In this study, the oscillation behavior and the aseismicity of bridge piers with isolating foundations are investigated. An isolating foundation is formed by installing isolation materials such as sand, gravel and PTFE (Teflon sheet) between the footing and the pier foundation and mainly utilizes the relative displacements (sliding and rocking) between the footing and the foundation to absorb and dissipate energy during large-scale earthquakes. The governing equations of motion are derived and dynamic response analyses and model vibration tests on a single pier are carried out. The results show that this isolating system has a significant positive effect in decreasing responses during earthquakes.

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In recent years, high damping rubber (HDR) bridge bearings have become widely used because of the excellent ability to provide high damping as well as flexibility. However, there are few systematic studies on the deterioration problems of HDRs during their service life, and usually the long-term performance was not considered in the design stage. In this research, through accelerated thermal oxidation tests on HDR blocks, the property variations inside the HDR bridge bearing are examined. A deterioration prediction model is developed to estimate the property profiles. Then using a constitutive model and carrying out FEM analysis, the behavior of a HDR bridge bearing during its lifespan is clarified. A design procedure is proposed that takes the long-term performance in the site environment into consideration.

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The positive bending momen tcapacity of composite steel girders is examined through parametric study employing elasto-plastic finite displacement analyses. The effects of initial bending moment on the bending moment capacity and on the web slenderness limit for section classification are investigated. Observations made during the numerical study indicate that the noncompact web slenderness limits in conventional design standards, which are based on tests of steel I-sections, are conservative for composite sections. Many sections, which are classified as slender by current specifications, demonstrate suffficient flexural capacity as noncompact. The conventional web slenderness limits for noncompact sections, independent of initial bending moment seems inappropriate for composite I-girders. The initial bending moment has considerable effect on the noncompact web slenderness limits. The web slenderness limits for compact and noncompact sections are proposed on the basis of the parametric study.

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In this paper, a methodology to estimate the Markovian transition probability model is presented to forecast the deterioration process of bridge components. The deterioration states of the bridge components are categorized into several ranks, and their deterioration processes are characterized by hazard models. The Markovian transition probabilities between the deterioration states which are defined for the fixed intervals between the inspection points in time, are described by the exponential hazard models. The applicability of the estimation methodology presented in this paper is investigated by the empirical data set of steel bridges in New York city.

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The pre-stressed concrete girders with corrugated steel webs (PCGCSW) are known for their numer-ous advantages, including the accordion effect, a high shear strength etc. However, the mechanical analy-sis of these structures has always been a challenge for engineers, since the classical Euler-Bernouilli and Timoshenko theories do not account for the bending behavior and the stress distribution of the PCGCSW. A new theory, called the G3 theory was developed by Machimdamrong et al.(2004) and was found in good accordance with the FEM analysis. In this paper, we propose an extension of the G3 theory by tak-ing into account the inelastic properties of the steel web. FEM analysis is used as a benchmark and gives results very close to the prediction of the elasto-plastic G3 theory.

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This paper presents a new mesh re-generation technique for free surface flow analysis based on the interface-tracking method. The incompressible Navier-Stokes equation based on the arbitrary Lagrangian-Eulerian description is used as the governing equation. The SUPG/PSPG formulation is employed for the finite element discretization. The coupled non-linear finite elemente quation systems are linearlized by the Newton-Raphson method. As numerical examples, the present method is applied to the sloshing problem, the broken-dam problem and the fountain flow problem in a rectangular tank. The efficiency of the present method is shown by these numerical results.

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The authors have been investigating an inverse problem of determining the position and the shape of unknown cracks in a material using velocity waveform data of the ultrasound measured with a laser interferometer. In our previous works, however, only the vertical velocities have been utilized in the crack determination, despite the fact that the horizontal and vertical velocities on the surface of the material are calculated numerically using time domain elastodynamic BIEM in 3D. We measure the particle velocities from the direction tilted from the normal direction to obtain both the horizontal and vertical velocities using the vector decomposition rules for these velocities. We can determine the unknown cracks more accurately using the horizontal and vertical velocity waveforms than using only the vertical velocity waveforms.

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This paper proposes a mathematical model based on a linear time-shift invariant (LTI) system for nondestructive ultrasonic testing (UT). We consider here an entire model of the immersion UT including ultrasonic wave generation in water, transmission from water to solid and vice versa, and scattering by flaws in the solid. A multi-Gaussian beam model is introduced to express wave propagation in both transmission and reception processes. The scattering process is calculated by means of boundary element method. These processes are expressed by frequency dependent modules in the LTI system, and the total output signal is obtained as a product of the modules. The performance of this model is shown by numerical simulations of flaw-echoes from internal and surface-breaking cracks.

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To support local government officials who are in charge of enforcing earthquake disaster mitigation, this paperproposes application of an integrated earthquake simulator to the seismic response analysis of whole structures located in a city. The simulator is aimed at combining various simulation programs which are used for the purpose of design, and visualizing structure responses for a given earthquake scenario. Integration takes advantage of a computer agent which plays a role of an interpreter between the system and each simulation program. The possibility of such integration is discussedby developing a prototype of the integrated earthquake simulator.

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Seepage failure including flowage deformation and hydraulic fracture, plays an important role on damage of dyke under flood, flow of ground caused by liquefaction and improvement of ground by injection and/or penetration procedures. These problems must be solved with interaction among three phases: solid (soil), liquid (water) and gas (air). Discrete analysis (e.g. DEM) is adapted to abruption, failure and flowage, but unsuitable procedure to analysis domain of large scale. Continuum analysis has opposite properties to that.
In this paper, there is a new attempt to develop the procedure which fuses discrete and continuum analyses by ‘Smoothing Particle Hydrodynamics (SPH)’ with account for the interaction among three phases.

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The purpose of this research is to propose a numerical method for the problem of the identification of the elastic coefficients in linear elastic wave field : Determine unknown Young’s modulus and Poisson’s ratio from the knowledge of the plural sets of simultaneous displacement and traction on the surface of an isotropic, linearly elastic bounded body. The elastic body is supposed to be a state of the plane strain. We assume that the density is known in the elastic body. In this research, the Lamé coefficients are identified instead of determining unknown Young’s modulus and Poisson’s ratio. To determine the unknown Lamé coefficients numerically, we adopt the adjoint numerical method. The minimizing problem with some constrains is introduced by using variational method. To find the minimum, a technique based on the projected gradient method is proposed. By numerical experiment, we discuss about the efficacy of our algorithm.

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