Updated on 2024/03/30

写真a

 
YAMAZAKI,Masahiro
 
Organization
Faculty of Environmental and Urban Engineering Professor
Title
Professor
External link

Degree

  • Doctor of Engineering ( Kyoto University )

Research Interests

  • foundation engineering

  • 基礎構造

Research Areas

  • Social Infrastructure (Civil Engineering, Architecture, Disaster Prevention) / Building structures and materials

Research History

  • Kansai University   Professor

    2021.4

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  • Okayama University of Science   Professor

    2011.4 - 2021.3

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  • Okayama University of Science   Professor

    2010.4 - 2011.3

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  • Okayama University of Science   Associate Professor (as old post name)

    2006.4 - 2010.3

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Professional Memberships

Papers

  • Toe bearing behaviors of large diameter piles estimated by loading tests of small diameter piles Reviewed

    Hiroaki Nagaoka, Masahiro Yamazaki

    Soils and Foundations   39 ( 2 )   119 - 130   1999

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Japanese Geotechnical Society  

    A method to estimate the load-settlement relation at the toe of a large diameter pile is presented. Input information is the load-settlement relation of the toe of a small diameter pile obtained by loading test. First, soil parameters and coefficient of earth pressure at rest are determined as a set of plural solutions by back analysis, using finite element method of elastic-plastic soil and genetic algorithm. Since the input information is the load-settlement relation alone, soil parameters and so on can not be determined uniquely. Using the sets, finite element analyses are carried out which calculate load-settlement relations at the toe of a large diameter pile. Since the sets are plural, plural relations are obtained which determine the possible region of the relation. If a loading test for the large diameter pile is carried out, the load-settlement relation at the toe of the pile will coincide with one of the relations in the region. The load test results of large and small diameter concrete blocks which were constructed beneath the pile toes are analyzed. Using the tests result from the small diameter block, the possible region of the relation of the large diameter block is estimated and it is confirmed that the test results of the large diameter block is within the estimated region and the method is effective.

    DOI: 10.3208/sandf.39.2_119

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  • STUDY ON CHARACTERISTICS OF PILE END BEARING CAPACITY ON THIN BEARING LAYER (PART 2): INVESTIGATION ON BEARING CAPACITY MECHANISM BY MODEL PILE TEST

    YAMAZAKI Masahiro

    Journal of Structural and Construction Engineering (Transactions of AIJ)   86 ( 779 )   77 - 87   2021

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    Language:Japanese   Publisher:Architectural Institute of Japan  

    The pile end bearing capacity is reduced when the pile is constructed on the thin bearing layer overlying clay layer. This paper focuses on the bearing capacity mechanism based on the results of the model pile test. The soil tank of the test is semi-cylindrical. The side of the tank is constituted by a semi-cylindrical steel plate and a flat acrylic board. The ground displacement can be observed through the acrylic board. In addition of the pile load and settlement, the ground displacement as photograph and the horizontal earth pressure in the thin bearing layer were recorded. These records were shown in the following figures. (1) distribution of the ground vertical displacement (2) distribution of the ground maximum shear strain (3) pile load and the settlement relationship and the horizontal earth pressure and the settlement relationship.

     The figures (1) and (2) lead to the recognition that there are two types of the bearing capacity mechanism. The one occurs if <i>H<sub>s</sub></i>/<i>d</i> is 3 or more (<i>H<sub>s</sub></i> is the thickness of the bearing layer. <i>d</i> is the pile diameter.), and is that the shear strain zone stays around the area below the pile end and does not develop. The other occurs if if <i>H<sub>s</sub></i>/<i>d</i> is 2 or less, and is that the shear strain develops downward vertically from the pile end outside to the clay layer. The latter is punching failure that the cylindrical shear strain zoon makes a columnar ground which moves downward with the pile. The bearing capacity of the punching failure is the sum of the shear resistance force of the columnar ground side surface and the base resistance force from the clay layer.

     The figure(3) shows the phenomena that the pile load reduction and horizontal earth pressure reduction occur at almost the same settlement. It can be explained by the punching failure model because of the strong relation between the shear resistance force of the columnar ground side surface and the horizontal earth pressure. The explanation enhances the existence of the punching failure.

    DOI: 10.3130/aijs.86.77

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    Other Link: http://id.ndl.go.jp/bib/031234753

  • VERTICAL BEARING CAPACITY OF SANDY GROUND REINFORCED WITH EXPANSION STEEL PIPE PILE

    KUROYANAGI Nobuyuki, ITO Atsushi, YAMAZAKI Masahiro

    Journal of Structural and Construction Engineering (Transactions of AIJ)   86 ( 779 )   89 - 96   2021

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    The authors have proposed a new ground reinforcement method using expansion steel pipe piles, which expand diameter from 36 mm to 54 mm by injecting high pressure water into a steel pipe deformed into the heart shape and sealed the both ends. The proposed method aims to increase the bearing capacity of the small building foundation, and to prevent the differential settlement of a small building on poor sandy ground.

     In continuation of the research, this study focused on using the expansion steel pipe piles in composite ground, and vertical loading tests were carried out at both an artificial site and two natural sites composed of sandy soil.

     The ground at the artificial site was prepared by backfilling sandy soil into a pit with dimensions of 1500 mm width, 4250 mm length and 2300 mm depth. In addition, two natural sites consisting mainly of sandy soil were selected and loading tests were conducted at five locations in each.

     At the artificial site, comparison experiments were conducted in order to investigate the settlement behavior and bearing capacity of composite ground containing simple steel pipe piles with the same diameter as the expansion steel pipe piles. At the natural sites, the effect of ground reinforcement was confirmed by changing the size and shape of the foundation and the number of expansion steel pipe piles. In addition, FEM analysis using the artificial site as a model was performed and the effect of the expansion steel pipe piles on improving the ground bearing capacity was investigated. The findings obtained in this study are as follows:

     1) At the artificial site (average converted N-value of 2.6), results from the loading tests on composite ground containing simple steel pipe piles show that the ultimate bearing capacity of the composite ground was equal to the sum of the ultimate bearing capacity of the piles and that of the ground. However, in the case of composite ground containing expansion steel pipe piles the ultimate bearing capacity was 15% higher than the sum of the ultimate bearing capacity of the piles and that of the ground.

     2) At the natural sites (average converted N-values of 6.5 and 5.4), the ultimate load was not reached during loading tests on composite ground containing expansion steel pipe piles, however after the initial stage of subsidence the bearing capacity of the composite ground was almost equal to the sum of the bearing capacity of the piles and the bearing capacity of the ground.

     3) From the results of the 3D FEM analysis, which used the loading tests at the artificial site as a base model, it became clear that the effect of expansion of the expansion steel pipe piles on the compaction of the surrounding ground was greater for ground with a smaller Young’s modulus (or converted N-value), and that this in turn gave a greater increase in the bearing capacity of the composite ground.

     4) From the above results of the loading tests and FEM analysis, it can be inferred that expansion of the expansion steel pipe piles in composite ground with a converted N-value of approximately 3 or less will lead to an increase in the bearing capacity of the ground.

    DOI: 10.3130/aijs.86.89

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    Other Link: http://id.ndl.go.jp/bib/031234764

  • STUDY ON CHARACTERISTICS OF PILE END BEARING CAPACITY ON THIN BEARING LAYER(PART 1): INVESTIGATION ON FACTORS WHICH INFLUENCE BEARING CAPACITY CHARACTERISTICS BY MODEL PILE TEST

    YAMAZAKI Masahiro

    Journal of Structural and Construction Engineering (Transactions of AIJ)   85 ( 774 )   1035 - 1044   2020

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    Language:Japanese   Publisher:Architectural Institute of Japan  

    The pile end bearing capacity is reduced when the pile is constructed on the thin bearing layer overlying clay layer. For design, it is important to grasp the characteristics of the pile bearing capacity. The characteristic is the relationship between <i>R</i><sub>p</sub> and <i>S</i>. The relationship is expressed by the limit-end-resistance of the pile (<i>R</i><sub>pu</sub>) and relationship between the load ratio (<i>R</i><sub>p</sub>/<i>R</i><sub>pu</sub>) and the settlement ratio (<i>S</i>/0.1<i>d</i>). <i>S</i>, <i>d</i>, <i>R</i><sub>p</sub>, <i>R</i><sub>pu</sub> denotes settlement of pile, pile diameter, pile end load and pile end load at the settlement 0.1<i>d</i>.

     In this study, the characteristics of pile bearing capacity and the factors which influence the characteristics are investigated by model pile tests. The factors are bearing layer thickness, vertical ground pressure, relative density of bearing layer sand and stiffness of clay layer. The bearing layer thickness <i>H</i><sub>s</sub> is 3.0<i>d</i>, 2.0<i>d</i>, 1.5<i>d</i> or infinity which means there is no clay layer. The vertical ground pressure <i>σ</i><sub>v</sub> is 300kPa and 100kPa. The relative density <i>D</i><sub>r</sub> is 90% and 70%. The stiffness of the clay layer varies by selecting the thickness <i>H</i><sub>c</sub> of 0.8<i>d</i> and 0.4<i>d</i>, and selecting clay material of Soft one(SC) and hard one(HC). The characteristics are as follows.

     1) As for <i>R</i><sub>pu</sub> and <i>R</i><sub>p</sub> -<i>S</i> relationship, the smaller the <i>H</i><sub>s</sub> is, the smaller <i>R</i><sub>pu</sub> is. In case <i>H</i><sub>s</sub>=3.0<i>d</i>, the reduction of <i>R</i><sub>pu</sub> is small. Among the tests of <i>H</i><sub>s</sub>=3.0<i>d</i>, when the <i>D</i><sub>r</sub> is higher and the <i>σ</i><sub>v</sub> is lower, the reduction is larger.

     2) In some test results, the phenomenon that the load is reduced where the settlement is increasing is observed. The phenomenon is called the "load reduction" in this paper. It is inferred that some failure occurs in the thin bearing layer when the load reduction is observed. When <i>H</i><sub>s</sub> and stiffness of the clay layer is smaller and the <i>σ</i><sub>v</sub> is higher, the settlement where this phenomenon is observed is smaller.

     3) <i>R</i><sub>pu</sub> is influenced not only by the the stiffness of the clay and <i>H</i><sub>s</sub> but the <i>D</i><sub>r</sub> and <i>σ</i><sub>v</sub> .

     4) Generally, the higher the <i>D</i><sub>r</sub> and <i>σ</i><sub>v</sub> is, the higher the <i>R</i><sub>pu</sub> is. In addition, the smaller the effect of <i>R</i><sub>pu</sub> improvement by <i>D</i><sub>r</sub> is, the smaller the <i>H</i><sub>s</sub> is.

     5) As for the <i>R</i><sub>p</sub>/<i>R</i><sub>pu</sub> -<i>S</i>/0.1<i>d</i> relationship, the smaller the <i>H</i><sub>s</sub> is, the larger the curvature of the relationship curve line is. Unless the settlement reaches the settlement where the load reduction is observed, the curve lines are almost same when the <i>H</i><sub>s</sub> is same.

    DOI: 10.3130/aijs.85.1035

    DOI: 10.3130/aijs.86.77_references_DOI_N8yimpiSkBygPeLx8s5wsYmMlsv

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    Other Link: http://id.ndl.go.jp/bib/030597554

  • 20220 模型杭載荷試験結果に基づく薄層支持層における杭先端支持力の評価法に関する検討 その4 地盤変位と水平土圧に基づくメカニズム

    山崎 雅弘

    構造I   ( 2019 )   439 - 440   2019.7

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  • 20364 模型杭載荷試験結果に基づく薄層支持層における杭先端支持力の評価法に関する検討 その3 パンチングモデルによる評価式の適用性と課題

    山崎 雅弘

    構造I   ( 2018 )   727 - 728   2018.7

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  • 20296 模型杭載荷試験結果に基づく薄層支持層における杭先端支持力の評価法に関する検討 その2 パンチングモデルによる極限支持力の評価法

    山崎 雅弘

    構造I   ( 2017 )   591 - 592   2017.7

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  • 薄層に支持させた杭先端の支持力特性に関する研究(その2)緩い砂地盤における模型杭載荷試験に基づく検討—STUDY ON PILE END BEARING CAPACITY ON THIN BEARING LAYER(PART2)INVESTIGATION BASED ON MODEL TEST OF PILE SETTLED IN DENSE SAND GROUND

    王 博, 山崎 雅弘

    日本建築学会中国支部研究報告集 = Proceedings of annual research meeting, Chugoku Chapter, Architectureal Institute of Japan (AIJ) / 日本建築学会中国支部 編   40   173 - 176   2017.3

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    Language:Japanese   Publisher:日本建築学会中国支部 = Chugoku Chapter, Architectureal Institute of Japan  

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    Other Link: https://www.aij.or.jp/paper/detail.html?productId=601929

  • 薄層に支持させた杭先端の支持力特性に関する研究(その1)締まった砂地盤における模型杭載荷試験に基づく検討—STUDY ON PILE END BEARING CAPACITY ON THIN BEARING LAYER(PART1)INVESTIGATION BASED ON MODEL TEST OF PILE SETTLED IN DENSE SAND GROUND

    王 博, 山崎 雅弘

    日本建築学会中国支部研究報告集 = Proceedings of annual research meeting, Chugoku Chapter, Architectureal Institute of Japan (AIJ) / 日本建築学会中国支部 編   39   381 - 384   2016.3

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    Language:Japanese   Publisher:日本建築学会中国支部 = Chugoku Chapter, Architectureal Institute of Japan  

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    Other Link: https://www.aij.or.jp/paper/detail.html?productId=602312

  • 20228 Bearing Behavior of Vertically Loaded Piles on Bearing Layers : Part4 Additional Study on Experimental Results

    HORII Yoshihiro, NAGAO Toshiaki, YAMAZAKI Masahiro, OGURA Hitoshi

    Summaries of technical papers of annual meeting   ( 2015 )   455 - 456   2015.9

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  • 20229 Investigation on the method of evaluation of Pile End Bearing Capacity on Thin Bearing Layer by Model Test

    YAMAZAKI Masahiro

    Summaries of technical papers of annual meeting   ( 2015 )   457 - 458   2015.9

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  • 模型杭載荷実験による薄層に支持させた杭の先端支持力に関する検討—Investigation on Pile End Bearing Capacity on Thin Bearing Layer by Model Test

    山崎 雅弘

    日本建築学会中国支部研究報告集 = Proceedings of annual research meeting, Chugoku Chapter, Architectureal Institute of Japan (AIJ) / 日本建築学会中国支部 編   38   261 - 264   2015.3

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    Other Link: https://www.aij.or.jp/paper/detail.html?productId=418200

  • 20247 Bearing Behavior of Vertically Loaded Piles on Bearing Layers : Part3 Soil Conditions Unaffected by Lower Layer

    HORII Yoshihiro, YAMAZAKI Masahiro, NAGAO Toshiaki, OGURA Hitoshi, KUWABARA Fumio

    Summaries of technical papers of annual meeting   ( 2013 )   493 - 494   2013.8

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  • 20208 Bearing Behavior of Vertically Loaded Piles on Bearing Layers : Part1 Study on Experimental Results

    HORII Yoshihiro, NAGAO Toshiaki, YAMAZAKI Masahiro, OGURA Hitoshi

    Summaries of technical papers of annual meeting   ( 2012 )   415 - 416   2012.9

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  • 20209 Bearing Behavior of Vertically Loaded Piles on Bearing Layers : Part2 Study on FEM Analysis Results

    YAMAZAKI Masahiro, HORII Yoshihiro

    Summaries of technical papers of annual meeting   ( 2012 )   417 - 418   2012.9

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  • LOAD SETTLEMENT RELATIONSHIPS OF CIRCULAR FOOTING CONSIDERING NEGATIVE DILATANCY CHARACTERISTICS OF LOOSE SAND

    TOMITA Yusuke, YAO Shintaro, MASUI Takeshi, YAMAZAKI Masahiro

    Journal of Structural and Construction Engineering (Transactions of AIJ)   76 ( 661 )   563 - 570   2011

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    Experimental studies on quantitative load-settlement relationship have been well presented, which were carried out with vertically loaded spread foundation on sand ground. However, mechanical properties regarding the relationship have not been theoretically understood. In the previous paper, we elucidated experimentally and theoretically the mechanical properties on dense sand ground. The present study provides the analysis of mechanical properties on loose ground through similar model experiment to the previous one. Under about 15% of the range in a ratio of settlement to the diameter of footing, load-settlement relationship was found to be successfully analyzed through FEM simulation with SMP-Cam-Clay model which was estimable of the negative dilatancy of sand. The FEM simulation reveals that under the range 1.3%, the sand ground under footing exhibits contractile behavior with negative dilatancy, while between 1.3 and 15%, sand behavior undergoes shifts from contraction to contraction and subsidence with slip line directly below edge of footing. Over about 15%, the FEM simulation was apparently not applicable for the analysis of load-settlement relationship and load-settlement relationship shows a good agreement with the subsidence characterized by bearing capacity based on Terzaghi's theory.

    DOI: 10.3130/aijs.76.563

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  • INVESTIGATION ON GROUND EXTENT THAT INFLUENCES LOAD-SETTLEMENT RELATIONSHIP OF PILE END

    YAMAZAKI Masahiro

    Journal of Structural and Construction Engineering (Transactions of AIJ)   75 ( 652 )   1113 - 1120   2010.6

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    To estimate the load-settlement relationship of the pile end, the extent of ground below the end which influences the relationship should be considered. The consideration is more important in case of layered ground. In the paper, the extent is investigated by FEM analysis and pile load test results. On investigation by FEM analysis, 24 models of layered ground and the results show that the extent of the influence is different between two cases of layered ground. In the one case, standard penetration test N-value of a layer is equal to or larger than one of the upper layer. In the other case is opposite. It tells us the point for estimating the bearing capacity that the different average N-value should be adopted between the two cases. And the point is explained by a proposing model that pile end settlement is accumulated compressive deformation of layers. The pile load test result also shows that the point is proper.

    DOI: 10.3130/aijs.75.1113

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  • 杭先端支持力を決める要因の検討--先端付近の上載圧に着目して

    山崎 雅弘, 丸岡 正季

    岡山県技術士会会報 = The bulletin of Professional Engineers of Okayama   7   35 - 40   2010.1

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  • LOAD SETTLEMENT RELATIONSHIPS OF CIRCULAR FOOTING CONSIDERING DILATANCY CHARACTERISTICS OF DENSE SAND

    TOMITA Yusuke, YAO Shintaro, MASUI Takeshi, YAMAZAKI Masahiro

    Journal of Structural and Construction Engineering (Transactions of AIJ)   74 ( 646 )   2263 - 2270   2009

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    Although the quantitative load-settlement relationships of spread foundation have been experimentally well demonstrated on sand ground, the underlying dynamic properties of the relationship remain to be elucidated. Here we present the theoretical properties which were derived from circular footing model experiment and computer simulation. The model experiment was carried out through vertical loading of circular footing dense sand ground in soil tank with different volumes. The quantitative link of load and settlement was analyzed by FEM simulation with SMP-Cam-Clay model which was estimable of sand dilatancy. Comparison of the analytical data with the critical bearing capacity based on Terzaghi's theory lead to the following results: In the soil tank with a large volume and at Terzaghi's critical capacity, sand behavior shifts from continuous to discontinuous, and consequently results in total failure. With regards to a small tank, on the other hand, positive dilatancy exerts a marked binding effect of a soil tank rectangle. Accordingly, the dilatancy causes the increase of mean principal stress and the load exceeds the Terzaghi's critical bearing capacity.

    DOI: 10.3130/aijs.74.2263

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  • 20346 The effect of dilatancy on load-settlement relationships of spread foundation on sand layer : Part 1: Outline of Experiment

    TOMITA Yusuke, YAO Shintaro, MASUI Takeshi, YAMAZAKI Masahiro

    Summaries of technical papers of Annual Meeting Architectural Institute of Japan. B-1, Structures I, Loads, reliability stress analyses foundation structures shell structures, space frames and membrane structures   ( 2008 )   691 - 692   2008.7

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  • 20347 The effect of dilatancy on load-settlement relationships of spread foundation on sand layer : Part 2: Analytical Result

    YAO Shintaro, TOMITA Yusuke, MASUI Takeshi, YAMAZAKI Masahiro

    Summaries of technical papers of Annual Meeting Architectural Institute of Japan. B-1, Structures I, Loads, reliability stress analyses foundation structures shell structures, space frames and membrane structures   ( 2008 )   693 - 694   2008.7

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  • 20355 An estimation by finite element method considering dilatancy in sand about relationships between load and settlement from Loading Test by spread foundation

    TOMITA Yosuke, YAO Shintaro, MASUI Takeshi, YAMAZAKI Masahiro

    Summaries of technical papers of Annual Meeting Architectural Institute of Japan. B-1, Structures I, Loads, reliability stress analyses foundation structures shell structures, space frames and membrane structures   ( 2007 )   709 - 710   2007.7

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  • 20255 Nodular Pile Toe Position in Enlarged Base of Pre-boring and Grouting Method : Study by FEM Analysis Considering Fracture of Enlarged Base

    OGURA Hitoshi, YAMAZAKI Masahiro

    Summaries of technical papers of Annual Meeting Architectural Institute of Japan. B-1, Structures I, Loads, reliability stress analyses foundation structures shell structures, space frames and membrane structures   ( 2006 )   509 - 510   2006.7

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  • METHOD OF SETTING SOIL PARAMETERS OF FEM ANALYSIS TO PREDICT RELATIONSHIP BETWEEN PILE END LOAD AND SETTLEMENT

    YAMAZAKI Masahiro

    Journal of Structural and Construction Engineering (Transactions of AIJ)   70 ( 590 )   55 - 62   2005

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    This paper shows a method of setting soil parameters of FEM analysis in order to predict relationship between pile end load and settlement. The accuracy of the prediction depends on which constitutive equation to be used and the parameter values to be set. Generally it is difficult to set all the parameters properly because the given information is usually only STP N value and overburden pressure. The author proposes to use an approximate constitutive equation to overcome the difficulty and how to set the parameter values. An example is demonstrated in case of bored piles.

    DOI: 10.3130/aijs.70.55_1

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    Other Link: http://id.ndl.go.jp/bib/7332799

  • EARTHQUAKE ENERGY INPUT TO STRUCTURE-PILE-S01L SYSTEMS

    TAKEWAKI Izuru, OHFUCHI Kuniyuki, YAMAZAKI Masahiro

    Journal of Structural and Construction Engineering (Transactions of AIJ)   NO.583 P.39 ( 583 )   39 - 46   2004.9

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    A new frequency-domain method is developed for evaluating the earthquake input energy to a structure-pile-soil system or a super-structure alone subjected to a horizontal ground motion at an outcropping engineering bedrock surface. It is shown that the formulation of the earthquake input energy in the frequency domain is essential for including the frequency-dependent vibration property of the surface ground in terms of the wave propagation theory and the frequency-dependent property of the dynamic Winkler-type spring of the soi l around piles. It is also demonstrated that (l)the present formulation is effective for various input levels and various ground nronerties and (2)the energy input mechanism in the building structure-pile-soil system can be well described by the newly introduced energy transfer function (F-function).

    DOI: 10.3130/aijs.69.39_5

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  • Earthquake energy input to structure-pile-soil systems

    TAKEWAKI Izuru, OHFUCHI K., YAMAZAKI M.

    Jour. of Structural and construction engineering(Transactions of AIJ)   No.583,pp.39-46 ( 2004 )   343 - 344   2004.9

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  • 部材断面寸法をパラメタとした鋼構造立体骨組の最適設計

    日本建築学会構造工学論文集   Vol.50B,pp221-227   2004.3

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  • Optimal design of 3D steel frames Using Cross-Sectional dimensions as Design Parameter

    journal of structural Engineering   Vol.50B, pp.221-227   2004.3

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  • コンクリート材料内の熱水分応力伝達のモデル化

    日本火災学会研究発表会論文集   p78-81   2003

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  • 大口径場所打ちコンクリート杭の鉛直載荷試験とシミュレーション解析

    日本建築学会構造系論文集   第560号,pp115-125   2002.10

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  • 20243 the Equivalent SPT N-Value to Estimate the Bearing Capacity of Bored Pile Toe

    YAMAZAKI Masahiro

    Summaries of technical papers of Annual Meeting Architectural Institute of Japan. B-1, Structures I, Loads, reliability stress analyses foundation structures shell structures, space frames and membrane structures   ( 1 )   485 - 486   2002.8

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  • PILE-TOE LOAD TESTS AND SIMULATION ANALYSIS OF LARGE DIAMETER CAST-IN-PLACE CONCRETE PILES

    Journal of Structural and construction engineering   No.560 ( pp.115-123 )   2002

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  • Influence of Drainage Conditions on Skin Friction of Cohesive Soils Acting on Piles.

    YAMAZAKI Masahiro, NAGAOKA Hiroaki, OKAMOTO Takashi

    Doboku Gakkai Ronbunshu   2001 ( 687 )   309 - 314   2001.9

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    Language:Japanese   Publisher:Japan Society of Civil Engineers  

    Skin friction acting on cast-in-place concrete piles is studied, which go through clayey soil strata to bearing strata. In loading tests, clayey soils deform under undrained condition, on the other hand, under actual structures, when loads are sustained long enough for consolidation, the soil deforms under drained condition. Influence of the different drainage conditions on skin friction is studied by numerical experiments and it is found that influence is not negligible when piles are fairly long, which indicates it necessary to examine further whether it is correct to evaluate skin friction for pile design based only on pile loading test results

    DOI: 10.2208/jscej.2001.687_309

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  • ESTIMATION OF TOE LOAD-SETTLEMENT RELATION OF NON-DISPLACEMENT PILES BASED ON BACK-ANALYSIS OF IN-SITU TESTS

    NAGAOKA Hiroaki, YAMAZAKI Masahiro, ZHANG Ying, OKAMURA Takeshi

    Journal of the Japanese Geotechnical Society   41 ( 1 )   39 - 55   2001.2

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    Language:English   Publisher:The Japanese Geotechnical Society  

    In this paper, a new estimation method is presented for the toe bearing behavior of non-displacement piles embedded into bearing strata of sand. The method is developed by numerical experiments. First, a new in-situ test is proposed whose results can identify five parameters of a bearing stratum uniquely. These are parameters of the stressstrain relations of sand and coefficient of earth pressure at rest. In the in-situ test, a cylinder of, for example, 10 cm in diameter is embedded into the bearing stratum. The measured results are a load-settlement relation at the end of the cylinder and a friction-settlement relation on the surface of the cylinder. These relations are back-analyzed, using elastic-plastic finite element method and neural network, and the parameters are identified. Then using the identified parameters, the toe bearing behavior of a pile is estimated by the elastic-plastic finite element method. The estimation method can be applied to piles embedded into over-consolidated sand as well as normally consolidated sand.

    DOI: 10.3208/sandf.41.39

    DOI: 10.3208/sandf.50.877_references_DOI_UHJ9RQszhAVugMyEDOyAZPVPVjI

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    Other Link: http://dl.ndl.go.jp/info:ndljp/pid/10423697

  • INFLUENCE OF DRAINAGE CONFITIONS ON SKIN FRICTION OF COHESIVE SOILS ACTING ON PILES

    JOURNAL OF GEOTECHNICAL ENGINEERING   Vol.687 ( No.56/pp.309-314 )   2001

  • ESTIMATION METHOD FOR TOE BEARING BEHAVIOR OF LARGE DIAMETER PILE

    NAGAOKA Hiroaki, YAMAZAKI Masahiro, OKAMURA Tsuyoshi, OKAMOTO Takashi

    Journal of Structural Engineering   47B ( 47 )   391 - 400   2001

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    Language:Japanese   Publisher:Architectural Institute of Japan  

    A new estimation method is proposed for toe bearing behavior of a non-displacement pile of large diameter, such as a cast-in-place concrete pile. In the method, first a loading test of a steel pipe of small diameter is carried out whose toe is embedded to a sandy bearing stratum and load-settlement relation at the pipe toe is measured. The relation is back-analyzed and three ground parameters are identified. Using the identified parameters, load-settlement relation at a toe of a non-displacement pile is calculated by finite element method.

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  • SELECTION OF EFFECTIVE INPUT DATA ON IN-SITU TEST LOAD-DISPLACEMENT RELATION TO IDENTIFY GROUND PARAMETERS

    YAMAZAKI Masahiro

    Journal of Structural Engineering   47B ( 47 )   381 - 390   2001

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    Language:Japanese   Publisher:Architectural Institute of Japan  

    This paper proposed a method to predict if the ground parameters can be identified by the in-situ test load-displacement relation, and to select the effective input data on the load-displacement relation for the identification. The method is consists of the two conditions. The one is to check if the dimension number of the load-displacement relation is larger than the one of the parameters by principal component analysis. The others is to check if the all parameters have the principal component which have large influence by correlation coefficient

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  • 小口径鋼管載荷試験による地盤パラメータ同定と大口径杭先端荷重〜沈下量関係の評価

    日本建築学会構造工学論文集   47B   391 - 400   2001

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  • 地盤パラメータ同定のための原位置試験荷重形関係の有効な入力値の選定

    日本建築学会構造工学論文集   47B   381 - 390   2001

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  • Scale effects on Bearing Behaviors of Non-displacement pile

    B-1   2000

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  • 大口径場所打ちコンクリート杭の先端支持力における寸法効果

    日本建築学会大会学術講演梗概集   B-1   2000

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  • Estimation of Toe Load-Settlement Relation of Non-Displacement Piles Based on Back-Analysis of In-Situ Test

    Soils and Foundations   39 ( 2 )   119 - 130   1999

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  • 小口径杭載荷実験結果による大口径杭の先端支持力の推定(『地盤工学会論文報告集』Vol.39,No.2 (1999年4月発行)掲載論文の概要)

    長岡 弘明, 山崎 雅弘

    土と基礎   47 ( 5 )   65 - 66   1999

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    Language:Japanese   Publisher:土質工学会  

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  • Toe Bearing Behauiors of Large Diameten Piles Estimated by Loading Tests of Small Diameten Piles

    HIROAKI NAGAOKA, MASAHIRO YAMAZAK

    Soils and Foundations   39 ( 2 )   119 - 130   1999

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    Language:English   Publisher:The Japanese Geotechnical Society  

    A method to estimate the load-settlement relation at the toe of a large diameter pile is presented. Input information is the load-settlement relation of the toe of a small diameter pile obtained by loading test. First, soil parameters and coefficient of earth pressure at rest are determined as a set of plural solutions by back analysis, using finite element method of elastic-plastic soil and genetic algorithm. Since the input information is the load-settlement relation alone, soil parameters and so on can not be determined uniquely. Using the sets, finite element analyses are carried out which calculate load-settlement relations at the toe of a large diameter pile. Since the sets are plural, plural relations are obtained which determine the possible region of the relation. If a loading test for the large diameter pile is carried out, the load-settlement relation at the toe of the pile will coincide with one of the relations in the region. The load test results of large and small diameter concrete blocks which were constructed beneath the pile toes are analyzed. Using the tests result from the small diameter block, the possible region of the relation of the large diameter block is estimated and it is confirmed that the test results of the large diameter block is within the estimated region and the method is effective.

    DOI: 10.3208/sandf.39.2_119

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    Other Link: http://id.ndl.go.jp/bib/4709403

  • 静止土圧係数と地盤パラメータ同定のための原位置試験その1.同定可能な原位置試験の決定方法 その2.同定可能な原位置試験の確定と杭先端支持力評価への適用例

    第34回地盤工学研究発表会 発表講演集   2   1405 - 1408   1999

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  • Identification of coefficient of earth presence at rest and soil parameters ley in -situ test

    2   1405 - 1408   1999

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  • 土質桂状図情報を用いた埋込み杭の先端荷重~沈下量関係の評価(『地盤工学会論文報告集』Vol.38,No.2(1998年6月発行)掲載論文の概要)

    長岡 弘明, 山崎 雅弘

    土と基礎   46 ( 7 )   68 - 68   1998

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    Language:Japanese   Publisher:土質工学会  

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  • Estimation of Relations between Point Bearing Loads and Settlements of Bored Precast Piles Using Soil Boring Log Informations

    HIROAKI NAGAOKA, MASAHIRO YAMAZAKI

    Soils and Foundations   38 ( 2 )   101 - 113   1998

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    Language:English   Publisher:The Japanese Geotechnical Society  

    A new estimation method is proposed for the relationship of the point bearing loads and point settlements of bored precast piles installed in sandy supporting strata by preboring or inner excavation. The method is derived using analyses by finite element method, back-analyses by neural network and regression analyses. The piles have widened holes at the pile points which are filled with cement milk. Nomographs are prepred and, if the diameter of the widened part, embedded length of the part into the supporting stratum, N-value and effective overburden pressure on the surface of the stratum are given, we can estimate the relations by manual calculation.

    DOI: 10.3208/sandf.38.2_101

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    Other Link: http://dl.ndl.go.jp/info:ndljp/pid/10423353

  • Equivalent SPT N-value for Estimating Point Bearing Capacity of Pile

    1998

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  • 抗先端支持力評価のための等価N値

    山崎雅弘

    日本建築学会大会学術講演梗概集   1998

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  • Bearing Mechanism of a Widened Part Filled with Cement Mortar at the End of a Bored Precast Pile

    YAMAZAKI Masahiro, NAGAOKA Hiroaki

    Journal of Structural and Construction Engineering   62 ( 491 )   73 - 80   1997

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    Language:Japanese   Publisher:Architectural Institute of Japan  

    A tip is defined here as mortar filled at a pile point of a prestressed concrete pile. New bearing mechanism of the tip are revealed through a series of finite element analyses modeling a tip, ground and a pile. Influence of shape of a tip bottom as well as adhesion between the tip and the pile on point bearing capacity are discussed. It is recommended that shape of the tip bottom should be cone-like and the adhesion should be so high that there is no slip between the tip and the pile.

    DOI: 10.3130/aijs.62.73_1

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    Other Link: http://id.ndl.go.jp/bib/4118003

  • Optimum Solution in Labor Resource Leuelling Problems Using Genetic Algorithms

    Journal of Architeeture, Planning and Environmental Eugineering   ( 491 )   183 - 187   1997

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  • BEARING MECHANISM OF A WIDENED PART FILLED WITH CEMENT MORTAR AT THE END OF A BORED PRECAST PILE

    YAMAZAKI Masahiro, NAGAOKA Hiroaki

    Journal of Structural and Construction Engineering (Transactions of AIJ)   62 ( 491 )   73 - 80   1997

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    Language:Japanese   Publisher:Architectural Institute of Japan  

    A tip is defined here as mortar filled at a pile point of a prestressed concrete pile. New bearing mechanism of the tip are revealed through a series of finite element analyses modeling a tip, ground and a pile. Influence of shape of a tip bottom as well as adhesion between the tip and the pile on point bearing capacity are discussed. It is recommended that shape of the tip bottom should be cone-like and the adhesion should be so high that there is no slip between the tip and the pile.

    DOI: 10.3130/aijs.62.73_1

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    Other Link: http://id.ndl.go.jp/bib/4118003

  • 建築工事における労務平準化への遺伝的アルゴリズムの適用

    日本建築学会計画系論文集   ( 491 )   183 - 187   1997

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  • 埋込み杭, 場所打ちコンクリート杭の先端地盤支持力及び先端部構造耐力

    山崎雅弘

    京都大学博士論文   ( 1997 )   82   1996

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    Language:Japanese   Publisher:日本建築学会  

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  • EFFECT OF UNDERREAMED END SHAPES ON THE STRUCTURAL STRENGTH OF CAST-IN-PLACE CONCRETE PILE ENDS

    YAMAZAKI Masahiro, NAGAOKA Hiroaki, NAKAMURA Tsuneyoshi

    Journal of Structural and Construction Engineering (Transactions of AIJ)   60 ( 470 )   95 - 103   1995

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    Language:Japanese   Publisher:Architectural Institute of Japan  

    Finite element analysis is carried out.in order to evaluate the structural strength of the underreamed end of cast-in- place concrete piles, expressing ground and concrete as elastic-plastic bodies. New failure mechanism is found, where tensile stresses in radial and circumferential direction reduces the structural strength of the end and the failure of the end occurs before ground failure. New end shapes are proposed which prevent the mechanism and enhance the structural strength.

    DOI: 10.3130/aijs.60.95_1

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    Other Link: http://www.aij.or.jp/paper/detail.html?productId=178100

  • Dependence of tip strength of a prestressed concrete pile on its shape

    Journal of Structural Engineering   ( 41B )   467 - 476   1995

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  • 既製コンクリート杭根固め部構造耐力の施工形状依存性

    山崎雅弘

    構造工学論文集   41 ( 41B )   467 - 476   1995

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  • Effect of Undreamed End Shapes on the Structural Strength of Cast-in-place Concrete Pile Ends

    YAMAZAKI Masahiro, NAGAOKA Hiroaki, NAKAMURA Tsuneyoshi

    JOURNAL OF STRUCTURAL AND CONSTRUCTION ENGINEERING   60 ( 470 )   95 - 103   1995

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    Language:Japanese   Publisher:Architectural Institute of Japan  

    Finite element analysis is carried out.in order to evaluate the structural strength of the underreamed end of cast-in- place concrete piles, expressing ground and concrete as elastic-plastic bodies. New failure mechanism is found, where tensile stresses in radial and circumferential direction reduces the structural strength of the end and the failure of the end occurs before ground failure. New end shapes are proposed which prevent the mechanism and enhance the structural strength.

    DOI: 10.3130/aijs.60.95_1

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    Other Link: http://www.aij.or.jp/paper/detail.html?productId=178100

  • 大規模膜構法の研究(その3)耐震設計

    日本建築学会大会学術講演梗概集   1990

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  • A study of Large-Scale Membrane Structure Supported by Steel Space Frame PART 3 Seismic Design

    Summaries of Technical Papers of Annual Meetings Architectural Institute of Japan   1990

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  • CGを利用したケーブル補強膜・骨組み構造設計システム

    情報システム利用シンポジウム   1989

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  • Structural Design System for Membrane String Structure incorporating the Computer Graphics

    Proceedings of the 12th Symposium on Computer Technology of Information, System and Applications   1989

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Awards

  • 日本建築学会 奨励賞

    1998  

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    Country:Japan

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Research Projects

  • Investigation of the mechanism of spalling of high-strength concrete during fire considering heat, moisture and stress transfer

    Grant number:23656350  2011 - 2013

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Exploratory Research

    HARADA Kazunori, NISHIYAMA Minehiro, YAMAZAKI Masahiro, KWON Young Jin

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    Grant amount:\3900000 ( Direct Cost: \3000000 、 Indirect Cost:\900000 )

    In this study, a hypothesis was adopted that the thermal spalling will take place under the effect of pore pressure rise and thermal stress. Pore pressure is created by the evaporation of moisture, while the thermal stress is created by non-uniform temperature profile. To verify the hypothesis, experiments were carried out. Ring compression test is to compress cylinder specimen only at the perimeter region. The compression stress is to simulate the thermal stress during early stage of heating. Fire resistance test is to heat the cylinders and prism rapidly. From the experiments, it was concluded that the spalling takes place where temperature gradient is large. The effect of pore pressure is marginal, because the spalling could take place even after the specimen is cracked. In connection with experiments, numerical simulations on heat conduction and stress distribution were carried out. The results showed the tendency of concentration of thermal stress to the region of spalling.

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  • Frequency-domain method for evaluation of earthquake input energy to building structure-soil systems

    Grant number:16560496  2004 - 2005

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    TAKEWAKI Izuru, YAMAZAKI Masahiro, KANNO Yoshihiro

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    Grant amount:\3600000 ( Direct Cost: \3600000 )

    The purpose of this project is to develop a new frequency-domain method for evaluation of earthquake input energy to structure-soil systems (or structure-pile-soil systems) in order to develop more reliable earthquake-resistant design methods for building structures. The following results have been obtained in this project.
    1. A new critical excitation method is developed for soil-structure interaction (SSI) systems. The input energy expression can be of a compact form via the frequency integration of the product between the input component (Fourier amplitude spectrum) and the structural model component (so-called energy transfer function). With the help of this compact form, it is shown that the formulation of earthquake input energy in the frequency domain is essential for solving the critical excitation problem and deriving a bound on the earthquake input energy for a class of ground motions. The energy dissipated in structures and ground (or radiated into ground) can be captured appropriately with the present formulation.
    2. Exact higher-order sensitivities of the input energy to the SSI system are derived with respect to uncertain soil stiffness and damping parameters by taking full advantage of the frequency-domain method. The exact higher-order sensitivities facilitate to express the input energy variation due to uncertainty of ground stiffness and damping and to find the most unfavorable combination of the uncertain parameters leading to the maximum energy input.
    3. The earthquake energy input rate is treated as a new measure of criticality. The key for finding the new random critical excitation is the interchange of the order of the double maximization procedures with respect to time and to the PSD function. Extension of the proposed method is discussed to a more general ground motion model, i.e. non-uniformly modulated non-stationary models, and to a more general problem for variable envelope functions and variable frequency contents.

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  • Management Support System for Concurrent Building Projects in Design and Construction

    Grant number:07405054  1995 - 1997

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    NAGAOKA Hiroaki, KANETA Takashi, YAMAZAKI Masahiro, FURUSAKA Shuzo

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    Grant amount:\3700000 ( Direct Cost: \3700000 )

    This research consists of three parts. In the first part, activities included in building construction process of a standard project were dehined and structured with its reachability matrix, which was led by an adjacency matrix using the relationships among activities. As a result, building construction process was expressed by process models of categories, such as shedule control, cost control, building system design, and so on. These models can clarify how the activities interact one another.Effectiveness of the model was then discussed as tools of concurrent engineering. The second part presented an overall approach to the integration of design and construction in building construction projects. Its approach relies on the information technologh to support members of design and construction teams throughout the project's life cycle. To manage the information correctly in execution of jobs, all the items to be considered in view of project management were covered. Character of the supporting tools was discussed around integrated object oriented model. As the primary tool, process model was described with its prototype using Object Pascal. The third part described integrated modeling of information required in a concurrent building construction progect. The object-oriented datta base (OODB) was introduced to enable collaborated design, reuseability along the project's process, and flexibility to alterations. This model was supported by using relationship, inheritance relationship and visibility of OODB.It can offer multiple windows by using relationship, deal with vague information to be handed down to later process by inheritance relationship and visibility. The effect of alterations can be estimated by visibility. Its prototype managing multidisciplinary jobs in conceptual was developed.

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  • Construction Technology and Information Transfer to Small Design Offices and Small Contractors

    Grant number:07455240  1995 - 1997

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    FURUSAKA Shuzo, KANETA Takashi, YAMAZAKI Masahiro, NAGAOKA Hiroaki

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    Grant amount:\6500000 ( Direct Cost: \6500000 )

    The paper discusses the problems relating to construction technology and Information transfer to small design offices and small contractors, particularly new methods on management of construction projects. The paper mainly includes four parts. In Part 1, we discuss principles of value management (VM), and then present multi-stage VM approach at the design stage. Applying the VM approach to the real construction project, we verify the VM approach is effective. In Part2, we deal with the cost estimating system in a design firm. At first, we survey cost estimating process, and clarify that decided specifications are not fully utilized. Then we show that, if we utilized the decided specifications completely and also uticlzed default values given by the design firm, estimated costs of a structural work and finishing work are very effective for adjusting of construction cost. Based on those findings, we proposed a new method for adjusting and convergings construction cost using hierarchy neural network. In Part 3, we clarify the process of making and approve of shop drawings, and develop collaborative working system among a client, architects, engineers, contractors, and parts makers that makes them to continue to pursuing optimum detail design and construction method during construction term. In Part 4, we survey the state of arts of precast concrete panel (PC) construction method, and clarify the reason of not so wide distribution of PC method. And then using metagames theory, we analyze the conflict between a client, architects, and contractor relating to PC method.

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  • A study on the design of piles

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    Grant type:Competitive

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  • A study on bearing mechanism of piles

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    Grant type:Competitive

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  • FEM解析による基礎構造の挙動推定法の適用

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    Grant type:Competitive

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  • 杭基礎の設計に関する研究

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    Grant type:Competitive

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  • 杭基礎の支持力機構に関する研究

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    Grant type:Competitive

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