Concrete Journal

Remodel for Postwar School Building

Yasuhiko Nagakura, Reiji Tanaka

1993 Volume 31 Issue 9 Pages 5-17
Published: September 01, 1993
Released on J-STAGE: April 26, 2013

DOIhttps://doi.org/10.3151/coj1975.31.9_5

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It has already been forty years since the first postwar reinforced concrete school buildings were built in Japan. Over ninety percent of these buildings have the same balcony type structure, which have been criticized for their boring (non-characteristic) plain-site and block-plan, as well as functional problems that come from repeated “BARADATE”. (Baradate refers to a practice of site planning of a new building that continuously adds to existing buildings based solely on space demand, without considering a more rational longer-term plan for expanding the use of the space.) For the last ten years uniformity in the Japanese educational system has been gradually changing to a more diverse system that characterizes the several aspects of Japanese educational revolution. As a part of it, site planning of school buildings needs to be improved. Earthquakes in the past have also shown the structural problems of postwar reinforced concrete school buildings need to be addressed. This paper covers these issues and discusses the necessity to create a “reconstruction system for postwar reinforced concrete school buildings” that is expected to take the next several decades to complete. This paper proposes its method in terms of both the theory of planning and design and also of structural design for seismic safety. At the end of the paper, we discuss the outstanding issues that need to be studied.

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Belite Portland Cement

-Application to Low Heat and Super Workable High Strength Concrete-

M. Tanaka, H. Harada, T. Nawa, T. Tochigi

1993 Volume 31 Issue 9 Pages 18-27
Published: September 01, 1993
Released on J-STAGE: April 26, 2013

DOIhttps://doi.org/10.3151/coj1975.31.9_18

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In Japan, cement companies have produced three types of clinker for ordinary, early high strength and moderate heat portland cement for many years. These clinkers have been ground with gypsum and/or mineral additives such as blastfurnace slag and fly ash, and supplied in aforesaid portland cements and blended cements. In recent years, however, concrete constructions have become larger and higher and are demanding high performance concrete with lower heat, far greater workability, high strength and durability. With these points as background, research and development on belite portland cement, in which more belite is contained than in moderate heat portland cement, is being carried out and its effectiveness on thermal, rheological and strength properties is being recognized. The basic properties of belite portland cement are explained here and its quality as cements for low heat and super workable high strength concrete is introduced, together with its application to actual constructions.

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A Practical Method for Computing Redundant Force of Partially Prestressed Concrete Structures Considering Reduction of Rigidity due to Cracking

Minoru Inomata

1993 Volume 31 Issue 9 Pages 28-32
Published: September 01, 1993
Released on J-STAGE: April 26, 2013

DOIhttps://doi.org/10.3151/coj1975.31.9_28

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In designing statically indeterminate structures of partially prestressed concrete under service load conditions, it is reasonable to take into account reduction of flexural rigidity due to cracking for computing member forces. A practical method for computing redundant force is presented here, because nonlinear analysis considering reduction of rigidity due to cracking is complex for design practices. By using this method, numerical calculations of the partially prestressed concrete continuous girder bridges are tried. The results agree with the value obtained by the nonlinear analysis.

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Construction of Highrise Condominium Buildings using Newly Developed Precast Framed Wall Structural System

R. Ishibashi, H. Takada, M. Tanaka, S. Ikeda

1993 Volume 31 Issue 9 Pages 33-42
Published: September 01, 1993
Released on J-STAGE: April 26, 2013

DOIhttps://doi.org/10.3151/coj1975.31.9_33

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The development of precast concrete structural systems for highrised apartment houses has spread wide in response to social demand. Among those systems, newly developed Precast Framed Wall Structural System (abbr. WR-PC System) is remarkable because of its potential high performance for cost, quality, construction period, productivity and safety. This system has been developed in cooperation with The Housing and Urban Development Corporation, Kudan Architectural Institute, and Japan Prefabricated Construction Supplies and Manufacturers Association. This report describes the characteristics of the construction work of the condominiums in Sintokorozawa, where the newest WR-PC System was applied to evaluate its efficiency.

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The Design and Construction of the Five-Story Junction

--Bijogi Junction--

Shuji Tomizawa, Akira Saito

1993 Volume 31 Issue 9 Pages 43-52
Published: September 01, 1993
Released on J-STAGE: April 26, 2013

DOIhttps://doi.org/10.3151/coj1975.31.9_43

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Bijogi Junction is located at Bijogi in Toda city, and is a connecting point of both the Metropolitan Expressway and the Tokyo Outer-Ring Route. This junction has five floors, including the underpass of the Sin-Omiya Bypass. The diaphragm wall foundation was adopted to support the five-story structure due to the requirements of the construction site. Both the specialities in the structural system and the severe site conditions required wide examinations and investigations on the design and the construction of the structure. This paper reports a general idea of the design of foundation and the consideration on aesthetic.

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Repair Work of Pier by Ultra High

-Strength Concrete

T. Masuda, Y. Matsunaga, Y. Watanabe

1993 Volume 31 Issue 9 Pages 53-61
Published: September 01, 1993
Released on J-STAGE: April 26, 2013

DOIhttps://doi.org/10.3151/coj1975.31.9_53

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Repair work on damaged Oyashirazu viaduct of Hokuriku Highway, which is located at the seashore, is reported. The repair work was conducted using ultra high-strength concrete (1000 kgf/cm²). Abrasion-resistance, penetration depth of Cl-ion and morphology of concrete are studied, using experimentally-made specimens and those from the practical structure, and the durability of ultra high-strength concrete is discussed.

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[title in Japanese]

[in Japanese]

1993 Volume 31 Issue 9 Pages 76-81
Published: September 01, 1993
Released on J-STAGE: April 26, 2013

DOIhttps://doi.org/10.3151/coj1975.31.9_76

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[title in Japanese]

[in Japanese]

1993 Volume 31 Issue 9 Pages 82-85
Published: September 01, 1993
Released on J-STAGE: April 26, 2013

DOIhttps://doi.org/10.3151/coj1975.31.9_82

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