Performance-based earthquake engineering (PBEE) has gained prominence in the engineering community as an approach that allows for more transparent choices about desired earthquake performance of engineered structures. This report considers prospects for the adoption of PBEE innovations by the design community and for use of innovations in making decisions about seismic performance more generally. The relevant literature is considered and case studies are presented regarding innovations in seismic isolation, load and resistance factor design (LRFD), and performance-based earthquake engineering.
It is difficult at this point to gauge the speed with which innovations in performance- based earthquake engineering will be adopted and implemented. Although code guidelines addressing performance-based approaches have been developed, rigorous methods and techniques for performance-based earthquake engineering are still largely on the drawing board. New seismic provisions and some engineering practice, especially with respect to the rehabilitation of buildings, have incorporated performance-based concepts. However, many engineers are just learning about performance-based earthquake engineering. And, under current ways of doing business, building owners, insurers, and other stakeholders only rarely explicitly engage in discussions of desired performance levels.
Patterns in other earthquake innovations, reviewed in this report, suggest that it takes at least two decades to move beyond the initial threshold of early
applications and guidelines to widespread adoption of the innovation. If that pattern holds for PBEE, and if one argues that the initial threshold was reached in the mid to late 1990s, it will be at least another 15 years before PBEE gains widespread currency. Even within a 15-to-20-year time frame, adoption and implementation are far from assured.
For PBEE innovations to gain widespread currency, a number of technical and decision- related challenges must be addressed. The challenges that PBEE faces for adoption and implementation are arguably more daunting than those previously confronting seismic isolation or load and resistance factor design. Nonetheless, there are important lessons from the history of each. Key barriers to the adoption and diffusion of innovations in seismic isolation were the perceived high costs of carrying out seismic isolation, uncertain ties about the technology, and a lack of standards or guidelines for the technology against which building officials and others could assess seismic isolation designs. Key barriers to the adoption and diffusion of LRFD were the lack of necessary computational power and computing routines to carry out the necessary calculations, lack of data concerning performance of structures under different loads and their resistance, and reluctance of practicing engineers to adopt the methodology.
The lessons reviewed here suggest that the key barriers and steps to overcoming them for PBEE are (1) overcoming uncertainty about the PBEE methodology and its benefits, (2) addressing concerns about the costs of employing the methodology, (3) addressing the complexity of the methodology, (4) legitimizing the methodology, (5) establishing a comparative advantage, and (6) facilitating early adoption.
At best, these steps will help facilitate adoption of PBEE by the engineering profession and help foster greater capacity for undertaking PBEE. However, these steps will not increase the demand for PBEE or bring about the more fundamental changes in thinking about earthquake risks by building owners, the financial community, or public officials that are necessary for PBEE to reach its fullest capabilities. These broader transformations of thinking require the design community to be at the leading edge of explaining to clients how to think about choices and tradeoffs in seismic design as they become more transparent with the application of performance-based earthquake engineering analyses.
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