Farzad Naeim, president of Farzad Naeim, Inc., and Ting Lin, assistant professor at Texas Tech University concluded the day by summarizing some of the significant points and to emerge throughout the workshop.
Naeim said that the present marks a unique moment in structural engineering history due to the increasingly complex challenges the field faces and the emergence of novel capabilities, such as the use of robots for inspection and repair. Cyber-physical systems and smart technologies and materials are here, and they will continue to advance. Tremendous and continued technological progression has culminated in highly sophisticated analysis, methodologies, and computing capabilities that were unimaginable 20 years ago. The list of structural engineering’s new features also includes performance-based design, structural health monitoring, fragility-based structure classifications, and ShakeCast-based vulnerability evaluations.
Naeim asserted that there are two dominant challenges the engineering community faces. The first is referred to as “the heritage that will either make us proud or doom us,” or, existing infrastructure. As engineers confront and solve structural and technical problems in the future, centuries-old infrastructure and problems of the past remain. The second challenge is community outreach. “We only talk to ourselves; we need to learn to talk to other people,” Naeim explained. The engineering community needs to educate the public on resilience issues, learn about the public’s needs from the public, earn community trust, affect public policy, and build a coalition of stakeholders.
Lin echoed many of Naeim’s remarks, and also focused on what she believed to be the big needs for engineering. Though the workshop’s diverse assembly of speakers and presenters demonstrated the existence of technological solutions for increased resilience, reaching building owners and officials, stakeholders, and the broader community remains an obstacle to community resilience. She explained that engineers like David Mar are needed to help integrate advanced technologies into structural engineering, and simple and effective tools, like performance-based design, are needed to connect the engineering world with its ultimate users. Further, as research quickly progresses, a way to bring academic research to practicing engineers is needed, and codes and standards must be rethought.
To ensure the delivery of accurate and balanced information to the general community, Lin called for increased transparency between the engineering community and the public. She maintained that the public should be involved in the determination of performance objectives. “We can keep doing our fantastic research in our own group, but we also want to understand what is really needed out there,” she explained.
An audience member asked speakers whether there were any proposed methods to align U.S. structural engineering practices to those of the global engineering community. This was followed by a question of how engineering practices in developing countries could be used to inform those in the United States. Mar responded with a story about a woman he had encountered in Nepal who was serving as her own “general contractor” for construction of her house. She had a prescriptive set of drawings, and had hired and supervised laborers to construct the home. The drawings were from a nongovernmental organization and were drafted for use by lay people. Though the woman did not know anything about engineering, these drawings included the best practices. Mar further recounted during the same trip visiting a professional engineering office and some of its job sites. Though the engineers had college degrees, he alleged that these sites were “really scary.” He reasoned that good results could be reached with a certain set of prescriptive practices, even without an education or degree. “I think sometimes we should look at the problem a little differently,” he concluded.
DesRoches referenced the devastating earthquake in Haiti in 2010, which set a standard for earthquake recovery from financial and human loss. Factors like Haiti’s lack of finances, regulations, and earthquake education demonstrate to the world that earthquake resilience involves more than just resilient buildings. Social and political systems are also involved.
Next, an audience member commented on the recent changes to infrastructure in Los Angeles. Recently tall buildings have been constructed downtown; however, there was a long period without this type of construction. He asked how an area’s seismic conditions affect decisions about tall building design. Naeim responded that the reason for the lack of tall building construction was not technical; it was economic. Thus, the recent construction of tall buildings is the result of an economic boom. Naeim explained that most of Los Angeles’s tall buildings are designed according to performance-based design procedures and must undergo peer review. He further asserted that the engineering community generally agrees that code design does not satisfy implicit performance objectives for tall buildings. For this reason, cities like Seattle have moved to enforce performance-based design. Lin added that the process for decision making in performance-based design could be improved—for example, moving beyond intention-based building codes. Lin recommended the review of earthquake shaking classifications (from rarest to most frequent) and the incorporation of probabilistic thinking into the code.
One audience member voiced his reservations against performance-based design. His view was that performance-based design is essentially based on calculations of displacement and capacity sufficiency at certain points in a structure. He believed these methods were deficient because they did not account for earthquake duration or frequency content. Further, he suggested that the use of response spectrums could be misleading because research has demonstrated that earthquake records with different durations, frequencies, and magnitudes, can yield the same spectrum. Naeim disagreed and explained that performance-based design does not involve the targeting of spectrums or linear or static analysis. Instead, performance-based tall buildings like those in major cities in California undergo dynamic response history analysis. He cited one such building that requires 26 pairs of records for each level of ground motion be evaluated.
The same audience member countered with his belief that an energy-based design method would account for a system’s physics more effectively. In other words, he suggested it would be more efficient to determine a building’s quality by its capacity to absorb or dissipate energy. Further, it was his opinion that future earthquake design methods were likely to be energy-based.
Lin responded that the engineering framework can always be refined to reflect different additional components. She then concluded, “Thanks to high performance computing and advances in earthquake science, I think there is really lots of potential in terms of connecting different elements from science [and] engineering to policy and also enabling advanced technology, which was the theme of today’s workshop.”
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