Uncertainty and Correlation for Loss Assessment of Spatially Distributed Systems

2007 ◽  
Vol 23 (4) ◽  
pp. 753-770 ◽  
Author(s):  
Renee Lee ◽  
Anne S. Kiremidjian
Keyword(s):  
Risk Assessment ◽  
Ground Motion ◽  
San Francisco ◽  
Structural Damage ◽  
Transportation Networks ◽  
Correlation Model ◽  
Loss Assessment ◽  
Monetary Loss ◽  
Coefficients Of Variation ◽  
Spatially Distributed

Seismic risk assessment for a spatially distributed system, such as a lifeline network, involves characterization of ground shaking and structural damage for multiple structures in a region. The expected value of monetary loss, a common measure of the risk, has been previously formulated but with little attention to the uncertainty around this monetary loss. Furthermore, prior research on risk assessment for lifeline systems, in particular transportation networks, assumes no spatial ground motion correlation and no structure-to-structure damage correlation between sites in the network. In this paper, a framework for treating these correlations in the network risk analysis is presented. A demonstration of this methodology is carried out for two transportation networks located in the San Francisco Bay region. Coefficients of variation for network physical loss using a non–distance dependent ground motion correlation model in the framework range between 0.6 and 1.5 for the sample networks presented here. Coefficients of variation for network physical loss using a distance-dependent ground motion correlation model in the framework range between 1.0 and 1.4 for the same networks. It is demonstrated through these applications that assuming no correlation in ground motion and in damage may potentially underestimate uncertainty in the overall loss estimation.

Incorporating Simulated Ground Motion in Seismic Risk Assessment: Application to the Lower Indian Himalayas

2015 ◽  
Vol 31 (1) ◽  
pp. 71-95 ◽  
Author(s):  
Mathilde B. Sørensen ◽  
Dominik H. Lang
Keyword(s):  
Risk Assessment ◽  
Ground Motion ◽  
Near Field ◽  
Earthquake Hazard ◽  
Prediction Equation ◽  
Test Bed ◽  
Loss Assessment ◽  
Ground Motion Simulations ◽  
Finite Fault ◽  
Indian Himalayas

In this study, the effects of implementing stochastic finite fault ground motion simulations in earthquake hazard and risk assessment are evaluated. The investigations are conducted for the city of Dehradun (Indian Himalayas). We compare two ground motion estimation techniques: a ground motion prediction equation–based technique and a simulation-based technique. The comparison focuses on the differences the techniques imply on earthquake damage and loss estimates. Ground motion simulations are first calibrated against the instrumental recordings of the 1991 Mw 6.8 Uttarkashi earthquake. Afterward, a number of events are considered with different magnitude, distance, and azimuth to the source. Results indicate large differences between ground motion and loss estimates derived by the two methods, especially in the direction of rupture propagation, which persist to 2–2.5 fault lengths distance. It is therefore strongly recommended to consider rupture kinematics and orientation to the test bed when providing ground motion estimates for near-field earthquake loss assessment studies.

scholarly journals Toward functional recovery performance in the seismic design of modern tall buildings

2021 ◽  
pp. 875529302110336
Author(s):  
Carlos Molina Hutt ◽  
Anne M Hulsey ◽  
Preetish Kakoty ◽  
Greg G Deierlein ◽  
Alireza Eksir Monfared ◽  
...  
Keyword(s):  
Ground Motion ◽  
San Francisco ◽  
Seismic Design ◽  
Structural Damage ◽  
Tall Buildings ◽  
Residential Building ◽  
Design Guidelines ◽  
Life Safety ◽  
Recovery Times ◽  
The Impact

Current building code requirements for seismic design are primarily intended to minimize life-safety risks due to structural damage under extreme earthquakes. While tall buildings designed under current standards are expected to achieve the life-safety goal, this study estimates that they may require up to 7.5 months of repair to return to functionality after a design-level earthquake (roughly equivalent to ground motion shaking with a 10% probability of exceedance in 50 years), and over 1 year after a risk-targeted maximum considered earthquake (roughly equivalent to ground motion shaking with a 2%–4% chance of exceedance in 50 years). These long downtimes, which correspond to median predictions, far exceed recovery goals for major employers and other recovery-critical uses and can have disproportionately harmful effects on businesses and residents. To address such extensive downtime risks, we evaluate the impact of recovery-based design guidelines for reducing recovery times through (1) more stringent drift limits under expected ground motions and (2) measures to mitigate externalities that impede recovery. The results suggest that by combining these strategies, expected recovery times following a design-level earthquake can be reduced to roughly 1 month, and to 2 months following a risk-targeted maximum considered earthquake. These findings are illustrated for an archetype 42-story reinforced concrete shear wall residential building and a 40-story steel buckling-restrained braced frame office building in San Francisco, CA.

Spatial Correlation Model of Systematic Site and Path Effects for Ground‐Motion Fields in Northern Italy

2019 ◽  
Vol 109 (4) ◽  
pp. 1419-1434 ◽  
Author(s):  
Sara Sgobba ◽  
Giovanni Lanzano ◽  
Francesca Pacor ◽  
Rodolfo Puglia ◽  
Maria D'Amico ◽  
...  
Keyword(s):  
Spatial Correlation ◽  
Ground Motion ◽  
Sedimentary Cover ◽  
Geometric Mean ◽  
Northern Italy ◽  
Correlation Model ◽  
Loss Assessment ◽  
Period Range ◽  
Spatially Correlated ◽  
Systematic Effects

Abstract In this study, we propose an approach to generate spatially correlated seismic ground‐motion fields for loss assessment and risk analysis. Differently from the majority of spatial correlation models, usually calibrated on within‐earthquake residuals, we use the sum of the source‐, site‐, and path‐systematic effects (namely corrective terms) of the ground‐motion model (GMM), obtained relaxing the ergodic assumption. In this way, we build a scenario‐related spatial correlation model of the corrective terms by which adjusting the median predictions of ground motion and the associated variability. We show a case study focused on the Po Plain area in northern Italy, presenting a series of peculiar features (i.e., availability of a dense dataset of seismic records with uniform soil classification and very large plain with variable thickness of the sedimentary cover) that make its study particularly suitable for the purpose of developing and validating the proposed approach. The study exploits the repeatable corrective terms, estimated by Lanzano et al. (2017) in northern Italy, using a local GMM (Lanzano et al., 2016), which predicts the geometric mean of horizontal response spectral accelerations in the 0.01–4 s period range. Our results show that the implementation of a spatially correlated model of the systematic terms provides reliable shaking fields at various periods and spatial patterns compliant with the deepest geomorphology of the area, which is an aspect not accounted by the GMM model. The possibility to define a priori fields of systematic effects depending on local characteristics could be usefully adopted either to simulate future ground‐motion scenarios or to reconstruct past events.

On the characteristics of local geology and their influence on ground motions generated by the Loma Prieta earthquake in the San Francisco Bay region, California

1992 ◽  
Vol 82 (2) ◽  
pp. 603-641 ◽  
Author(s):  
Roger D. Borcherdt ◽  
Gary Glassmoyer
Keyword(s):  
Ground Motion ◽  
San Francisco ◽  
San Francisco Bay ◽  
Ground Motions ◽  
Loma Prieta Earthquake ◽  
Franciscan Complex ◽  
Horizontal Acceleration ◽  
Geological Conditions ◽  
Peak Horizontal Acceleration ◽  
Loma Prieta

Abstract Strong ground motions recorded at 34 sites in the San Francisco Bay region from the Loma Prieta earthquake show marked variations in characteristics dependent on crustal structure and local geological conditions. Peak horizontal acceleration and velocity inferred for sites underlain by “rock” generally occur on the transverse component of motion. They are consistently greater with lower attenuation rates than the corresponding mean value predicted by empirical curves based on previous strong-motion data. Theoretical amplitude distributions and synthetic seismograms calculated for 10-layer models suggest that “bedrock” motions were elevated due in part to the wide-angle reflection of S energy from the base of a relatively thin (25 km) continental crust in the region. Characteristics of geologic and geotechnical units as currently mapped for the San Francisco Bay region show that average ratios of peak horizontal acceleration, velocity and displacement increase with decreasing mean shear-wave velocity. Ratios of peak acceleration for sites on “soil” (alluvium, fill/Bay mud) are statistically larger than those for sites on “hard rock” (sandstone, shale, Franciscan Complex). Spectral ratios establish the existence of predominant site periods with peak amplifications near 15 for potentially damaging levels of ground motion at some sites underlain by alluvium and fill/bay mud. Average spectral amplifications inferred for vertical and the mean horizontal motion are, respectively, (1,1) for sites on the Franciscan Complex (KJf), (1.4, 1.5) for sites on Mesozoic and Tertiary rocks (TMzs), (2.1, 2.0) for sites on the Santa Clara Formation (QTs), (2.3, 2.9) for sites on alluvium (Qal), and (2.1, 4.0) for sites on fill/Bay mud (Qaf/Qhbm). These mean values are not statistically different at the 5% significance level from those inferred from previous low-strain data. Analyses suggest that soil amplification and reflected crustal shear energy were major contributors to levels of ground motion sufficient to cause damage to vulnerable structures at distances near 100 km in the cities of San Francisco and Oakland.

Conditioned Simulation of Ground-Motion Time Series at Uninstrumented Sites Using Gaussian Process Regression

2021 ◽  
Author(s):  
Aidin Tamhidi ◽  
Nicolas Kuehn ◽  
S. Farid Ghahari ◽  
Arthur J. Rodgers ◽  
Monica D. Kohler ◽  
...  
Keyword(s):  
Time Series ◽  
Gaussian Process ◽  
Ground Motion ◽  
San Francisco ◽  
Earthquake Engineering ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Free Field ◽  
Gaussian Process Regression ◽  
Motion Time

ABSTRACT Ground-motion time series are essential input data in seismic analysis and performance assessment of the built environment. Because instruments to record free-field ground motions are generally sparse, methods are needed to estimate motions at locations with no available ground-motion recording instrumentation. In this study, given a set of observed motions, ground-motion time series at target sites are constructed using a Gaussian process regression (GPR) approach, which treats the real and imaginary parts of the Fourier spectrum as random Gaussian variables. Model training, verification, and applicability studies are carried out using the physics-based simulated ground motions of the 1906 Mw 7.9 San Francisco earthquake and Mw 7.0 Hayward fault scenario earthquake in northern California. The method’s performance is further evaluated using the 2019 Mw 7.1 Ridgecrest earthquake ground motions recorded by the Community Seismic Network stations located in southern California. These evaluations indicate that the trained GPR model is able to adequately estimate the ground-motion time series for frequency ranges that are pertinent for most earthquake engineering applications. The trained GPR model exhibits proper performance in predicting the long-period content of the ground motions as well as directivity pulses.

Building Seismic Vulnerability Study for China High Rises

2013 ◽  
Vol 353-356 ◽  
pp. 2301-2304
Author(s):  
Fan Wu ◽  
Ming Wang ◽  
Xin Yuan Yang
Keyword(s):  
Ground Motion ◽  
Structural Damage ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Response Spectrum ◽  
Earthquake Ground Motion ◽  
Published Data ◽  
Rapid Urbanization ◽  
High Rise ◽  
Story Drift

High-rise buildings, as a result of rapid urbanization in China, become one of popular structure kind. However, there have been few seismic vulnerability studies on high-rise buildings, and few fragility curves have been developed for the buildings. Based on the published data of more than 50 high rises and super high rises, the structural information such as building heights, mode periods, locations and sites, the maximum design story drift ratios, are collected and analyzed. The vulnerability analysis for high rises uses response spectrum displacement as seismic ground motion input, since the structures have comparatively long natural period. Using statistics and regression analysis, the relationship between the maximum story drift ratio and response spectrum displacement is established. Based on height groups and earthquake design codes, the fragility curves of different performance levels can be developed. These curves can provide good loss estimation of high rise structural damage under earthquake ground motion.

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