Seismic Stability from Low Ductility to Enhanced Resilience

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AbstractThe fundamental basis for seismic stability is clear – during an earthquake, a building must be capable of carrying gravity loads while developing large inelastic deformations and associated lateral displacements. However, structural design to achieve this performance objective is complex and depends upon multiple system parameters. In current seismic provisions, the global destabilizing effects of gravity are typically considered with simplistic models that may not properly address the actual inelastic stability response of building structures. Building systems with high ductility are used extensively in high‐seismic regions, but in moderate‐seismic regions, systems with low ductility are ubiquitous. The inelastic responses of low‐ductility and high‐ductility systems are starkly different, and life safety must be ensured across this wide variation in behavior. This paper will discuss foundational seismic stability principles and explore the range of inelastic response that is associated with conventional seismic systems and novel next‐generation systems. Results from large‐scale component tests, full‐scale frame tests and numerical earthquake simulations will be used to demonstrate several important concepts: (1) high‐ductility response is an insufficient, and not always necessary, condition for seismic stability; (2) the most critical parameter for seismic stability is persistent secondary stiffness; (3) emerging technologies like recentering, which limit damage, are promising solutions for enhanced seismic resilience.