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2015 | Buch

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Seismic Ground Response Analysis

verfasst von: Nozomu Yoshida

Verlag: Springer Netherlands

Buchreihe : Geotechnical, Geological and Earthquake Engineering

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

This book presents state-of-the-art information on seismic ground response analysis, and is not only very valuable and useful for practitioners but also for researchers. The topics covered are related to the stages of analysis: 1. Input parameter selection, by reviewing the in-situ and laboratory tests used to determine dynamic soil properties as well as the methods to compile and model the dynamic soil properties from literature;2. Input ground motion; 3. Theoretical background on the equations of motion and methods for solving them; 4. The mechanism of damping and how this is modeled in the equations of motions; 5. Detailed analysis and discussion of results of selected case studies which provide valuable information on the problem of seismic ground response analysis from both a theoretical and practical point of view.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Propagation of Earthquake Waves in the Ground and Fundamentals of Earthquake Motion

Abstract

Fundamental knowledge on the amplification and the attenuation of the earthquake waves, which is necessary to understand the wave propagation in the ground, is introduced in this chapter.

Nozomu Yoshida

Chapter 2. Introduction of Seismic Ground Response Analysis

Abstract

Computer programs for seismic response analysis have been developed mainly in the field of structural analysis. The analysis of ground might be possible by these computer programs. However, they are not used at present. Significant difference exists in the constitutive model or stress–strain relationships. As soil shows nonlinear behavior at very small strains, a simple model such as a bilinear model is not applicable to soil. We need a computer program that is designed for the seismic ground response analysis, especially to consider stress–strain relationships and to take soil particle–water mixture into account.

Nozomu Yoshida

Chapter 3. Input Earthquake Motions

Abstract

As input earthquake motion for the seismic ground response analysis is usually given a priori as an analysis condition, the engineer need not choose them. This book also stands on the same point of view. It may be, however, necessary to know how it is chosen or determined.

Nozomu Yoshida

Chapter 4. Fundamentals of Soil Mechanics

Abstract

Knowledge on fundamental mechanics that are required in the seismic ground response analysis is introduced in this chapter. Practical models will be explained in Chaps. 7 and 8.

Nozomu Yoshida

Chapter 5. In Situ Soil Testing

Abstract

Mechanical properties of the geomaterial frequently change during the sampling and the traveling as will be described in Sect. 6.5. Therefore, it is recommended to obtain the mechanical properties in situ as possible. As shown in Fig. 4.4, however, an in situ test is difficult to obtain the behavior at large strain. The elastic modulus is to be measured in situ at minimum.

Nozomu Yoshida

Chapter 6. Laboratory Test and Assemble of Test Result

Abstract

In situ test as a tool to obtain the elastic modulus was discussed in the previous chapter. In addition to the elastic soil properties, it is necessary to determine the nonlinear characteristics of soil for the seismic response analysis. These characteristics can only be evaluated by the laboratory tests.

Nozomu Yoshida

Chapter 7. Estimation of Mechanical Soil Properties

Abstract

The best way to obtain the mechanical soil properties for seismic ground response analysis is in situ test for the elastic modulus and laboratory test on undisturbed sample for the nonlinear properties. In the engineering practice, however, this is not always possible. The cyclic deformation characteristics test is a costly test in the practice. The frozen sample requires huge cost to retrieve the highly undisturbed sample, and its applicability is limited to clean sand.

Nozomu Yoshida

Chapter 8. Modeling of Mechanical Soil Properties

Abstract

Methods for modeling the mechanical properties are described in this chapter. Many data are required in the detailed seismic ground response analysis. Therefore, engineers need to know their mechanical meaning.

Nozomu Yoshida

Chapter 9. Equation of Motion

Abstract

Governing differential equation to control the vibration of the ground is called a wave equation, an equation of vibration, or an equation of motion. They are essentially equivalent but appearance may be different depending on the way to derive it.

Nozomu Yoshida

Chapter 10. Equation of Motion: Spatial Modeling

Abstract

The equation of motion is a partial differential equation with respect to space and time. Therefore, it is to be solved against both variables. Among them, a method to solve with respect to space is shown in this chapter and that with respect to time is explained in the next chapter.

Nozomu Yoshida

Chapter 11. Solution in Time

Abstract

Solution in space is described in the previous chapter, whereas solution in time is described in this section. There are two methods. One is made in the time domain by solving the step-by-step time integration scheme, and the other is made by converting the time domain into the frequency domain.

Nozomu Yoshida

Chapter 12. Evaluation of Damping

Abstract

The equation of motion is introduced in Chap. 9 as

$$ m\ddot{u}+c\dot{u}+ ku=-m{\ddot{u}}_g, $$

$$ \ddot{u}+2h{\omega}_0\dot{u}+{\omega}_0^2u=-{\ddot{u}}_g $$

The damping term is recognized as the velocity proportional term in general. There is, however, more damping in the practice, which are listed in the following and will be explained in this chapter:

Nozomu Yoshida

Chapter 13. Evaluation of Accuracy and Earthquake Motion Indices

Abstract

It is impossible to simulate the earthquake motion perfectly in the seismic ground response analysis. In other words, seismic ground response analysis includes error because of the reasons in the following:

Nozomu Yoshida

Chapter 14. Simulation of Vertical Arrays

Abstract

Earthquake records both on the ground surface and in the underground are at least to be obtained in the vertical array earthquake observation; several records are sometimes obtained at different depths. Simulation of these data is a good tool to grasp the accuracy of the seismic ground response analysis and is also a good tool to cumulate experience on the seismic ground response analysis. Recently, a number of vertical array observatories increase such as KiK-net (2010) which covers all Japan, although the number of the vertical array stations is limited in the old days. In order to examine the accuracy of the analysis, it is necessary that a strong ground motion record is obtained. In addition, ground conditions such as soil profile, velocity structure, nonlinear property, etc., are also well known. In this sense, KiK-net is not so useful because detailed soil profile and material properties are not known. As far as the author knows, data that can be used to investigate the accuracy of the nonlinear seismic ground response analysis are not sufficient. They are shown in Table 14.1.

Nozomu Yoshida

Chapter 15. Effect of Various Factors from Case Studies

Abstract

Effect of various parameters on the result of the seismic ground response analysis is discussed through case studies.

Nozomu Yoshida

Backmatter

Titel: Seismic Ground Response Analysis
verfasst von: Nozomu Yoshida
Verlag: Springer Netherlands
Electronic ISBN: 978-94-017-9460-2
Print ISBN: 978-94-017-9459-6
DOI: https://doi.org/10.1007/978-94-017-9460-2