Structural health and capacity

In cities, the relationship between exposure and losses is expressed through the physical vulnerability, i.e. a function characterizing the capacity of urban assets to resits and/or dissipate seismic loadings : this is also known as physical resilience, or a capacity whose limit is failure. During their lifetime, the capacity of structures follows the seismic cycle (inter-, co-, post-seismic), and its assessment at every moment is a key scientific and operational issue.

The resulting damage and losses depend on the amplitude of ground motion (IM : intensity measurement) and the response of the structure (EDP : engineering demand parameter), which in the underlying probabilistic framework PBEE (Performance Based-Earthquake Engineering) introduce significant uncertainty. Recordings of earthquakes in structures highlight the internal processes activated, whether linear or non-linear, and provide information on the residual seismic damage that may be expected or observed.

The data, recorded continuously over time, also provide information on the structural condition of buildings (Seismic Structural Health Monitoring S2HM). Continuous monitoring coupled with enhanced signal processing methods and/or AI-based methods, can help for the early detection of damage, the understanding of the co-seismic response of the structure and of the slow recovery (slow dynamics) of structural conditions. In a context of elastic nonlinearity, the rate of recovery provides information on the damage and therefore the residual capacity of the structure at each time in its service life.

References

• Guyer, R. A., & Johnson, P. A. (1999). Nonlinear mesoscopic elasticity : Evidence for a new class of materials. Physics today, 52(4), 30-36.
• Astorga, A., Guéguen, P., & Kashima, T. (2018). Nonlinear elasticity observed in buildings during a long sequence of earthquakes. Bulletin of the Seismological Society of America, 108(3A), 1185-1198.

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