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Kog Y.C.,West Japan Engineering Consultants Inc.
Journal of Performance of Constructed Facilities | Year: 2017

A 3-story building was found tilted badly as a result of a nearby deep excavation. Numerous cracks were developed on the façade walls and load-bearing brick walls. Dislodgement of some timber joists was observed at some parts of the second and third stories of the building. A detailed assessment of the conditions of the building was carried out. Unlike current prevailing practice, the assessment of damages caused by excavation-induced ground movements of this building includes tilts and out-of-plumbs of the load-bearing brick walls. The present study proposes to assume that the building behaves as a rigid body, and with appropriate empirical building correction factors to correct the inappropriateness of this assumption, reasonable estimates of the resulting out-of-plumbs of load-bearing brick walls of such buildings caused by a nearby deep excavation can be obtained. The empirically derived building correction factor is validated by comparing the predicted and measured out-of-plumbs of the brick wall of another 3-story masonry building affected by excavation. A new procedure for assessing damage potential to low-rise masonry buildings that includes tilt and out-of-plumb of brick walls caused by excavation is presented. © 2016 American Society of Civil Engineers.

Kaneko M.,West Japan Engineering Consultants Inc.
Journal of the Geothermal Research Society of Japan | Year: 2016

Geothermal energy laws in other countries may be great reference when Japan considers enhancing its own legal framework to promote geothermal energy development. This paper follows the previous paper of "Geothermal Energy Laws in the World" which was placed in the Journal of Geothermal Research Society of Japan, vol. 34, No.3 (2012). The previous paper surveyed geothermal energy laws of nine major geothermal countries including the U.S., the Philippines, New Zealand, Iceland and Japan. This paper is a supplemental paper to provide information of geothermal energy law of other countries such as Indonesia, Mexico, Italy, Turkey, Costa Rica, Peru and Ethiopia. The surveys show; (i) Each country has its own geothermal energy law to promote geothermal energy development. (ii) Hot Spring Law, that was enacted to regulate small wells for thermal baths, is also used to regulate large-scale wells for geothermal power plants in Japan. There are, however, many inconvenience arise from adapting Hot Spring Law to geothermal energy development. (iii) Japan needs to enact its own "Geothermal Energy Law," of which objective is to control and to promote geothermal energy development, with reference of other country's geothermal laws. © The Geothermal Research Society of Japan, 2016.

Kog Y.C.,West Japan Engineering Consultants Inc. | Loh P.K.,National University of Singapore
Journal of Construction Engineering and Management | Year: 2012

The present study attempts to distinguish the different critical success factors (CSFs) for different components of construction projects as perceived by different professions, i.e.,civil and structural engineers, mechanical and electrical engineers, architects, and quantity surveyors. An analytical hierarchy process (AHP) is adopted to solicit the consistent subjective judgment of 27 experts in construction to identify the top 10 CSFs from 67 factors describing aspects of project characteristics, contractual arrangements, project participants, and interactive processes. The views of the different professionals are shaped by the experience they gained from their involvement in the respective components of the construction projects under their charge. It follows that the CSFs identified by the professionals are naturally relevant to the components of construction projects that they are familiar with. The present study reveals that the respective top 10 CSFs for the schedule, budget, and quality performance of architectural works, civil and structural works, and mechanical and electrical engineering works are markedly different. Moreover, the study shows that the judgment with regard to CSFs of respondents with less than 15years of experience differs from that of the more experienced respondents and hence may not be good enough. It follows that studies reported in the existing literature that have included views of respondents with less than 15years' experience in construction or based on the views of professionals predominantly from a particular discipline are likely to be biased and misleading. © 2012 American Society of Civil Engineers.

Kog Y.C.,West Japan Engineering Consultants Inc.
International Journal of Geomechanics | Year: 2016

The interaction of an applied axial load and a drag load on a circular pile in consolidating layered soil is investigated. A rigorous load-transfer theory with elastoplastic slip considered at the pile-soil interface for such piles is developed. The validity of the proposed solution is confirmed by a comparison with field measurements. Results of extensive parametric studies with regard to the pile behavior are presented for a better understanding of the behavior for axially loaded piles embedded in layered soil with an upper consolidating layer. Design charts are presented to predict the location of the neutral plane, maximum pile load, and pile top settlement for axially loaded piles in layered consolidating soils. © 2015 American Society of Civil Engineers.

Kog Y.C.,West Japan Engineering Consultants Inc.
Journal of Performance of Constructed Facilities | Year: 2014

A completed car park canopy collapsed shortly after its completion. The structural system of the car park canopy was a T steel structure of unequal cantilevers connected to the ground at the base with eight 25-mm anchor bolts. The collapse was a progressive one starting with the steel structure located at one end of the roof. An investigation of the causes of collapse was carried out. Before the collapse, the maximum tension acting on an anchor bolt was not more than 10% of the tensile strength of the bolt. This investigation shows that the use of incompatible bolts and nuts such as in the case reported lead to the total loss of the tension capacity of anchor bolts in 3 days. © 2014 American Society of Civil Engineers.

Yahara T.,West Japan Engineering Consultants Inc. | Tokita H.,West Japan Engineering Consultants Inc.
Geothermics | Year: 2010

The Hatchobaru power plant Unit No. 1 (55. MW) has been operating since 1977 and Unit No. 2 (55. MW) since 1990. The mean capacity factor of the power plant has reached about 90%. Considering that the long-term operation of the plant, over 30 years for Unit No. 1 and nearly 20 years for Unit No. 2, has been maintained with such a high capacity factor, sustainable development in terms of economic production has been achieved. To maintain a stable operation, systematic reservoir monitoring and reservoir simulation studies have been conducted. The monitoring of changes in reservoir pressure, temperature and gravity indicates that the reservoir is currently approaching a stable state. Results of a simulation study suggest that the sustainable power output of the Hatchobaru reservoir is approximately 120. MW, and each productive fault has the capacity to produce enough steam to generate from 11 to 55. MW. Therefore, it would be possible to maintain the rated power output of 110. MW by optimizing well alignments so that the mass production can be kept within the sustainable productivity of each fault, and the injected water does not cool the production zones. © 2010.

Kog Y.C.,West Japan Engineering Consultants Inc.
Journal of Architectural Engineering | Year: 2016

Geotechnical engineers have reported that, in the foundation design of buildings with a deep basement, the weight of the soil removed for basement construction could be discounted from the foundation load. Substantial savings were achieved for a 22-story office building with a 2-level basement, for which the design of the pile foundation utilized this concept of compensated foundation. Subsequent site monitoring of selected column settlements showed that the total and differential settlements, angular distortion, and deflection ratio of the building were well within the allowable limits. Detailed information on the compensated foundation design is presented. © 2016 American Society of Civil Engineers.

Kog Y.C.,West Japan Engineering Consultants Inc.
Journal of Performance of Constructed Facilities | Year: 2010

This paper presents a detailed study to ascertain the response of a buried minor sewer pipeline consisting of three new manholes of 3.5- to 4-m deep and 89.7 m of 225-mm-diameter vitreous clay pipes to braced excavation ground movements. The pipeline and the manholes were supported on 6-m long, generally, of 65- to 75-mm-diameter Bakau (timber) piles embedded in 8- to 15-m-thick soft marine clay and peaty clay with an overconsolidation ratio of 1.2. The 34-m pipeline connecting two of the manholes ran parallel to a row of sheetpiles 9 m away. The sheetpiles formed one side of a strutted basement excavation about 9- to 10.5-m-deep. The excavation is part of an adjacent construction project. A recent oversite fill of 1.1 m has been placed to raise the site platform to avoid possible flooding throughout the area encompassing the pipeline and the adjacent construction project. Useful lessons which have been learnt from the study will be presented also. © 2010 ASCE.

Kog Y.C.,West Japan Engineering Consultants Inc.
Magazine of Concrete Research | Year: 2012

One of the most important tasks in the appraisal of an existing concrete structure is to establish the characteristic in situ strength for checking the structural adequacy of the structure for its intended usage. Existing codes of practice on the assessment of in situ concrete strength have addressed most of the important issues for carrying out this task, but one of the gaps is the appropriate size for the random sample. The approach taken by the codes at present is to leave this important decision to the judgement of engineers. This is not satisfactory. This paper presents a statistical study using a non-parametric method based on order statistics to establish the appropriate sample size of cores and non-destructive tests for determining in situ concrete strength. The statistical study reveals a relationship for the size of the random sample so that a desired fraction of the sample yields in situ strengths in a required range with a desired probability. An example is included to show the application of this relationship to determine sample size for the assessment of in situ strength for a multi-storey concrete building.

Kog Y.C.,West Japan Engineering Consultants Inc.
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2015

Axially loaded piles installed in layered soils where the upper soil layer is still consolidating are subjected to the combined interactive action of axial load and drag load. The shift of the location of the neutral plane as a result of the interaction of the axial load and drag load leads to the possibility that such piles need not account for the negative skin friction in determining the maximum pile force for the pile structural design. The results of a series of centrifuge tests on axially loaded piles in consolidating layered soil are presented so that the effect of negative skin friction on pile settlements and locations of the neutral plane of such piles can be better understood. The criteria regarding whether negative skin friction needs to be accounted for in determining the maximum pile force for the pile structural design are established in the present study based on centrifuge test results and findings reported in the literature. © 2015, Thomas Telford Services Ltd. All rights reserved.

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