Izuru Takewaki

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Papers by Izuru Takewaki

Efficient semi-analytical generator of initial stiffness designs for steel frames under seismic loading. Part 2: Slender frame

Structural Design of Tall Buildings, Jun 1, 1997

ABSTRACT

Optimum Design of Elastically Supported Plane frames for Constrained Fundamental Natural Period and Constrained Minimum Stiffnesses

学術講演梗概集. 構造系, Sep 8, 1983

Future directions

CRC Press eBooks, Feb 17, 2021

Performance of Innovative Controlled Buildings Under Resonant and Critical Earthquake Ground Motions

This eBook is the fourth in a series of books on the critical earthquake response of elastic or e... more This eBook is the fourth in a series of books on the critical earthquake response of elastic or elastic-plastic structures under near-fault or long-duration ground motions, and includes six original research papers which were published in the specialty section Earthquake Engineering in ‘Frontiers in Built Environment’. Several extensions of the first eBook, the second eBook and the third eBook are included here. The first article is on the comparison of earthquake resilience of various building structures including innovative base-isolation systems and control systems. Pulse-type ground motions and resonant harmonic ground motions are used for investigating the earthquake resilience of those innovative building structures. The second article is concerned with the performance of an innovative seismic response controlled system with shear walls and concentrated dampers in lower stories. The resonant one-cycle sine waves and resonant harmonic waves are used as the input ground motions. The third article is related to the robustness evaluation of a base-isolation building-connection hybrid controlled building structure under the critical long-period and long-duration ground motion. The multi impulse is used as a substitute for a long-period and long-duration ground motion and the model reduction to a single-degree-of-freedom (SDOF) system is conducted to propose a simple response evaluation method. The fourth article is an extension of the previously proposed energy balance approach to a damped bilinear hysteretic SDOF system under a double impulse as a substitute for a near-fault ground motion. The energy absorption through viscous damping is incorporated appropriately in the energy balance and the application of the proposed method to actual recorded ground motions is presented. The fifth article is on the robustness evaluation of base-isolation building-connection hybrid controlled building structures considering uncertainties in deep ground. The earthquake ground motion amplitude at the earthquake bedrock is evaluated by the Boore’s stochastic method in 1983 including the fault rupture and the wave propagation into the earthquake bedrock. Then the phase angle property at the earthquake bedrock is investigated by introducing the concept of phase difference which is defined for each earthquake type. A wave at the ground surface nearly resonant to the base-isolation building-connection hybrid controlled building structure is produced by considering uncertainties in deep ground. The sixth article is concerned with the critical response of nonlinear base-isolated buildings considering soil-structure interaction under a double impulse as a substitute for a near-fault ground motion. The complicated model of a nonlinear base-isolated building on ground is modeled into an SDOF system after a few model reduction processes. The approach presented in this eBook, together with the previous eBooks, is an epoch-making accomplishment to open the door for simpler and deeper understanding of structural reliability and resilience of built environments in the elastic-plastic and nonlinear range

Seismic Stiffness Design of Pile-Supported Building Structures Using Dynamic Winkler-Type Spring Models

Nihon Kenchiku Gakkai kōzō-kei ronbunshū, 2003

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Inverse optimal damper placement via shear model for elastic–plastic moment-resisting frames under large-amplitude ground motions

Engineering Structures, 2022

Critical Excitation for Earthquake Energy Input in Soil-Structure Interaction System

This chapter discusses the method of critical excitation for earthquake energy input in a soil-st... more This chapter discusses the method of critical excitation for earthquake energy input in a soil-structure interaction (SSI) system. It is true that, while the analysis of SSI effects has been focused on the investigation in terms of deformation and force, not much has been done for the investigation in terms of earthquake input energy to the SSI system. This chapter explains a new evaluation method of earthquake input energy to SSI systems. It is an approach in the frequency domain. Because the inertial interaction and the kinematic interaction are well described by frequency-dependent functions, the present approach based on the frequency-domain analysis is appropriate and effective. Especially, it is demonstrated that even SSI systems including embedded foundations can be treated in a simple way. The effects of the foundation embedment on the earthquake input energies to the super-structure and to the structure-foundation-soil system can be clarified systematically. The works by boundary forces on their corresponding displacements defined for various boundaries are utilized in evaluating the energy flow in SSI systems. The evaluation of earthquake input energy in the time domain is suitable for the evaluation of the time history of input energy.

Critical Excitation for Acceleration Response

Elsevier eBooks, 2013

This chapter discusses a probabilistic critical excitation method for acceleration responses of n... more This chapter discusses a probabilistic critical excitation method for acceleration responses of nonproportionally damped structural systems to nonstationary inputs. Recently, acceleration responses are considered important from the viewpoint of the protection and maintenance of functionality in buildings. Therefore, it is natural and desirable to develop critical excitation methods for acceleration. In contrast to most of the conventional critical excitation methods, a stochastic acceleration response at a point is treated as the objective function to be maximized. The power and the intensity of the excitations are fixed, and the critical excitation is found under these restrictions. The key to finding the new nonstationary random critical excitation for nonproportionally damped structural systems is the order exchange in the double maximization procedure with respect to time and to the power spectral density (PSD) function. Various numerical examples have been incorporated in this chapter. These examples demonstrate the effectiveness and validity of the present critical excitation method. They also reflect that there exist peculiar time-varying characteristics of the generalized nonstationary transfer function multiplied by the envelope function of the input motion model. It is concluded that the damping installation in upper stories is effective in reducing the acceleration.

Role of Records During the 2011 Off the Pacific Coast of Tohoku Earthquake in Seismic Resistant Design of Nuclear Power Station

The 2011 off the Pacific coast of Tohoku earthquake (Mw9.0) had two main wave phases. They are pr... more The 2011 off the Pacific coast of Tohoku earthquake (Mw9.0) had two main wave phases. They are precious records produced by the series of large earthquake. This phenomenon can be interpreted using the concept of the consolidated-type earthquake. The after-shock (Mw7.1) occurred near the Oshika peninsula on April 7th as the intra plate earthquake. We mainly analyzed the seismic records which were measured at the underground of the Onagawa Nuclear Power Station (NPS). The typical displacement pulse wave was identified by the Ricker wavelet. The directivity of the ground movement was detected. This agrees with the direction of permanent movement measured by GPS system. From the displacement profile from O.P.17.0m to O.P.-128.4m, the uniform deformation of underground soil was found and was evaluated from the shear strain in the underground. The non-stationary Fourier spectra indicated that the maximum amplitude of seismic record (O.P.-8.6m; Onagawa NPS) was comparable with that of the code-specified S2 artificial wave and this fact corresponds to the small damage of the Onagawa NPS. Furthermore the seismic records at the Kashiwazaki-Kariwa NPS during the Niigata-ken Chuetsu-oki earthquake and at the Hamaoka NPS during the Suruga-Bay earthquake in 2009 were compared with the code-specified design motion (S2 artificial wave). The validity of the current code for the NPS is discussed

Fundamental Properties of Earthquake Input Energy on Single and Connected Building Structures

Critical Excitation for Earthquake Energy Input Rate

Elsevier eBooks, 2007

Publisher Summary This chapter discusses a critical excitation method for earthquake energy input... more Publisher Summary This chapter discusses a critical excitation method for earthquake energy input rate. It explores a new probabilistic critical excitation method for identifying the critical frequency content of ground motions maximizing the mean earthquake energy input rate to structures. The critical excitation problem includes a double maximization procedure with respect to time and to the power spectral density (PSD) function. The key for finding the critical frequency content is the order interchange in the double maximization procedure. No mathematical programming technique is required in the proposed method. It is shown that the proposed technique is systematic and the critical excitation can be found extremely efficiently within a reasonable accuracy. Extension of the proposed method is discussed to a more general ground motion model. The chapter discusses the process to derive a new expression on the probabilistic earthquake input energy and its rate in terms of uniformly modulated and non-uniformly modulated ground motion models. The process to formulate a new critical excitation problem with the probabilistic earthquake energy input rate as the criticality measure is mentioned.

Critical steady-state response of SDOF bilinear hysteretic system under multi impulse as substitute of long-duration ground motions

Frontiers in Built Environment, Jul 28, 2017

A set of multiple impulses is introduced as a substitute of many-cycle harmonic waves which repre... more A set of multiple impulses is introduced as a substitute of many-cycle harmonic waves which represent the long-duration earthquake ground motion. A closed-form expression is derived of the elastic-plastic response of a single-degree-of-freedom structure with bilinear hysteresis under the "critical multiple impulse input." As in the case of elastic-perfectly plastic models, an advantageous feature can be used such that only the free-vibration exists under the multiple ground motion impulse and the energy balance approach plays a key role in the derivation of the closed-form expression of a complicated elastic-plastic response. It is demonstrated that the critical inelastic maximum deformation and the corresponding critical impulse timing can be obtained depending on the input level. The validity and accuracy of the proposed theory are confirmed through the comparison with the response analysis to the corresponding sine wave as a representative of the long-duration earthquake ground motion.

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Stiffness Design of Irregularly Eccentric 3D-Shear Building Models for Specified Seismic Interstory Drifts

日本建築学会学術講演梗概集B 構造1, 1994

Overview of Seismic Critical Excitation Method

Elsevier eBooks, 2007

Publisher Summary This chapter presents a detailed overview of seismic critical excitation method... more Publisher Summary This chapter presents a detailed overview of seismic critical excitation method. It begins by defining the critical excitation. It is natural to imagine that a ground motion input resonant to the natural frequency of the structure is a critical excitation. The method of critical excitation was proposed by Drenick for linear elastic, viscously damped SDOF systems in order to take into account inherent uncertainties in ground motions. This method is aimed at finding the excitation producing the maximum response from a class of allowable inputs. It was suggested that the critical excitation introduced by Drenick is conservative compared to the recorded ground motions. To resolve this problem, the concept of “subcritical excitation” was introduced. The concept of critical excitation may enable structural designers to make ordinary buildings more seismic resistant. However, critical excitation problems for fully non-stationary excitations and critical excitation problems for elasto-plastic responses under those excitations are challenging problems.

Analysis and design of non-linear seismic isolation systems for building structures—An overview

Frontiers in Built Environment

In this paper, the development of non-linear building isolation systems is overviewed. The study ... more In this paper, the development of non-linear building isolation systems is overviewed. The study summarizes commonly used linear building isolation systems in two categories, which are building base isolation systems and building inter-storey isolation systems. Typical isolators including Lead-Rubber Bearings Friction Pendulum Bearings inter-storey viscous damper and Tuned Mass Damper are reviewed. The analysis and design of linear building isolation systems are also reported. After that, non-linear building isolation systems are introduced from two aspects based on their dynamic characteristics. They are (i) non-linear stiffness isolators including Quasi-Zero Stiffness isolators and Non-linear Energy Sink and (ii) non-linear damping isolators including power-law viscous dampers and magnetorheological dampers. Practical implementations of these non-linear isolators are introduced. Finally, the analysis and design of non-linear building isolation systems are discussed. Traditional eq...

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統計的モデル更新手法に基づく高層建築物の剛性同定【JST・京大機械翻訳】

Analytical Example Using the Extended Rod Theory

Dynamic analysis of skyscrapers can be easily calculated by mean of the extended rod theory propo... more Dynamic analysis of skyscrapers can be easily calculated by mean of the extended rod theory proposed in this book. For the dynamic calculation, you can use the application software “SSDe” explained in Chap. 7. This chapter shows how to calculate the cross section constants of a rod in which a skyscraper is replaced with an equivalent rod. These sectional constants are necessary for input data.

Earthquake Response Analysis of High-Rise Buildings

This chapter presents a summary of dynamic analytical methods for high-rise buildings in Japan. T... more This chapter presents a summary of dynamic analytical methods for high-rise buildings in Japan. The following indispensable items for the dynamic analysis of skyscrapers are briefly introduced: Structural design criteria, analytical model, earthquake motion used for dynamic analysis, acquisition of earthquake ground motions, various dynamic analysis methods and its application range, and modal analysis.

Evaluation of Building Resilience under Earthquake Input Using Single, Double and Multiple Impulses

This eBook is the third in a series of books on the critical earthquake response of elastic or el... more This eBook is the third in a series of books on the critical earthquake response of elastic or elastic-plastic structures under near-fault or long-duration ground motions, and includes four original research papers which were published in the specialty section Earthquake Engineering in ‘Frontiers in Built Environment’. Several extensions of the first eBook and the second eBook are included here. The first article is on the earthquake resilience of residential houses after repeated ground motions with high intensity. The 2016 Kumamoto earthquake brought a significant impact on the earthquake resilience of residential houses under repeated ground motions with high intensity in a few days. The necessary strength upgrade withstanding two repeated high-intensity ground motions was found to be 1.5. The second article is concerned with the smart enhancement of earthquake resilience of building structures under both near-fault and long-duration ground motions. A hybrid system of base-isolation and building connection control was proposed and its earthquake resilience to near-fault and long-duration ground motions was evaluated by a double impulse and a multiple impulse. It was demonstrated that the base-isolation is effective for near-fault ground motions and the building connection system using passive dampers is effective for long-duration ground motions. The third article is related to the robustness evaluation of elastic-plastic base-isolated high-rise buildings under resonant near-fault ground motions. The robustness function was introduced to evaluate quantitatively the robustness of elastic-plastic base-isolated high-rise buildings. The fourth article is an extension of the previously proposed energy balance approach to a bilinear elastic-plastic single-degree-of-freedom system under a long-duration sinusoidal ground motion. A historical difficulty in nonlinear vibration posed by Caughey (1960) and Iwan (1961) has been overcome in a smart manner after half a century. The approach presented in this eBook, together with the previous eBooks, is an epoch-making accomplishment to open the door for simpler and deeper understanding of structural reliability and resilience of built environments in the elastic-plastic and nonlinear range

23298 Seismic Retrofit of Building Structures by Out-framed Viscous Damping System : Part 3 Experimental Study

Summaries of technical papers of Annual Meeting Architectural Institute of Japan. C-2, Structures IV, Reinforced concrete structures prestressed concrete structures masonry wall structures, Jul 31, 2006

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