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Article type: Cover
1991Volume 428 Pages
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Published: October 30, 1991
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Article type: Cover
1991Volume 428 Pages
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Published: October 30, 1991
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Article type: Index
1991Volume 428 Pages
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Article type: Appendix
1991Volume 428 Pages
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Published: October 30, 1991
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Article type: Appendix
1991Volume 428 Pages
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Toshio FUKUSHIMA
Article type: Article
1991Volume 428 Pages
1-15
Published: October 30, 1991
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Neutralization processes of concrete are theoreticall modelled for three assumed cases of neutralization mechansims and discussed based upon unsteady state dynamic analysis for the unsteady, diffusion of carbon dioxide in concrete accompanied by carbonation reaction with calcium hydroxide and calcium silicate hydrate, taking into accout of both cases of the constant and increasing concentration of atmospheric carbon dioxide. Influences of various extrinic and intrinsic factors on the progress of the neutralization of concrete are evaluated, using the parabolic law involving constant term derived from this usnsteady state dynamics, which is effective enough to understand and predict almost all the neutralization' processes.
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Rinji KANEKO, Sakichi OHGISHI
Article type: Article
1991Volume 428 Pages
17-24
Published: October 30, 1991
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Experimental investigations on flexural fatigue strength and crack growth in plain concrete beam with notch or unnotch were conducted by means of four-points bending test method. These tests were carried out under the following condition, a) size of concrete beam ; 75×75×300 mm, b) single edge notch beam with relative notch depth ; 0.12 constant, c) cyclic load at 5 Hz, d) repeated maximum load rates ; 0.8, 0.75, 0.7 and 0.65, e) load amplitude ; 0.1, 0.25, 0.5 and 0.75. According to test results, the conclusions were obtained as follows ; 1) flexural fatigue strength in notched beam can be explained by equation of S_<max>=0.839-0.052・logN_f, 2) flexural fatigue strength of notched beam is about 10 % smaller than one of the unnotched beam, 3) in range of strain softening zone, Paris' low can be applied for concrete, 4) material constant, m in Paris' low showed by (da/dN)=C(Δk)^m, is 4.2〜4.9 for concrete.
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Tomozo SOSHIRODA, Yoshitsugu NOZAKI, Koichi KOBAYASHI
Article type: Article
1991Volume 428 Pages
25-33
Published: October 30, 1991
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Full scale model structures with several mixes of concrete were used to study estimation of strength of concrete in structures by non-destructive testing. Estimation equations by rebound number method, pulse velocity method and combined method of reboud number and velocity were propsed. Furthermore, supplement of parameters by the water cement ratio of concrete to equations decreased in estimation error. Ranges of dispersion of estimations, represented by two times of the standard deviation were apprpximately as follows : 80 kgf/cm^2 for rebound number method, 120 kgf/cm^2 for pulse velocity method, 74 kgf/cm^2 for combined method and 53 kgf/cm^2 for combined method with water cement ratio as an additional parameter.
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Kuniyuki TOMATSURI
Article type: Article
1991Volume 428 Pages
35-46
Published: October 30, 1991
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Strength distribution of high strength concrete were investigated on 14 mix design concretes of 3 construction projects. It was cleared that standard deviation is not constant but varys closely in accordance with strength gain. The prediction method of relatively long term strength deviation through standard deviation at 28th day and strength gain ratio was proposed and examined. Its effectiveness was vavified.
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Kyoji TANAKA, Byung-chang SONG, Michio KOIKE
Article type: Article
1991Volume 428 Pages
47-53
Published: October 30, 1991
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This paper deals with the ozone degradation of rubber sheet for roof covering under fluctuating concentration. The ozone degradation under constant concentration can be expressed by the following equation. t=10^B/X^A ∴ X^A・t=10^B, where t=time to failure, cracking or rupturing, hrs X=ozone concentration, pphm A,B=material constants. The effect of fluctuation ozone concentration may be expressed by the integration of ozone concentration with time. The material constants, A and B were determined by the test under constant ozone concentration. Then the test under fluctuating concentration, following sine curves. Comparing both results obtained by the test and calculation, It is concluded that the effect of fluctuating ozone concentration can be estimated by the integration of ozone concentration with time.
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Toshinori MURAKAMI, Kiyoshi MASUO
Article type: Article
1991Volume 428 Pages
55-67
Published: October 30, 1991
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The reinforcing method with diagonal reinforcements in multi-directions for circular R/C columns were proposed by the authors. The proposed reinforcing method for these columns [MXRC] is composed of the spiral hoops having a superior ductility for high axial load and the diagonal reinforcements having a superior strength for lateral load. To investigate the confinement effectiveness of the spiral hoops, seismic loading tests were conducted. In this test, six test units were tested, and the variable investigated were the amount of the spiral hoops and axial load. Experimental and analytical results are as follows. 1) Ultimate shear strength of MXRC with enough spiral hoops increase by the confinement effectiveness rather than them with a little spiral hoops. 2) Ultimate shear strength calculated by the superposition strength theory gives fairly good agreement with the experimental tesult.
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Noboru SAKAGUCHI
Article type: Article
1991Volume 428 Pages
69-78
Published: October 30, 1991
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A new type of frame structure composed of steel beams and reinforced concrete columns is proposed. The concrete in the beam-column connection is confined by thin steel plates called "cover plate". Shear capacity of connectionis investigated experimentally. Thirteen specimens of interior column-beam assemblage and four specimens of exterior column-beam assemblage were tested. The shear forces acting in the connection are resisted by the steel web panel and the concrete panel and the cover plates. The effective length of the steel web and the cover plates were determined from test results. An equation of the effective width of the concrete panel in the connection is proposed.
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Tatsuo MOGAMI, Takeyosi KORENAGA
Article type: Article
1991Volume 428 Pages
79-88
Published: October 30, 1991
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A parametric analysis on load-deformation relationship of unbonded prestressed concrete beams, which had varied sections and were subjected to antisymmetric moment distributions, was carried out. The method of the analysis was the same one described in part 1 of this paper. The main parameters were prestressing and reinforcing steel ratio, shear-span ratio, and the compressive strength of concrete. As a results, it was confirmed that q_0 (= P_0/bDσ_B) is an essential value to characterize the structural behavior of unbonded prestressed concrete beams, and a method for predicting the load-deformation relationship of unbonded prestressed concrete beams subjected to antisymmetric moment distributions is presented.
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Hideyuki TAKASHIMA, Shiro KATO
Article type: Article
1991Volume 428 Pages
89-95
Published: October 30, 1991
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The present investigation deals with the effects of initial imperfections on the ultimate strength of a single layered reticular dome whose connections are semi-rigidly jointed. The initial imperfections are an initial deflection and an additional concentrated load at the single nodal point of the dome. Elastic and elasto-plastic buckling analyses are executed with respect to several parameters which define the magnitudes of imperfections. These results from the calculations are summerized by a classical buckling load of isotropic shell which is equivalent to the framed dome. From the results some conclusions about the effects of adoped imperfections are drawn.
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Shiro KATO, Seishi YAMADA, Hideyuki TAKASHIMA, Ryoichi SHIBATA
Article type: Article
1991Volume 428 Pages
97-105
Published: October 30, 1991
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The target of the present study is to investigate the buckling stress of a member representative of a rigidly jointed single-layer reticular dome. The buckling stress and the normalized slenderness ratio have been derived from elastic plastic buckling analysis and the elastic buckling stress by linear eigenvalue analysis, respectively. The results of the elastic plastic buckling analyses are summarized to evaluate the ultimate strength of the reticular dome as a function of the normalized slenderness ratio. According to several numerical analyses, it is confirmed that the proposed design procedure gives an accurate estimation on the buckling collapse of reticular domes.
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Tadahiro FUKUSUMI, Kaoru KUSAKABE, Hisashi NOZOE, Yoshihisa GYOTEN
Article type: Article
1991Volume 428 Pages
107-117
Published: October 30, 1991
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Cylindrical shells are used in ocean space as resevoirs and floats to support platforms and buildings. Dynamic response characteristics of large scaled floating type of elastic cylindrical structure has not yet been clarified. In this paper, a cylindrical shell strucuture which consists of an elastic shell wall, bottom plate and mooring springs on its circumference is studied, and not only motion as a whole sturcture but also distribution of stresses and displacements of the elastic plate and shell are investigated from the elastic structural point of view. Solutions of motion of the elastic structure system and the fluid are obtained as theoretical solution consistently. Dynamic responses of the structure and the fluid to the harmonic water wave are determined and the effect of the thickness of the shell and plate and the stiffness of the mooring spring on the responses are described.
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Yasuo FUJISAWA, Koichi MASUDA, Hisaaki MAEDA
Article type: Article
1991Volume 428 Pages
119-130
Published: October 30, 1991
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The authors developed a computer program by using three dimensional source distribution method considering the forward speed based on linear potential theory. The authors conducted model experiments on a cone typed structure during towing and non-towing conditions and compared calculated results with experimental results regarding hydrodynamic forces, wave exciting forces and the effects of forward speed and clarified the characteristics of these results. The calculated results and experimental results with a constant forward speed in waves are shown a good correlation within the linear potential theory.
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Article type: Appendix
1991Volume 428 Pages
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Published: October 30, 1991
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Article type: Cover
1991Volume 428 Pages
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Published: October 30, 1991
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