Search

Your search keyword '"Takewaki, Izuru"' showing total 966 results
Start Over Author "Takewaki, Izuru"
966 results on '"Takewaki, Izuru"'

469. This title is unavailable for guests, please login to see more information.

Author

FUJITA, Kohei, TAKEWAKI, Izuru, 40648713, 20155055, FUJITA, Kohei, TAKEWAKI, Izuru, 40648713, and 20155055

Abstract

An efficient methodology is presented to evaluate the robustness (variability of response) of an uncertain base-isolated building. While a basic assumption of "inclusion monotonic" is introduced in usual interval analysis, the possibility is taken into account of occurrence of the extreme value of the objective function in an inner feasible domain of the interval parameters. It is shown that the critical combination of the structural parameters can be derived explicitly so as to maximize the approximate objective function by 2nd-order Taylor series expansion. The URP (Updated Reference-Point) method is proposed to obtain such critical combination of structural parameters. In order to investigate the validity of the proposed robustness evaluation methodologies, numerical analyses are conducted for 20-storey base-isolated building models with natural rubber isolators and passive dampers. By comparing the results with the exact solution and those by other conventional methods, it is shown that the URP method can provide a more accurate evaluation of response bounds without hard computational effort.

Published
2011

471. This title is unavailable for guests, please login to see more information.

Author

ADACHI, Fuyuki, YOSHITOMI, Shinta, TSUJI, Masaaki, TAKEWAKI, Izuru, 20155055, ADACHI, Fuyuki, YOSHITOMI, Shinta, TSUJI, Masaaki, TAKEWAKI, Izuru, and 20155055

Abstract

An advanced reduced model is proposed for elastic earthquake response analysis of shear building structures with setback. The proposed reduction method consists of two parts. The first stage is the construction of a reduced structural model with the degrees of freedom at representative floor levels only. The reduced model is constructed using an inverse eigenmode-problem formulation so as to have the same fundamental natural frequency and lowest-mode component ratios at the representative floor levels as the original model. The second stage is the transformation of earthquake input forces into a set of reduced input forces. This transformation is introduced to enhance the accuracy level of the reduced model.

Published
2011

479. This title is unavailable for guests, please login to see more information.

Author

TSUJI, Masaaki, TANAKA, Hidetoshi, YOSHITOMI, Shinta, TAKEWAKI, Izuru, 20155055, TSUJI, Masaaki, TANAKA, Hidetoshi, YOSHITOMI, Shinta, TAKEWAKI, Izuru, and 20155055

Abstract

A model reduction method is proposed for an elastic high-rise building with viscous dampers subjected to earthquake ground motion. A set of story stiffnesses of the reduced model is found under the equivalent conditions that the original model without dampers and its reduced model possess the same fundamental natural frequency and fundamental mode shape. A reduced model of the time-dependent earthquake inertia force is also proposed by requiring the equivalence of displacements at representative floor levels in both models without inertia and damping terms. A set of damping coefficients and a set of relief loads of bilinear-type viscous dampers of the reduce model are found under the equivalent conditions that the original model with dampers and its reduced model possess the same lowest-mode damping ratio and energy dissipation mode shape. Numerical examples are presented to demonstrate the efficiency and accuracy of the proposed method. It is concluded that the proposed method can substantially reduce the number of degrees of freedom in the time history analysis within an acceptable accuracy.

Published
2011

480. This title is unavailable for guests, please login to see more information.

Author

MAEDA, Tomohiro, YOSHITOMI, Shinta, TAKEWAKI, Izuru, MAEDA, Tomohiro, YOSHITOMI, Shinta, and TAKEWAKI, Izuru

Abstract

In this paper, a stiffness-damping identification method for a building structure is proposed when the building is subjected to earthquake ground motion. The difficulty arising in the limit manipulation in the previous method is overcome by introducing an ARX model. The weakness of small SN ratio in the low frequency range is avoided by using the ARX model and introducing new constraints on the ARX parameters. The validity of the proposed method is examined through numerical examples using simulated data and actually recorded data.

Published
2011

496. Preliminary report of the 2011 off the Pacific coast of Tohoku Earthquake

Author

20155055, Takewaki, Izuru, 20155055, and Takewaki, Izuru

Abstract

On March 11, 2011, eastern Japan was shaken by the 2011 off the Pacific coast of Tohoku Earthquake (the Great East Japan Earthquake). Almost 30 000 people have been killed or are missing as a result of that earthquake and the subsequent monster tsunami, as of April 11, 2011. This paper reports several aspects of this devastating earthquake. It has been reported that long-period ground motions, which had been predicted by many researchers, occurred in Tokyo, Nagoya and Osaka. The response characteristics of high-rise buildings to the recorded long-period ground motions are discussed from the viewpoint of resonance and critical excitation. It is shown that high-hardness rubber dampers are very effective in the reduction of vibration duration in addition to the reduction in vibration amplitude.

Published
2011

497. Enhanced reduced model for elastic earthquake response analysis of a class of mono-symmetric shear building structures with constant eccentricity

Author

00243121, 20155055, Adachi, Fuyuki, Yoshitomi, Shinta, Tsuji, Masaaki, Takewaki, Izuru, 00243121, 20155055, Adachi, Fuyuki, Yoshitomi, Shinta, Tsuji, Masaaki, and Takewaki, Izuru

Abstract

An enhanced reduced model is proposed for elastic earthquake response analysis of a class of mono-symmetric shear building structures with constant eccentricity. The proposed reduction method consists of two parts. The first stage is the construction of a reduced structural model with the degrees of freedom at representative floor levels only. In this stage, an inverse eigenmode-problem formulation is used to guarantee the limited equivalence between the original model and the reduced model. The reduced model is constructed so as to have the same fundamental natural frequency and the same lowest-mode component ratios at the representative floor levels as those of the original model. The second stage is the transformation of earthquake input forces into a set of reduced input forces. This transformation utilizes the static equivalence of lateral-torsional stiffness between these two models and is introduced to enhance the accuracy level of the reduced model. Several examples of a three-dimensional mono-symmetric ten-story shear building model with constant eccentricity are presented to demonstrate the validity and accuracy of the proposed reduction method for earthquake response analysis.

Published
2011

498. This title is unavailable for guests, please login to see more information.

Author

Yamamoto, Kaoru, Fujita, Kohei, Takewaki, Izuru, 40648713, 20155055, Yamamoto, Kaoru, Fujita, Kohei, Takewaki, Izuru, 40648713, and 20155055

Abstract

This paper aims to obtain an optimal viscous damper placement for building structures using H∞ optimization. The H∞ norm of the transfer function matrix is adopted as the objective function. Since it represents the magnitude of vibration transfer, one can attenuate the gain of the frequency response by minimizing this norm. The sequential quadratic programming (SQP) method is employed for optimization. The proposed method is also applicable to a various structural models as well, e.g., a bending-shear building model and a framed structure model. Numerical examples are presented to demonstrate the effectiveness of the proposed design method.

Published
2010

499. This title is unavailable for guests, please login to see more information.

Author

TSUJI, Masaaki, KOKUBU, Hiroki, YOSHITOMI, Shinta, TAKEWAKI, Izuru, 00243121, 20155055, TSUJI, Masaaki, KOKUBU, Hiroki, YOSHITOMI, Shinta, TAKEWAKI, Izuru, 00243121, and 20155055

Abstract

A set of reduced models of structures and earthquake loads is proposed for a high-rise building under earthquake ground motions. A reduced structural model is constructed first based on an inverse problem formulation in terms of fundamental eigenfrequency and eigenmode. Then a reduced model of earthquake loads is proposed by requiring the equivalence of displacements at representative nodes in the frame model and the reduced model without inertial and damping terms. These reduced models are used in developing an optimum placement method of nonlinear dampers in high-rise buildings under earthquake ground motions. Numerical response sensitivity by the proposed reduced model is taken full advantage in the optimum placement method. The validity of the proposed method is investigated by the comparison with the results by the original full model.

Published
2010

Catalog

Books, media, physical & digital resources
See catalog results