The main aim of this study is to produce deterministic seismic scenarios using an advanced approach based on three-dimensional physics-based numerical simulations (3DPBNS) to characterize strong ground motion from source-to-site in the large urban area of Santiago de Chile due to the seismic hazard of the San Ramón Fault. The 3DPBNS were performed using the open-source software SPEED based on the Discontinuous Garlekin Spectral Element method (Mazzieri, et al., 2013) Because of the limited frequency range of this approach, numerical simulations have to be post-processed with a novel approach based on artificial neural networks (ANN2BB, after Paolucci et al (2018)) to enrich the response in a frequency range for engineering purposes (0 to 25Hz). Numerical scenarios are presented for different magnitudes (from Mw6.0 to Mw7.0) and cyclic soil response (linear visco-elastic and non-linear visco-elastic behavior of shear modulus and damping ratio), in form of peak ground velocity maps (PGV), peak ground acceleration maps (PGA) and pseudo-acceleration maps for several response periods. This results are compared with classical GMPE method to highlight its main features, such as better near-source response characterization, full spatial correlation and physical seismic source features as directivity and radiation patterns. Main results demonstrate the strong ability of 3DPBNS+ANN2BB to describe spatial variability of earthquake ground motion due to topographical, site and seismic source effects for different magnitudes and a wide range of frequencies, as reasonable peak-distance attenuation agreements between this method and GMPE, noticing in peak maps a much better description capacity of near-source effects for 3DPBNS and spatial correlation. For non-linear visco-elastic soil behavior, very limited differences with respect to the linear-elastic case are observed, due to the stiff coarse gravel predominant in the Santiago basin. A discussion of the current Chilean regulation for structural seismic design is proposed, making a simple comparison between scenario-based response spectrum and design spectrum from the regulations on selected sites, showing that a single scenario can significantly surpass the elastic design spectrum of the regulation for all range of periods in some cases.
L'obiettivo principale di questo studio è produrre scenari sismici deterministici utilizzando un approccio avanzato basato su simulazioni numeriche tridimensionali basati sulla fisica (3DPBNS) per caratterizzare forte movimento terra da sorgente-sito della grande area urbana di Santiago del Cile dovuta al rischio sismico della Faglia di San Ramón. I 3DPBNS sono stati eseguiti utilizzando il software open-source SPEED basato sul metodo Discontinuous Garlekin Spectral Element (Mazzieri, et al., 2013) A causa della gamma di frequenza limitata di approccio esta, simulazioni numeriche hanno da essere post-elaborati con un nuovo approccio basato su reti neurali artificiale (ANN2BB, dopo Paolucci et al (2018)) per arricchire la risposta in un intervallo di frequenza per scopi ingegneristici ( Da 0 a 25 Hz). scenari numerici sono presentati per le diverse grandezze (da Mw6.0 a Mw7.0) e risposta del terreno ciclico (lineare viscoelastico e comportamento viscoelastico non lineare del modulo di taglio e rapporto di smorzamento), in forma di mappe di velocità di picco al suolo (PGV), mappe di accelerazione di picco del terreno (PGA) e mappe di pseudo-accelerazione per diversi periodi di risposta. Questi risultati sono confrontati con il metodo GMPE classico per evidenziare le sue caratteristiche principali, come la migliore caratterizzazione della risposta near-source, la piena correlazione spaziale e le caratteristiche della sorgente sismica fisica come i modelli di direttività e radiazione. principali risultati Dimostrare la forte capacità di 3DPBNS + ANN2BB per descrivere variabilità spaziale del terremoto movimento terra a causa topografica, sito ed effetti sorgente sismica per diverse grandezze e una vasta gamma di frequenze, gli accordi attenuazione ragionevole picco-distanza tra metodo esta e GMPE, notando nelle mappe di picco una capacità di descrizione molto migliore degli effetti near-source per 3DPBNS e correlazione spaziale. Per il comportamento visco-elastico non lineare, si osservano differenze molto limitate rispetto al caso lineare-elastico, a causa della rigida ghiaia grossolana predominante nel bacino di Santiago. Una discussione della corrente di regolazione cilena per la progettazione sismica strutturale viene proposto, rendendo semplice confronto tra lo spettro di risposta basata sullo scenario e spettro di progetto dai regolamenti relativi siti selezionati, che mostra che un singolo scenario può superare significativamente lo spettro disegno elastico del regolamento per tutta la gamma di periodi in alcuni casi.
3D physics-based numerical scenarios for earthquake strong ground motion prediction : the case of the San Ramon fault in Santiago de Chile basin
CORTES CAMUS, MATIAS IGNACIO
2017/2018
Abstract
The main aim of this study is to produce deterministic seismic scenarios using an advanced approach based on three-dimensional physics-based numerical simulations (3DPBNS) to characterize strong ground motion from source-to-site in the large urban area of Santiago de Chile due to the seismic hazard of the San Ramón Fault. The 3DPBNS were performed using the open-source software SPEED based on the Discontinuous Garlekin Spectral Element method (Mazzieri, et al., 2013) Because of the limited frequency range of this approach, numerical simulations have to be post-processed with a novel approach based on artificial neural networks (ANN2BB, after Paolucci et al (2018)) to enrich the response in a frequency range for engineering purposes (0 to 25Hz). Numerical scenarios are presented for different magnitudes (from Mw6.0 to Mw7.0) and cyclic soil response (linear visco-elastic and non-linear visco-elastic behavior of shear modulus and damping ratio), in form of peak ground velocity maps (PGV), peak ground acceleration maps (PGA) and pseudo-acceleration maps for several response periods. This results are compared with classical GMPE method to highlight its main features, such as better near-source response characterization, full spatial correlation and physical seismic source features as directivity and radiation patterns. Main results demonstrate the strong ability of 3DPBNS+ANN2BB to describe spatial variability of earthquake ground motion due to topographical, site and seismic source effects for different magnitudes and a wide range of frequencies, as reasonable peak-distance attenuation agreements between this method and GMPE, noticing in peak maps a much better description capacity of near-source effects for 3DPBNS and spatial correlation. For non-linear visco-elastic soil behavior, very limited differences with respect to the linear-elastic case are observed, due to the stiff coarse gravel predominant in the Santiago basin. A discussion of the current Chilean regulation for structural seismic design is proposed, making a simple comparison between scenario-based response spectrum and design spectrum from the regulations on selected sites, showing that a single scenario can significantly surpass the elastic design spectrum of the regulation for all range of periods in some cases.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/145614