Geotechnical Engineering Award Winner: 181 Fremont, San Francisco

Kirk Ellison
Senior Engineer
Arup, San Francisco

Site-Specific Seismic Hazard and Ground Motion Use for Performance-Based Design of Tall Buildings

The emerging performance-based seismic design methodology aims to achieve more reliable seismic designs by specifying and attaining performance objectives gauged in terms of structural response under various earthquake hazard levels. The reliability of the seismic performance evaluation of structures substantially depends on the accuracy of the nonlinear models of the structures and the characteristics of the ground motions used for nonlinear response history analysis (NRHA).

Ideally, ground motions that accurately represent earthquake hazards that are likely to strike the buildings in their lifetime should be used in NRHA. Current seismic design provisions in ASCE 7-10 and ASCE 7-16 provide seismic hazard maps and methods to construct target response spectrums for design and analysis. However, there is a lack of guidance on the assessment of the seismic hazard and the development of a representative set of ground motions for a specific building site that conform to the performance-based design methodology.

This presentation aims to provide important information on the sensitivity of site-specific seismic hazard analysis and ground motion selection for use in the evolving performance-based design and assessment of tall buildings. It will examine the state-of-practice in seismic hazard analysis, ground motion selection and application for the performance based seismic design of new structures and the assessment of existing structures. It will also provide an understanding of the United States Geological Survey (USGS) seismic hazard map and the seismic hazard used in the ASCE 7 seismic design provisions. Finally, two site-specific seismic hazard analysis examples will be provided for sample building sites in Los Angeles and San Francisco.

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