On some recent achievements of earthquake simulation

AbstractThis paper presents some recent achievements of earthquake simulation, which is divided into the seismic wave propagation simulation and the seismic structure response simulation. These achievements are based on rigorous mathematical treatment of continuum mechanics problems, and numerical algorithms of solving the problems are developed. A multi-scale analysis method is developed for the seismic wave propagation simulation; numerical dispersion is reduced by introducing a new discretization scheme. A smart treatment of crack initiation and propagation is developed for the seismic structure response simulation, so that a numerical experiment is made for failure processes by using numerous samples of one structure

Time Critical Mass Evacuation Simulation Combining A Multi- Agent System and High-Performance Computing

This chapter presents an application of multi-agent systems to simulate tsunami-triggered mass evacuations of large urban areas. The main objective is to quantitatively evaluate various strategies to accelerate evacuation in case of a tsunami with a short arrival time, taking most influential factors into account. Considering the large number of lives in fatal danger, instead of widely used simple agents in 1D networks, we use a high-resolution model of environment and complex agents so that wide range of influencing factors can be taken into account. A brief description of the multi-agent system is provided using a mathematical framework as means to easily and unambiguously refer to the main components of the system. The environment of the multi-agent system, which mimics the physical world of evacuees, is modelled as a hybrid of a high-resolution grid and a graph connecting traversable spaces. This hybrid of raster and vector data structures enables modelling large domain in a scalable manner. The agents, which mimic the heterogeneous crowd of evacuees, are composed of different combinations of basic constituent functions for modelling interaction with each other and environment, decision-making, etc. The results of tuning and validating of constituent functions for pedestrian-pedestrian, car-car and car-pedestrian interactions are presented. A scalable high-performance computing (HPC) extension to address the high-computational demand of complex agents and high-resolution model of environment is briefly explained. Finally, demonstrative applications that highlight the need for including sub-meter details in the environment, different modes of evacuation and behavioural differences are presented

Automated Model Construction for Seismic Disaster Assessment of Pipeline Network in Wide Urban Area

This chapter is on rational seismic damage assessment over a wide area through the development of a module for the automated model construction of a pipeline network of lifelines using geographic information system (GIS) data. The module is assigned a functionality that can generate a simple one-dimensional line model and a two-dimensional surface model with high fidelity for the pipe shape. The source code of the module is written in object-oriented programming in order to make it easier to extend it to generate other analysis models. The module was applied to the actual GIS, and the shape of the output model was verified. Numerical analysis was performed on the output of the module, and it showed that the automatically constructed model is mechanically valid and can be used for seismic response analysis

Application of New Inverse Analysis Method to Crust Deformation of Japanese Islands

東京大学Scedule:17-18 March 2003, Vemue: Kanazawa, Japan, Kanazawa Citymonde Hotel, Project Leader : Hayakawa, Kazuichi, Symposium Secretariat: XO kamata, Naoto, Edited by:Kamata, Naoto

Application of continuum forms for predicting elastic wave properties of brick mortar system

We developed three continuum forms for brick structures, predicted the elastic wave characteristics and investigated the range of validity of the predictions. One of the continuum form is based on continuumnization by Hori et al. and the other two are based on Taylor series expansion. Both continuumnization and second order Taylor expansion based continuum forms can predict p- and s-wave characteristics accurately for wavelengths larger than 7 times the brick dimensions. The second order Taylor expansion can also predict the r-wave characteristics accurately in the same range of wavelengths. It is demonstrated that the full Taylor series based continuum form can predict the elastic wave properties to a remarkable accuracy for the whole range of frequencies and wave num- bers. These predictions will be useful in verification of simulation codes, utilizing FEM for analyzing brick structures and engineering applications like non-destructive testing, vibration control, etc

Integrated Earthquake Simulator to Generate Advanced Earthquake Disaster Information

Realistic simulation of possible earthquakes is crucial for producing a rational counter plan against earthquake disasters. This paper presents such a simulation method, the Integrated Earthquake Simulator (IES), which uses a computer-based high-resolution strong ground motion (SGM) simulator and a Virtual Reality (VR) city constructed from GIS/CAD data. The IES is an integrated computer system that is intended to simulate all phases of earthquakes numerically: earthquake hazards, earthquake disasters, and human and social actions against earthquake disasters. An efficient combination of GIS/CAD data and numerical simulation tools for each phenomenon on this computer system can achieve integrated earthquake simulation. This paper presents the methodology of reconstruction of a VR city and the IES prototype. An example of a VR city model is reconstructed and some earthquake disaster simulations are undertaken to examine the IES performance

Tsunami Analysis Method with High-Fidelity Crustal Structure and Geometry Model

Higher fidelity seafloor topography and crustal structure models have become available with accumulation of observation data. Previous studies have shown that the consideration of such high-fidelity models produces significant effects, in some cases, on crustal deformation results that are used as inputs for tsunami analysis. However, it is difficult to apply high-fidelity model of crustal deformation computations to tsunami computations because of large computational costs. In this paper, we propose a new crustal deformation computation method for estimating inputs for tsunami computations, which is based on a finite element analysis method with remarkable reduction of computation costs by efficient use of the arithmetic space and the solution space. This finite element analysis method enables us to conduct 102−3-times crustal deformation computations using high-fidelity models with a degree of freedom on the order of 108 for the 2011 Tohoku earthquake example. Tsunami computations with typical settings are conducted as an application example to present the advantages and characteristics of the proposed method. Comparisons between results of the proposed and the conventional method reveal that large shallow fault slip around the trench axis may lead to significant differences in tsunami waveforms and inundation height distributions in some cases

Development of higher order particle discretization scheme for analysis of failure phenomena

This paper presents the higher order extension of Particle Discretization Scheme (PDS) and its implementation in FEM framework (PDS-FEM) to solve boundary value problems of linear elastic solids, including brittle cracks. Higher order PDS defines an approximation fd(x) of a function f(x), defined over domain Ω, as the union of local polynomial approximation of f(x) over each Voronoi tessellation elements of Ω. The support of the local polynomial bases being confined to the domain of each Voronoi element, fd(x) consists of discontinuities along each Voronoi boundaries. Considering local polynomial approximations over elements of Delaunay tessellation, PDS define bounded derivatives for this discontinuous fd(x). Utilizing the inherent discontinuities in fd(x), PDS-FEM proposes a numerically efficient treatment for modeling cracks. This novel use of local polynomial approximations in FEM is verified with a set of linear elastic problems, including mode-I crack tip stress field