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2001 Volume 66 Issue 544 Pages
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Article type: Cover
2001 Volume 66 Issue 544 Pages
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Article type: Appendix
2001 Volume 66 Issue 544 Pages
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Article type: Appendix
2001 Volume 66 Issue 544 Pages
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Article type: Appendix
2001 Volume 66 Issue 544 Pages
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Article type: Appendix
2001 Volume 66 Issue 544 Pages
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Article type: Appendix
2001 Volume 66 Issue 544 Pages
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Kiyofumi KURUMISAWA, Kyoji TANAKA
Article type: Article
2001 Volume 66 Issue 544 Pages
1-6
Published: June 30, 2001
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To understand the property of concrete, the knowledge about pore structure of hardened cement is important, particularly in early age of a few weeks, because the pore structure change by active hydration. In the paper, the change of pore structure in early age was investigated by observation of pores through gallium intrusion method developed by the authors and EPMA analysis. As the technique is limited to 2-dimensional analysis, the simulation of hydration developed by Bentz was furthermore carried outto obtain 3-dimensional information about pore structure. It was quantitatively made clear that the value of pore and the number of continuous pores rapidly decreased in early age.
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Tokunao OH-OKA, Yoshinori KITSUTAKA, Ken WATANABE
Article type: Article
2001 Volume 66 Issue 544 Pages
7-13
Published: June 30, 2001
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Crack propagation of the short cut fiber reinforced concrete due to drying shrinkage was investigated. Shrinkage crack tests using specimens with external restriction were performed. The relation between tensile stress and crack width of the specimen was measured and this relationship was compared with the tri-linear tension softening diagram. Tri-linear tension softening diagram was approximated to the poly-linear tension softening diagram which was analyzed by the data of a load-load point displacement curve obtain from three-point bending test. Analysis method of crack propagation of the shrinkage crack specimen was proposed based on the crack equation analysis method using a variant tri-linear tension softening diagram according to the concrete age.
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Akihisa KAWAGUCHI, Makoto KANDA, Eizo MARUTA
Article type: Article
2001 Volume 66 Issue 544 Pages
15-22
Published: June 30, 2001
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The Hybrid vibration system, which was presented by Dr. Kanda, is combined a movable mechanical system and a personal computer for the evaluation of wind forces on a vibrating scale model in wind tunnel tests. The computer has to calculate the next position of a scale model against present wind forces and instruct motors, instantaneously. Then, this paper shows that the response delay and the effects of the inertia force of a scale model were compensated for the new hybrid vibration system. Especially, the hybrid vibration system is characterized to adopt the mass inertia factor in the analytical procedure. Also, the results obtained by the hybrid vibration tests are good agreement with traditional tests. Further the hybrid system was completely able to capture the wind forces on the vibrating scale model, while traditional techniques were unable to.
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Naohiro NAKAMURA
Article type: Article
2001 Volume 66 Issue 544 Pages
23-29
Published: June 30, 2001
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It is important to estimate the influence of the layered soil in soil-structure interaction analysis. Although great numbers of investigation were presented on this subject, practical methods without complex calcuration are very few. In this paper, a simple and practical method to estimate the horizontal impedance of the rigid foundation on the surface of multi-layered soil is proposed. By this method, the time domain impedance function is calculated directly and easily with good accuracy. The efficiency of the time history response analysis of this method is also confirmed.
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Kenichiro NAGATO, Hiroshi KAWASE
Article type: Article
2001 Volume 66 Issue 544 Pages
31-37
Published: June 30, 2001
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In this paper, we try to estimate the actual yield strengths of reinforced concrete (RC) buildings based on the damage statistics in Kobe surveyed after the Hyogo-ken Nanbu earthquake of 1995 and nonlinear response analyses for synthetic waveforms simulated by Matsushima et al. (2000). First, we construct a set of building models that represents the RC building stock in Kobe and we create a plausible nonlinear multi-degrees-of-freedom models for four different heights of buildings based on the current code and practice. We must assume the damage criterion and the strength distribution a priori. When we calculate the damage ratios for these standard models we find that they are so high that we must increase the average yield strengths in order to match the calculated damage ratios to the observed. The estimated average yield strengths are much higher than those based on the code, especially for low-rise buildings. Using this set of building models we succeed to reproduce the belt-shaped area with high damage ratios in Kobe.
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Susumu OHNO, Katsuya TAKAHASHI, Masato MOTOSAKA
Article type: Article
2001 Volume 66 Issue 544 Pages
39-46
Published: June 30, 2001
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Attenuation relations of peak ground acceleration, peak ground velocity, and acceleration response spectrum in both horizontal and vertical components are estimated by regression analyses of California strong-motion data set, which contains many near-source records of shallow inland earthquakes. These attenuation relations can take into account the effects of fault extension, reflection from Moho, and nonlinear amplification of holocene stratum. By comparing with Japan inland earthquake data, it is confirmed that these attenuation relations are applicable to the estimation of strong motions on pre-Quaternary and Pleistocene strata for Japan inland earthquakes. However, in the estimation on Holocene stratum the applicability are decreased because area-dependent variations of soil amplification are large.
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Ritsuko ISHIKAWA, Hitoshi SUWA, Matsutaro SEKI
Article type: Article
2001 Volume 66 Issue 544 Pages
47-52
Published: June 30, 2001
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This report describes a process of modeling for non-linear visco-elastic damper. The visco-elastic damper is effective under both wind and earthquake loading, although it's dynamic characteristics depend on temperature, strain and vibration frequency. The authors evaluated these characteristics quantitatively from dynamic and static loading tests using a full-scale device, and proposed an analytical model that takes into account strain and frequency dependence. The analytical model is a three elements model composed by non-linear spring elements and constant damping element. The modified bi-linear model is introduced as non-linear hysteretic model of the spring elements.
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Fuming ZHANG
Article type: Article
2001 Volume 66 Issue 544 Pages
53-60
Published: June 30, 2001
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Rocking Center Designated (RCD) Mechanism is proposed as a tool to control the vibration modes of structures. An ideal RCD mechanism is simply a rigid body guided on a sphere surface, and the rocking center of the rigid body is decided and designated by the curvature of the sphere surface. And the RCD mechanism can also be realized by replacing vertical columns in soft story structure by diagonal columns that pointed to the rocking center. If the RCD mechanism is incorporated into a structure, the vibration modes of the structure can be designated and the input of motions at a specific position can be controlled. In this paper, RCD mechanism and its effectiveness in structure control are explained. Structure using the concept of RCD mechanism is expected to be a new strategy for eliminating damage of civil structures during intense earthquakes.
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Naohito ADACHI, Tomonori IKEURA, Shoji UCHIYAMA, Tomiichi UETAKE, Masa ...
Article type: Article
2001 Volume 66 Issue 544 Pages
61-67
Published: June 30, 2001
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The objective of this study is to clarify the effects of installation condition of seismometers on strong motion records. Simultaneous observation of strong motions is conducted using differently installed seismometers(K'NET type and borehole type). Furthermore spectral characteristics of strong motion records are simulated by an axisymmetric FEM. As the results, spectral characteristics of K-NET type and borehole type are almost similar in the whole frequency range for vertical component and in the frequency range up to about 10Hz for horizontal components. While in the frequencies higher than 10Hz, spectral amplitudes of K-NET type are larger than those of borehole type due to the effects of seismometer base.
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Akihiko UCHIDA, Munenori HATANAKA, Kohji TOKIMATSU
Article type: Article
2001 Volume 66 Issue 544 Pages
69-75
Published: June 30, 2001
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This paper presents a plenty of modeling results on the cyclic deformation characteristics of natural soil samples obtained from laboratory tests by RO and HD models. The G〜γ and h〜γ curves simulated by RO and HD models were compared with cyclic deformation test results for the natural soil samples. The G〜γ curve simulated by the HD model is better corresponds to the test results than that of the RO model at a large strain level. The h〜γ curves simulated by the HD model well agree with the test results. A simplified evaluation method of the modeling constants for HD model was described in order to estimate the cyclic deformation characteristics for natural soils without laboratory tests. The modeling constants for HD model, τ_<max> and h_<max> can be determined from the confining pressure, in-situ shear wave velocity and sand contents. By using the method proposed here for the determination of HD model constants, the equivalent G〜γ, h〜γ relations for natural soils can be well estimated by the HD model.
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Mamoru SAHARA, Noriyuki AKINO, Koji TOMINAGA
Article type: Article
2001 Volume 66 Issue 544 Pages
77-84
Published: June 30, 2001
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In a high-rise building and a low-rise building having a common basement supported by friction piles, differential settlements may occur. It is possible to reduce the differential settlements by varying the length of piles under the high-rise and low-rise buildings. The long-term measurements of the differential settlements are made in the buildings under which the piles were designed on the basis of such a conception. This paper presents the measured results of the settlements in the buildings and the axial forces from strain gages installed in the piles. Furthermore, the measured settlements and axial forces are compared with the results calculated by the non-linear finite element method, which has been proposed by one of the authors.
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Yasunari ASHIDA, Nobumi HAYASHI, Makoto TAKAYAMA
Article type: Article
2001 Volume 66 Issue 544 Pages
85-91
Published: June 30, 2001
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The paper presents the results of failure experiments and an elasto-plastic analysis of free-formed shells. The shapes of free-formed shells were obtained by numerical form finding process. The six models with different tie-beam stiffness and different rises were tested, and the results of some of them were compared with analytical results. These analytical results show the good agreement with the test results. And these results indicate that the stiffness of the free-formed reinforced concrete shells are considerably affected by the support condition and rise-span ratio, but the effects of these factors are not clear in the load carrying capacity of the shells.
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Kozo TSUMURA, Manabu YOSHIMURA
Article type: Article
2001 Volume 66 Issue 544 Pages
93-100
Published: June 30, 2001
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Bilateral and unilateral loading tests were conducted to study general nature of shear-failing reinforced concrete columns under multi-axial loading conditions. Various kinds of loading paths were employed for the bilateral loading tests, and various values of axial load were applied for the unilateral loading tests. Through the tests, the following points have been revealed: 1) the failure surface for bilateral loads can be represented by a circle irrespective of loading paths, 2) the failure surface for tri-axial loads can be represented by an ellipsoid, and 3) the observed behavior after maximum lateral loads can be explained by using the concepts of the reduced failure surface and associated flow rule.
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Hiroshi HOSOYA, Yoshinobu ASANO, Yoshio OGAWA, Hiroshi IMAI
Article type: Article
2001 Volume 66 Issue 544 Pages
101-108
Published: June 30, 2001
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To develop a construction method of reinforced concrete column using precast concrete shell which functions as the form and part of the column member, monotonous tension loading tests of main reinforcement and horizontal cyclic loading tests of column members using precast concrete shell were carried out. Bond splitting strength of main reinforcement was examined, and the result is discussed. An equation for bond splitting strength that is based on the Design Guidelines for Earthquake Resistant Reinforced Concrete Buildings of A. I. J. is proposed. The precision of calculated values of the equation of bond splitting strength is verified by comparison with test values.
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Yoshio KANEKO, Hirozo MIHASHI
Article type: Article
2001 Volume 66 Issue 544 Pages
109-116
Published: June 30, 2001
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The objective of this paper is to examine the performance of constitutive models for describing the cracking behavior and the load-displacement characteristics of shear failure of concrete structures. Concrete simple deep beams in different shear-span ratios (0.5 to 2.0) were analyzed. In addition, in order to expand the comprehension on the effect of constitutive model parameters in the deep beams to slender beams, the beams in the shear-span ratio of 4.0 were numerically simulated. The structural analysis was carried out by means of nonlinear finite element method. A smeared crack approach using rotating crack model without shear strain on the crack plane was employed. Based on this analytical work, the effect of the compressive strength reduction after cracking and the post-peak ductility in the constitutive law on shear fracture behavior for different shear-span ratios was discussed.
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Hiroshi HOSOYA, Yoshinobu ASANO, Yoshio OGAWA, Hiroshi IMAI
Article type: Article
2001 Volume 66 Issue 544 Pages
117-124
Published: June 30, 2001
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To facilitate construction of buildings, a precast concrete shell-form method applied to columns has been developed. The precast concrete shell is constructed by ordinary cast-in-place concrete, or is molded by centrifugal force. However, there is not much data regarding the structural characteristics of columns using the two types of precast concrete shell (hereafter referred to as PCa column). To investigate this, horizontal cyclic loading tests of PCa columns were carried out for structural characteristics and compared to conventional RC columns. Moreover, accuracy of calculated value of maximum strength of PCa columns by conventional method was investigated. It was confirmed that the structural characteristics of the two types of PCa columns were equivalent to that of the RC columns, and the maximum strength of PCa columns could be calculated correctly regardless of precast concrete shell type.
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Kazuhiro NAGANUMA, Osamu KURIMOTO, Hiroaki ETO
Article type: Article
2001 Volume 66 Issue 544 Pages
125-132
Published: June 30, 2001
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Nonlinear finite element analyses have been performed for reinforced concrete wall specimens subjected to reversed cyclic loads or dynamic loads. The analyses employed previously proposed stress-strain hysteretic model of concrete incorporated with a multi-directional smeared crack model that can take account of six crack directions. It is found that the analyses reproduce experimental load-displacement hysteresis loops with relatively good correspondence not only for the statically loaded specimens but for the specimen failed by the shaking table test. Time histories of acceleration and displacement responses are also simulated reasonably well by the analyses.
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Kiichiro SAWADA, Yan ZHOU, Akira MATSUO, Yuji NAKAMURA
Article type: Article
2001 Volume 66 Issue 544 Pages
133-139
Published: June 30, 2001
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The minimum weight design problem of steel frames considering member section's depth design variables is described in this paper. The algorithm that separately executes member section's depth optimization and cross section optimization is presented. The relaxation method is used in combination optimization of the member section's depth, and the sequential linear programming (SLP) method is used in the cross section optimization. 5-story frame and 10-story frame are designed by the presented method, and these frames are compared with the frames designed by genetic algorithm.
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Fumihisa YOSHIDA, Kenji FURUMI, Akira FUKUDA, Yoichi MATSUBARA
Article type: Article
2001 Volume 66 Issue 544 Pages
141-146
Published: June 30, 2001
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This paper describes the structural performance of H-beam to RHS-column connections reinforced by increasing column thickness. In order to investigate the strength and local deformation of the non-diaphragm beam-to-column connections, a series of tensile test is performed. In this test, the beam-to-column connections are simplified to beam flange-to-column connections. The column thickness is increased by induction heating procedure. The yield strength and ultimate strength formulae are developed, based on yield line theory. The formulae give reasonable agreement with the test results.
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Iori KANAO, Masayoshi NAKASHIMA, Dawei LIU
Article type: Article
2001 Volume 66 Issue 544 Pages
147-154
Published: June 30, 2001
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This paper presents a numerical study on lateral torsional buckling, out-of-plane deformation in the post-buckling regime, and strength deterioration of wide-flange steel beams subjected to cyclic loading. The maximum strength obtained in monotonic loading, maximum strength experienced during cyclic loading, and reserved strength after completion of cyclic loading were examined carefully, and the following observations were made, (1) Strength degradation due to load reversals is significant, and the monotonic maximum strength is not a reasonable measure to estimate the reserved strength achieved in cyclic loading. (2) Lateral bracing requirements stipulated in the present Japanese seismic codes are not adequate for beams in steel moment frames built in regions with high seismicity. (3) Lateral bracing lengths that ensure sufficient rotation capacity of wide-flanee beams are proposed.
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Hitoshi KUWAMURA, Yuichiro INABA, Ayumi ISOZAKI
Article type: Article
2001 Volume 66 Issue 544 Pages
155-162
Published: June 30, 2001
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Local buckling behaviors of thin-walled stainless steel stub-columns were experimentally investigated. Six types of sections, i.e., angle, channel, lipped channel, H-shaped, square box, and circular sections were tested. These specimens were formed from two grades of austenitic stainless steels designated SUS304 and SUS301L 3/4H, whose specified yield strengths for design are 235 and 440N/mm^2, respectively. Effective width-to-thickness ratios of unstiffened and stiffened plate elements and limit diameter-to-thickness ratios of circular cylinders were established from the test data. It was found that the effective width-to-thickness ratios must be expressed by different equations for the two strength grades, because of the difference in strain hardening.
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Junichi SAKAI, Chiaki MATSUI, Koichi MINAMI
Article type: Article
2001 Volume 66 Issue 544 Pages
163-169
Published: June 30, 2001
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A numerical analysis for elastic-plastic behavior of core steel composite columns with considering buckling of main bars was carried out. In this paper it is shown that the results of the analysis agree with the experimental results, and the core steel composite columns under large axial force can hold axial load up to large deformation, but RC columns can not hold at last. Moreover, the effects of area and shape of cross section of core steel and axial force on the seismic performance of core steel composite columns are discussed.
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Takeshi MORITA, Akira NISHIDA, Hiroshi HASHIDA, Nobuyuki YAMAZAKI
Article type: Article
2001 Volume 66 Issue 544 Pages
171-178
Published: June 30, 2001
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The destructive spalling of concrete during a fire may cause a reduction of load bearing capacity and fire separating capacity of building elements. The objective of the study is to get practical knowledge of spalling, which is necessary for structural fire design of reinforced high-strength concrete elements. To achieve the objective, the spalling behavior of concrete under high temperatures was experimentally studied. The study gave practical knowledge for quantitative evaluation of spalling degree of reinforced concrete elements, improvement of spalling resistance of high-strength concrete by adding synthetic fibers and a design index for finding a proper quantity of synthetic fibers.
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Shuichi ASAYAMA
Article type: Article
2001 Volume 66 Issue 544 Pages
179-187
Published: June 30, 2001
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This paper describes fundamental issues on responses of the new type of structures governed by nonlinear equations using one mass system with nonlinear histeretic curves. Differential equations with terms on nonlinear restoring forces idealized by hard and soft springs were solved directly by Runge-Kutta method and the numerical results were compared with those acquired approximately by combination of linear equation and equivalent spring. Exciting ground motions are sinusoidal waves, El Centre 1940, Hyogo-ken Nanbu Earthquake of 1995 and Miyagi-ken Oki Earthquake of 1978. Finally the author concludes chaotic phenomena often exists in response of this type of structures and viscous damping can be thought effective to control the nonlinear phenomena and to make the system stable.
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Motoichi TAKAHASHI, Tadashi NASU
Article type: Article
2001 Volume 66 Issue 544 Pages
189-
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The purpose of the paper by the author is to verify the effectiveness of the variable stiffness device having elastic non-linear characteristics through the static experiment using actual variable stiffness device and the earthquake response analysis. However, the conclusion drawn from the earthquake response analysis is inconsistent with the purpose, thus making the intention of the paper unclear.
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Hideo SUITSU
Article type: Article
2001 Volume 66 Issue 544 Pages
190-
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The author thanks Motoichi TAKAHASI and Tadashi NASU for their discussion, and the answers are as follows: The paper reports the elastic non-linear characteristics of the variable stiffness devise and its efficiency during earthquakes. Concerning the reduction of the seismic response, non-linear type is better than linear type on the elastic phase, and inelastic type is better than elastic type on the non-linear phase. Therefore double measures, non-linear variable stiffness device and dumping device are recommended.
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Article type: Appendix
2001 Volume 66 Issue 544 Pages
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Article type: Cover
2001 Volume 66 Issue 544 Pages
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