger scientific basis and that express
options in terms that enable stakeholders to make informed decisions. A key feature is the
definition of performance metrics that are relevant to decision making for seismic risk
mitigation. In concept, these metrics consist of estimates of losses due to earthquakes,
including direct losses (repair and restoration costs), loss in functionality (or downtime), and
casualties.
The first generation of performance-based earthquake engineering assessment procedures in
the United States provides approximate relationships between structural response indices
(interstory drifts, inelastic member deformations and member forces) and performanceoriented
descriptions such as Immediate Occupancy, Life Safety and Collapse Prevention.
However, the relationship between the structural indices and performance measures are very
approximate, determined in part by calibration to expectations of performance intended by
current building code provisions, and in part by engineering judgment of various experts.
Moreover, specific expectations of the performance targets are not clearly defined.
Efforts under way by researchers in Pacific Earthquake Engineering Research (PEER) center
aim to develop a more robust methodology for performance-based earthquake engineering -
one that breaks the process into logical elements that can be studied and resolved in a rigorous
and consistent manner. The process begins with definition of a ground motion Intensity
Measure, which defines in a probabilistic sense the salient features of the ground motion
hazard that affect structural response. The next step is to determine Engineering Demand
Parameters, which describe structural response in terms of deformations, accelerations, or
other response quantities calculated by simulation of the building to the input ground motions.
Engineering Demand Parameters are next related to Damage Measures, which describe the
condition of the structure and its components. Finally, given a detailed probabilistic
description of damage, the process culminates with calculations of Decision Variables, which
translate the damage into quantities that enter into risk management decisions. Underlying
the entire methodology is a consistent framework for representing the inherent uncertainties in
earthquake performance assessment.
While full realization of the methodology in professional practice is still years away,
important advances are being made through research in the Pacific Earthquake Engineering
Research Center. The discussion will describe the overall approach and some specific
highlights.