Concrete Journal
Online ISSN : 2186-2753
Print ISSN : 0387-1061
ISSN-L : 0387-1061
Volume 52, Issue 2
Displaying 1-15 of 15 articles from this issue
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  • H. Araki, M. Neguchi, K. Minami
    2014 Volume 52 Issue 2 Pages 151-156
    Published: 2014
    Released on J-STAGE: February 01, 2015
    JOURNAL FREE ACCESS
    Seismic evaluations of existing RC buildings have been extensive in Japan since the earthquake of 1995. According to some reports, seismic evaluations found many RC buildings of very low concrete strength, i.e. less than half of the design concrete strength. It is necessary for evaluation and retrofitting to clarify the mechanical characteristics of low strength concrete and seismic performance of low strength concrete members and frames. This report presents the results obtained from experimental studies on low strength concrete. In conclusion, the importance of investigating the characteristics of existing buildings before retrofitting them needs to be emphasized and made a standard practice.
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  • H. Yokota, K. Kawai
    2014 Volume 52 Issue 2 Pages 157-164
    Published: 2014
    Released on J-STAGE: February 01, 2015
    JOURNAL FREE ACCESS
    This paper explains the outline of the revisions made to the JSCE Standard Specifications for Concrete Structures 2013, Maintenance. While adhering to the basic maintenance concept of the 2007 edition, the 2013 edition has changed the basic configuration to align it more with that of a performance verification system. In addition, new knowledge has been incorporated, including the introduction of maintenance limits, the performance evaluation of existing structures, and the introduction of maintenance based on deterioration phenomena, and various other revisions have been made to make these specifications even more useful for the practice of maintenance.
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  • K. Uji, M. Kondo, T. Tsutsumi, T. Sasaki, T. Ayano, K. Iriya
    2014 Volume 52 Issue 2 Pages 165-170
    Published: 2014
    Released on J-STAGE: February 01, 2015
    JOURNAL FREE ACCESS
    The 2013 edition of the “Dam Concrete” volume consists two parts, “General Requirements” and “Standard Methods”. The newly renamed “General Requirements” has undergone major revisions. Considering the flow from the structural design of concrete dams to their actual construction, a construction planning chapter has been newly added as content that is common to design and construction, and the other chapters were also revised from the viewpoint of their role for performance verification. Passages that featured somewhat difficult to understand or special terminology and expressions have been revised to make them as plain and straightforward as possible. With regard to thermal cracking, the relationship between restraint strain using the restraint intensity matrix method, and the cracking index using the finite element model, was examined and the findings have been incorporated in the revised materials. A review of the influence of minerals, an aspect that requires attention to ensure the physical stability of aggregate, was conducted, and the publication of control standard values was abandoned in favor of the description of appropriate usage methods.
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  • M. Mizuno, T. Iwao
    2014 Volume 52 Issue 2 Pages 171-178
    Published: 2014
    Released on J-STAGE: February 01, 2015
    JOURNAL FREE ACCESS
    Expressway companies in Japan have developed middle performance concrete that uses stone powder and coal ash and compiled Construction Management Guidelines for it in August 2008. Stone powder and coal ash, however, do not satisfy the standard specifications for middle performance concrete owing to various factors including current distribution conditions and plant facility limitations. We, therefore, conducted studies to verify the properties and quality of middle performance concrete, using an admixture whose quality and availability do not depend on local conditions and reached a conclusion that such concrete is applicable as a standard material for highway tunnels. Furthermore, to evaluate the long-term durability of middle performance concrete, we also carried out a follow-up study of the middle performance concrete that uses coal ash and limestone fines, after construction, and found the concrete to be of greater density and higher quality than ordinary lining concrete.
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