Modeling and Simulation of Earthquakes, Soils, Structures and their Interaction

Abstract

This course will provide students with state of the art finite element methods, tools and models for dynamic modeling and simulation of earthquakes, soils, structures and their interaction.

Objective

This course presents the state of the art finite element methods, tools and models for dynamic modeling and simulation of earthquakes, soils, structures and their interaction. Presentation of the theoretical aspects of Earthquake Soil Structure Interaction (ESSI) will be illustrated using models built using the Real-ESSI Simulator software system.

Content

Week I Course objectives, methodology, computer modeling and simulation system Real-ESSI Simulator. Computational Mechanics field of study, kinematics of deformation, strain, stress, linear and nonlinear elasticity, dynamic equilibrium relations, d’Alembert’s principle, forces in dynamic equilibrium, mass, damping, stiffness, external force, nonlinear analysis cycles Week II Dynamic finite element method (FEM) equations, virtual work method in dynamics, nonlinear dynamic equations of motion, consistent and lumped mass, velocity and displacement proportional damping, Rayleigh and Caughey damping, linear and nonlinear material behavior. Week III Incremental, continuum elasto-plasticity, Material Models (perfectly plastic, hardening and softening. Explicit (forward Euler) and Implicit (backward Euler) constitutive integrations Week IV Direct, time marching solution for dynamics of nonlinear, inelastic systems, general Newmark family of methods, sta-bility and accuracy, nonlinear resonance, numerical damping, explicit and implicit algorithms, unconditionally and conditionally stable Newmark and Hilber–Hughes–Taylor α–method, stability and accuracy, examples) Week V Contact modeling: Hard contact, Soft contact. Axial contact stiffness, shear contact stiffness. Contact gap opening and closing. Saturated contacts, effective stress and buoyant forces on foundations. Week VI Inelastic structural models, beams, plates, walls and shells. Week VII Parallel Computing for elastic-plastic computations, static and dynamic domain decompositions methods, Course and fine grained high performance computing. Multiprocessors, multi-core, graphical processing units (GPUs). Week VIII Elastic–plastic FEM modeling, practical recommendations for development and analysis of nonlinear, elastic-plastic finite element models, phased development of general FEM, and ESSI in particular, models. Core Functionality for inelas-tic/nonlinear modeling. Week IX Introduction: Earthquake Soil Structure Interaction (ESSI) Background, problem definition, seismic motions, seismic body and surface wave field, seismic energy propagation, free field motions, beneficial and detrimental effects, balancing input and dissipated energy. Week X Seismic Motions: Free field vs ESSI motions, incoherent motions, Domain Reduction Method, boundary conditions, radiation damping, 3D inclined wave fields vs 1D vertical motions, nonlinear wave propagation simulations, time step size, element size, earthquake modeling. Week XI Free field motions development, 1C motions, deconvolution and convolution, 3C/6C motions, 3D plane wave solution, regional scale geophysical models, Bay Area regional scale model, (guest lecture by a geophysics expert), use of SW4 program for free field motion development. Week XII ESSI and Liquefaction, fully coupled, porous solid – pore fluid systems formulation, discretization, basic system of DOFs, coupling damping forces, specialization to slow (consolidation) and fast phenomena (ESSI, liquefaction), boundary conditions, initial conditions, stability and accuracy of various algorithms. Week XIII Verification and Validation (definition, procedures, code verification, solution verification, validation experiments, model verification (!)) Week XIV ESSI Modeling and Simulation Synthesis: example building structure (boundary conditions, initial conditions, nonlinear contact (gap/slip), nonlinear soil/rock, 1D vs 3D seismic motions development, buoyant forces at foundation level, etc.)

Resources