Search

SUMMARY A new method of system identification of high-rise buildings is proposed in which high-rise buildings are represented by a shear-bending model. The method is devised to find the story shear and bending stiffnesses of a specific story from the horizontal floor accelerations. The special characteristic of the proposed method is to use a previously derived set of closed-form expressions for the story shear and bending stiffnesses in terms of the limited floor accelerations and to utilize a reduced shear-bending model with the same number of elements as the vibration recording points. In the proposed method, a difficulty of prediction of an unstable specific function in a low-frequency range can be overcome by introducing an ARX model. It is demonstrated that the shear-bending model can simulate the vibration records with a reasonable accuracy. It is shown further that the vibration records at two super high-rise buildings during the 2011 Tohoku (Japan) earthquake can be simulated with the proposed method including a technique of adding degrees of freedom between the vibration recording points. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY A new method of system identification and damage detection of high-rise buildings is proposed in which high-rise buildings are represented by a shear-bending model. The method is devised to find the story shear and bending stiffnesses of a specific story from the floor accelerations just above and below the specific story. The special characteristic of the proposed method is to derive a set of closed-form expressions for the story shear and bending stiffnesses in terms of the limited floor accelerations. It is demonstrated that the method is suitable for the damage detection because the observation of floor accelerations at two stories is a simple task and damage detection can be performed directly from the change of a specific function of frequency at zero frequency. It is shown that a difficulty of prediction of the specific function in a low frequency range can be overcome by introducing an ARX (Auto-Regressive model with eXogenous input) model with constraints on transfer functions. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Fundamental mechanisms of earthquake response reduction in building structures with inertial mass dampers are investigated. The inertial mass damper is effective with respect to relative acceleration between two nodes. The influence of inertial mass dampers on the ground-motion input can be expressed by the influence coefficient vector to be multiplied on the ground-motion acceleration in the right-hand side of the equations of motion. It is shown that, when an inertial mass damper is taken out from one story, the component of the influence coefficient vector above that story becomes 1. This means that, if an inertial mass damper is taken out from one story, the inertial mass dampers above that story do not influence the input acceleration above that story. This observation is supported by the closed-form expression of the influence coefficient vector. The mechanism of earthquake response reduction is also discussed from the viewpoint of earthquake input energy. It is shown that the earthquake input energy under an acceleration input with a constant Fourier spectrum depends on the influence coefficient vector. Finally, the characteristics of earthquake response reduction via inertial mass dampers are presented for three recorded ground motions. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

High-hardness viscoelastic rubber dampers are used to upgrade both the habitability environment and the structural safety in high-rise buildings subjected to wind disturbances. While most of usual viscoelastic dampers have limitation on temperature and frequency dependencies, etc., the proposed high-hardness viscoelastic rubber dampers possess many unprecedented properties. High hardness, large stiffness, small temperature and frequency dependencies are examples of such properties. Mechanical modelling of the proposed high-hardness viscoelastic rubber dampers is introduced first, and the wind-induced response of high-rise buildings with and without the proposed high-hardness viscoelastic rubber dampers is computed under dynamic horizontal loads derived from wind tunnel tests. It is shown that high-rise buildings with the proposed high-hardness viscoelastic rubber dampers exhibit extremely smaller wind-induced responses (both along-wind and cross-wind responses) than those without such dampers. In particular, a remarkable reduction of acceleration has been achieved owing to sufficient hysteresis even in the small strain range. It is concluded that the proposed high-hardness viscoelastic rubber dampers can upgrade the habitability environment of building structures dramatically. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to propose a simple analysis method of axial deformation of base-isolation rubber beatings in a building subjected to earthquake loading and present its applicability to the analysis of the bound of the aspect ratio of base-isolated buildings. The base shear coefficient is introduced as a key parameter for the bound analysis. The bound of the aspect ratio of base-isolated buildings is analyzed based on the relationship of the following four quantities; (i) ultimate state of the tensile stress of rubber beatings based on a proposed simple recursive analysis for seismic loading, (ii) ultimate state of drift of the base-isolation story for seismic loading, (iii) ultimate state of the axial compressive stress of rubber beatings under dead loads, (iv) prediction of the overturning moment at the base for seismic loading. In particular, a new recursive analysis method of axial deformation of rubber beatings is presented taking into account the nonlinear tensile behavior of rubber bearings and it is shown that the relaxation of the constraint on the ultimate state of the tensile stress of rubber bearings increases the limiting aspect ratio. [ABSTRACT FROM AUTHOR]

A detailed anatomical analysis of the left brachial plexus, composed of the fourth cervical to first thoracic spinal nerve roots, was performed in an adult male orangutan obtained from the Osaka Museum of Natural History. Although the medial and posterior cords fused into a common trunk, a nerve fibre analysis revealed that the cords were not actually connected. A superficial branch (Rs) running ventral to the musculocutaneous nerve (MC) and a deep branch (Rp) running dorsal to the MC innervated the coracobrachialis muscle, which was also innervated by coracobrachialis branches (Rmc) from the MC. Koizumi (1989 : Acta Anat. Nippon, 64, 18) reported that the Rmc and Rs innervated the superficial region of the coracobrachialis muscle corresponding to superficial coracobrachialis muscle in prosimians, whereas the Rp innervated the deep region. However, the detailed innervation of the coracobrachialis muscle in orangutans was not included in Koizumi and Sakai's (1995 : J. Anat. 186, 395) report. Our observations in an orangutan did not seem to support generalisation, because the common trunk of the Rp and Rmc appeared to innervate both the superficial and deep regions of the coracobrachialis muscle. Therefore, a nerve fibre analysis of the common trunk was performed as a detailed examination. The analysis confirmed that the Rp in the orangutan only innervated the deep region of the coracobrachialis muscle, similar to the innervation pattern seen in other apes and humans. [ABSTRACT FROM AUTHOR]

A new experimental system of base-isolated structures is proposed. There are two kinds of dampers usually used in the base-isolated buildings, one is a viscous-type damper and the other is an elastic-plastic hysteretic-type damper. The base-isolated structure with a viscous damper and that with an elastic-plastic hysteretic damper are compared in this paper. The viscous damper is modeled by a mini piston and the elastic-plastic hysteretic damper is modeled by a low yield-point steel. The capacity of both dampers is detennined so that the dissipated energies are equivalent at a specified deformation. When the capacity of both dampers is determined according to this criterion, it is shown that the response of the base-isolated structure with the elastic-plastic hysteretic damper is larger than that with the viscous damper. This characteristic is demonstrated through the comparison of the bound of the aspect ratio. It is shown that the bound of aspect ratio for the base-isolated structure with the elastic-plastic hysteretic damper is generally smaller than that with the viscous damper. When the base-isolated structure is subjected to long-duration input, the mechanical property of the elastic-plastic hysteretic damper deteriorates and the response of the base-isolated structure including that damper becomes larger than that with the viscous damper. The effect of this change of material properties on the response of the base-isolated structure is also investigated. [ABSTRACT FROM AUTHOR]