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Tokyo, Japan

Kajima Corporation is a Japanese construction company. Founded in 1840, the company has its headquarters in Motoakasaka, Minato, Tokyo. The company is known for its DIB-200 proposal. The company stock is traded on four leading Japanese stock exchanges and is a constituent of the Nikkei 225 stock index.One of the five leading general contractors in Japan, that are also referred to as "super general contractor". As well as being one of the key opinion leaders, also from its top-class domestic construction revenue, it is seen as one of the leading companies in the construction industry in Japan. Corporate slogan is "Company that builds 100 years". Wikipedia.

Oka Y.,Yokohama National University | Imazeki O.,Kajima Corporation
Fire Safety Journal | Year: 2014

It is important to understand velocity and temperature distributions within a ceiling jet, because fire detectors operate within this region. Many researchers have worked positively to clarify ceiling jet properties by means of experimental and theoretical approaches, and sophisticated correlations have been developed to represent temperature and velocity distributions within the ceiling jet that flows under an unconfined, horizontal ceiling with smooth surface. Few studies focus on the ceiling jet that flows under an inclined ceiling. A series of pool fire tests are conducted using a smooth, unconfined model ceiling with varying inclination angles of up to 40°. Temperature distributions are measured using thermocouple rakes consisting of chromel-alumel with a strand wire diameter of 0.2 mm. Velocity distributions are also obtained using particle image velocimetry. On the basis of the measured data, empirical formulae to represent temperature and velocity distributions are developed by applying an exponential function that decays monotonically with the distance from the ceiling surface, and coefficients included in these formulae are represented as a function of the inclination angle of the ceiling. To verify the applicability of the developed formulae to an actual fire, they are compared with the full-scale test data and show a good agreement. © 2013 Elsevier Ltd. All rights reserved. Source

Takaoka E.,Kajima Technical Research Institute | Takenaka Y.,Kajima Corporation | Nimura A.,Kajima Technical Research Institute
Earthquake Engineering and Structural Dynamics | Year: 2011

This paper describes the results of shaking table tests to ascertain the ultimate behavior of slender base-isolated buildings and proposes a time history response analysis method, which can predict the ultimate behavior of base-isolated buildings caused by buckling fracture in laminated rubber bearings. In the tests, a base-isolated structure model weighing 192 kN supported by four lead rubber bearings is used. The experimental parameters are the aspect ratio of height-to-distance between the bearings and the shape of and the axial stress on the bearings. The test results indicate that the motion types of the superstructure at large input levels can be classified into three types: the sinking type; the uplift type; and the mixed type. These behaviors depend on the relationship between the static ultimate lateral uplifting force on the superstructure and the lateral restoring characteristics of the base-isolated story. In the analysis method, bearing characteristics are represented by a macroscopic mechanical model that is expanded by adding an axial spring to an existing model. Nonlinear spring characteristics are used for its rotational, shear, and axial spring. The central difference method is applied to solve the equation of motion. To verify the validity of the method, simulation analysis of the shaking table tests are carried out. The results of the analysis agree well with the test results. The proposed model can express the buckling behavior of bearings in the large deformation range. Copyright © 2010 John Wiley & Sons, Ltd. Source

Saito T.,Kajima Corporation
Journal of Magnetism and Magnetic Materials | Year: 2010

It was determined that a wall composed of aligned strips with gaps could achieve almost the same magnetic shielding effect as a conventional solid plate wall. This new shielding system is called the "open-type magnetic shielding method." This study reports the experimental results for the magnetic shielding effect of open-type magnetic shielding walls in comparison with conventional solid plates. The magnetic field generator of the experimental model is an approximately 1/15 scale reduced train system. The magnetic shielding structure is composed of a maximum of four walls around this train model. The magnetic flux density leakage from the structures was measured. In the case of multiple walls, the results show that the open-type magnetic shielding method has a little better shielding performance than the conventional method. © 2009 Elsevier B.V. All rights reserved. Source

Kamagata S.,Kajima Corporation | Takewaki I.,Kyoto University
Soil Dynamics and Earthquake Engineering | Year: 2013

The Suruga Bay earthquake in 2009 attacked the Hamaoka nuclear power station and stopped the operation. The maximum acceleration 4.38m/s2 at the foundation of the reactor building of No. 5 unit was four times larger than that of No. 1 unit. It was found that the vibration amplitude at 2.5Hz is mainly related to that maximum acceleration. The records in the underground support the fact that the vibration amplification was caused in the surface soil from 25 to 100m beneath the reactor building. The non-stationary Fourier spectra clarified that the frequency of the dominant component shifted from 3.0Hz to 2.5Hz in the short transient time. The dual-peak shape in the displacement profile was assumed to consist of the fundamental mode and the local vibration mode and this was identified by the dual Ricker wavelets. This identification indicates that the vibration amplification was caused by the deformation with the amplitude of 20mm in the underground. The average strain of soil from SRφ-22 (22m underground) to SRφ-100 (100m underground) reached 0.031% which reduced 30% of shear stiffness. The rocking mode of the foundation was further observed from the vertical deformation of the foundation. By investigating the phase of the displacement profile, it was found that the natural period at the north position was longer than that at the south position, which is related to the nonlinearity of the supporting soil. © 2013 Elsevier Ltd. Source

Oka Y.,Yokohama National University | Imazeki O.,Kajima Corporation
Fire Safety Journal | Year: 2015

In this study, we conducted detailed measurements of the temperature distribution within a steady fire-driven ceiling jet, formed in a tunnel with a rectangular cross-section. We then compared the measured temperature distributions with those for an unconfined smooth-ceiling jet flow, and estimated the relative errors between them. The results showed that the temperature distribution in a horizontal tunnel exhibits a greater bulge than that of a ceiling jet under an unconfined ceiling and varied from a bulging shape to an exponential shape as the tunnel inclination increased. We propose a new correlation for representing the temperature distribution, which takes the tunnel inclination into account, and which consists of an exponential function and a cubic function with a coordinated transformation. © 2014 Elsevier Ltd. All rights reserved. Source

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