Deaggregation of Probabilistic Ground Motions for Selected Jordanian Cities

Probabilistic Seismic Hazard Analysis (PSHA) approach was adopted to investigate seismic hazard distribution across Jordan. Potential sources of seismic activities in the region were identified, and their earthquake recurrence relationships were developed from instrumental and historical data. Maps of peak ground acceleration and spectral accelerations (T=0.2 and T=1.0 sec.) of 2% and 10% probability of exceedance in 50 years were developed. This study deaggregated the PSHA results of 2% and 10% probability of exceedance in 50 years results of twelve Jordanian cities to help understand the relative control of these sources in terms of distances and magnitudes. Results indicated that seismic hazard across these cities is mainly controlled by area sources located along the Dead Sea Transform (DST) fault system. Cities located at short distances from the DST tend to show close deaggregation behavior. Some discrepancies may exist due to the proximity or remoteness of these cities relative to the DST seismic sources and local seismicity. The modal or most probable distance distribution indicated that the distance to the earthquake which contributes most to the hazard at each city is mainly controlled by shaking along faults associated with near seismic area sources. The influence of adjacent seismic sources to the seismic hazard of each city is more evident for the long period spectral acceleration. Distant sources, such as the eastern Mediterranean, Cyprus, Suez and the southern region of the Gulf of Aqaba are relatively low, but can not be neglected due to the intrinsic uncertainties and incomplete seismic data

ALE and Fluid Structure Interaction for Sloshing Analysis

Liquid containment tanks are, generally, subjected to large deformationsunder severe earthquake conditions due to coupling forces between tankand the contained liquid. The accurate description of these forces is vital inorder to diminish or eliminate the potential risk of tank failure during anearthquake. Yet, analytical formulations derived for the seismic analysis ofliquid storage tanks are not capable to capture the complex fluid-structureeffects since they include many assumptions and simplifications not onlyfor the behavior of fluid and structure but also for the external excitation. Onthe other hand, an appropriate numerical method allows us to cope withlarge displacements of free surface of the fluid, high deformations of thestructure and correctly predicts the hydrodynamic forces due to thehigh-speed impacts of sloshing liquid on a tank wall and roof. For thispurpose, a new coupling algorithm based on the penalty formulation offinite element method which computes the coupling forces at the fluidstructureinterface is developed in this paper. This algorithm is constructedon a two superimposed mesh systems which are a fixed or moving ALEmesh for fluid and a deformable Lagrangian mesh for structure. The fluid isrepresented by Navier-Stokes equations and coupled system is solvedusing an explicit time integration scheme. In order to verify the analysiscapability of coupling algorithm for tank problems, numerical method isapplied for the analyses of a rigid rectangular tank under harmonicexcitation and a flexible cylindrical tank subjected to earthquake motionand numerical results are compared with existing analytical andexperimental results. Strong correlation between reference solution andnumerical results is obtained in terms of sloshing wave height

Physics-Based Hazard Assessment for Critical Structures Near Large Earthquake Sources

We argue that for critical structures near large earthquake sources: (1) the ergodic assumption, recent history, and simplified descriptions of the hazard are not appropriate to rely on for earthquake ground motion prediction and can lead to a mis-estimation of the hazard and risk to structures; (2) a physics-based approach can address these issues; (3) a physics-based source model must be provided to generate realistic phasing effects from finite rupture and model near-source ground motion correctly; (4) wave propagations and site response should be site specific; (5) a much wider search of possible sources of ground motion can be achieved computationally with a physics-based approach; (6) unless one utilizes a physics-based approach, the hazard and risk to structures has unknown uncertainties; (7) uncertainties can be reduced with a physics-based approach, but not with an ergodic approach; (8) computational power and computer codes have advanced to the point that risk to structures can be calculated directly from source and site-specific ground motions. Spanning the variability of potential ground motion in a predictive situation is especially difficult for near-source areas, but that is the distance at which the hazard is the greatest. The basis of a “physical-based” approach is ground-motion syntheses derived from physics and an understanding of the earthquake process. This is an overview paper and results from previous studies are used to make the case for these conclusions. Our premise is that 50 years of strong motion records is insufficient to capture all possible ranges of site and propagation path conditions, rupture processes, and spatial geometric relationships between source and site. Predicting future earthquake scenarios is necessary; models that have little or no physical basis but have been tested and adjusted to fit available observations can only “predict” what happened in the past, which should be considered description as opposed to prediction. We have developed a methodology for synthesizing physics-based broadband ground motion that incorporates the effects of realistic earthquake rupture along specific faults and the actual geology between the source and site

Physics-Based Hazard Assessment for Critical Structures Near Large Earthquake Sources

We argue that for critical structures near large earthquake sources: (1) the ergodic assumption, recent history, and simplified descriptions of the hazard are not appropriate to rely on for earthquake ground motion prediction and can lead to a mis-estimation of the hazard and risk to structures; (2) a physics-based approach can address these issues; (3) a physics-based source model must be provided to generate realistic phasing effects from finite rupture and model near-source ground motion correctly; (4) wave propagations and site response should be site specific; (5) a much wider search of possible sources of ground motion can be achieved computationally with a physics-based approach; (6) unless one utilizes a physics-based approach, the hazard and risk to structures has unknown uncertainties; (7) uncertainties can be reduced with a physics-based approach, but not with an ergodic approach; (8) computational power and computer codes have advanced to the point that risk to structures can be calculated directly from source and site-specific ground motions. Spanning the variability of potential ground motion in a predictive situation is especially difficult for near-source areas, but that is the distance at which the hazard is the greatest. The basis of a “physical-based” approach is ground-motion syntheses derived from physics and an understanding of the earthquake process. This is an overview paper and results from previous studies are used to make the case for these conclusions. Our premise is that 50 years of strong motion records is insufficient to capture all possible ranges of site and propagation path conditions, rupture processes, and spatial geometric relationships between source and site. Predicting future earthquake scenarios is necessary; models that have little or no physical basis but have been tested and adjusted to fit available observations can only “predict” what happened in the past, which should be considered description as opposed to prediction. We have developed a methodology for synthesizing physics-based broadband ground motion that incorporates the effects of realistic earthquake rupture along specific faults and the actual geology between the source and site