This paper deals with the influence of conveyance vibration on compressive strength of specimen of high-strength concrete. In the experiment, six kinds of concretes (water binder ratio is 60% to 20%) were examined. Conclusions are as follows. (1) The conveyance vibration affects compressive strength of specimen. Immediately after production of concrete, conveyance vibration causes strength reduction of specimen. Then, if concrete begins to harden, conveyance vibration will contribute to the improvement in compressive strength. Furthermore, if time passes too much since production of concrete, conveyance vibration will cause strength reduction. (2) Concrete with low water binder ratio is hardly subject to the influence of conveyance vibration. One of the reasons of this is that water and air hardly move in concrete with low water binder ratio. (3) It is not desirable to carry a test specimen immediately after mixing of concrete. Moreover, after time passes very much since mixing of concrete, it is not desirable to carry a test specimen, either.

View full abstract

The purpose of this study is to evaluate the effect of fiber orientation in HPFRCC (High Performance Fiber-Reinforced Cementitious Composite) to its tensile behavior. The cylindrical core specimens are extracted from HPFRCC specimens which have different sectional size. These core specimens are operated with X-ray CT scan system and fiber in HPFRCC is visualized. The fiber orientation angle is obtained from the visualized images and the fiber orientation angle distribution is evaluated by newly defined probability density function characterized by “orientation intensity”. The fiber orientation has the tendency that the fiber is oriented toward the parallel direction to matrix flow. The calculation for bending strength is carried out using the proposed evaluation method and the result can express the tendency of the size effect of experimental results.

View full abstract

In theoretical and applied mechanics are there many problems with mixed-boundary values. It is difficult to solve them analytically. These days FEM technics are used to solve them. FEM technics could give numerical answers under some assumption on the modeling to be analyzed. But it is a demanding job to evaluate errors of the numerical results. In this paper analytical solutions and their numerical results of a mixed-boundary-value problem have been derived. The authors have used some kinds of potential functions with Fourier-Transform technics for deriving analytical and numerical solutions on the interaction between the building foundation and the surrounding soil ground. They propose that these results gained above could be standards of judgment for FEM's accuracy, too.

View full abstract

The feature of great subduction plate-boundary earthquakes such as the 2011 off the Pacifi c coast of Tohoku, Japan, earthquake (M_W 9.0) and the 2004 Sumatra earthquake (M_W 9.1) is that the short-period motions were generated on the deeper part of the fault and the long-period motions on the shallower part. Hence, we compiled the fault parameters of past subduction earthquakes and showed their scaling laws. Then, we proposed a procedure for making a consistent fault model both for the deeper part and the shallower part, applied our new procedure to the large subduction earthquake (M_W 9.1) along the Nankai trough off the Pacifi c coast of the West Japan, and showed four examples of the fault models including several asperities. Based on the four examples, we simulated ground motions in and around Nagoya City by the empirical Green's function method, and compared the seismic intensities of the simulated motions with those in the past three Nankai trough earthquakes.

View full abstract

This paper presents the simulation analysis about damage of structure supported by pile subjected to very large seismic motion during the 1995 Hyogoken-Nambu Earthquake by 3D-FE analyses considering an effect of non-linearity between pile and soil. The input motion is evaluated by the observed record and 2D-FE analysis using the deep irregular under-ground model with vertical discontinuity. The major finings obtained from analyses are summarized as follows:1) the FE analysis can simulate the distribution of damage of pile cap in the observation in which the pile in group of 2 piles was damaged heavily, 2) In the instance, the subgrade reaction for pile in group of 2 piles is larger than in group of 3 or 4 piles, furthermore the subgrade reaction for pile in group of 3 or 4 piles is affected by the behavior of the adjacent build-ing and decreases. These may be causes of the distribution of damage of pile cap, 3) the pile cap damage in the instance may be caused by the piles were subjected to the very large inertial force and the ground displacement at the same time.

View full abstract

It has been proven that the displacement controller which has hardening type hysteresis can reduce the displacement of frame or isolation layer against the huge earthquake from many experimental or analytical results. However, it is difficult to evaluate the changes in response characteristics with various qualitative parameters. The purpose of this paper is to evaluate the response characteristics of the flexible-stiff mixed structure with displacement controller qualitatively and simply. Energy balance-based seismic response prediction method proposed by Prof. Akiyama is extended to the structure with displacement controller, and this method is validated through many time history response analyses using the single-degree-of-freedom model. In addition, the estimation method for the passive controlled structure and the isolated structure with displacement controller is shown respectively, and the effectiveness of this method is demonstrated by analyzing time history analysis results and estimation results.

View full abstract

This paper aims at quantifying the influence of the uncertainty associated with the natural circular frequency and damping factor. The theoretical analysis dealt with the stationary random process of the SDOF system under the assumption that the natural circular frequency and damping factor are independent and uniformly distributed. Then the influences of the fluctuation of these parameters were quantified for some probabilistic indices. Numerical means was also used to investigate in detail the distribution of amplitude. It was found that the distribution is quite similar to the contaminated Gaussian distribution.

View full abstract

This paper discusses on a control method of vertical and horizontal micro-vibration of a frame using film type piezo-electric devices at the lower flange of the beam end. The theoretical controlling force acting on the frame is calculated using the material characteristics of steel plate and the film type piezo-electric devices. The actual controlling force is estimated through the excitation test of a reduced frame model and finite element analysis. Through the micro-vibration control test, the possibility of controlling vertical and horizontal micro-vibration of the frame with the proposed method is proven.

View full abstract

Devises using the rolling of viscoelastic materials such as rubber is proposed, and a practical procedure for easy evaluation of the rolling resistance of them is required. This kind of research has been already established in the field of tire technology, and many patents are submitted. One of the approaches to simulate the rolling resistance of viscoelastic materials is to calculate the energy dissipation of a rolling model from the strain and stress obtained from a finite element-based method of an elastic model, and the loss factors of the material determined separately. In this paper, a new devise using the rolling of O-ring rubber is proposed and the method of simulating the rolling resistance of viscoelastic materials is applied. Compared with an experiment and dynamic finite element analysis, the validity and the qualitative aspects of the proposed method are discussed.

View full abstract

A numerical method for the analysis of the free vibration behavior of cantilevered thick cylindrical shells with skewed fixed end using the Rayleigh-Ritz approach is presented in this paper, together with some numerical results. The method is based on the three-dimensional coordinate system by considering rotating inertia and shear deformation. Numerical results are compared with the results of FEM approach, and the comparison shows the method presented in this paper to be useful for analyzing the free vibration of cantilevered thick cylindrical shells with skewed fixed end.

View full abstract

The seismic behavior of a pile-supported building with semi-rigid pile head connections in liquefiable soil is investigated using 2D effective stress analysis. The results of the simulations show that the pile damage reducing effect of the semi-rigid pile head connection method is enhanced in liquefiable soil, because the superstructure inertia and external force acting on the embedded footing decrease. And the validity of the seismic deformation method as a seismic design method, which considers the non-linearity and axial force dependency of the pile heads, the varying axial force due to the dynamic interaction, and the total earth pressure acting on the embedded footing, is confirmed.

View full abstract

It is important to accurately estimate the effects of the building basemat uplift and structural response for strong earthquake motions in seismic design of nuclear power plant buildings. In this paper, dynamic centrifuge tests were performed using rigid structure on sand and clay deposits to investigate the difference of structure response due to difference in the bearing stratum, and effect of adhesion between basemat and clay deposit. It was shown that (1) the adhesion was effective in suppressing uplift; (2) the building on sand and clay deposit showed different earthquake response; (3) the JEAC equation for ground contact ratio gave a safe side estimation.

View full abstract

This paper describes the evaluation method on the resistance of a nodular part for nodular cast-in-place concrete pile acting both compressive and tensile loads in sandy ground. The resistance of a nodular part is properly separated into three components, the shear resistance of cylindrical area, Rs , the bearing pressure of circular area, Rtb , and the shear resistance of inclined area due to the increase of horizontal stress, Rts . The validity of the evaluation method were examined by comparing the calculated values and the results of in-situ vertical loading tests.

View full abstract

The present paper discusses on elastic buckling load and ultimate strength of reticulated cylindrical roofs under uniform lateral loads in the case of two boundary conditions of simple support and pin support. First, classical buckling load under a uniform lateral load is newly derived mathematically based on a simple approximation, followed by comparison with the linear elastic buckling loads calculated using FEM analysis. The comparison is performed to find approximate relations between the classical buckling loads and the FEM linear buckling loads for simple support and pin support. Second, elastic buckling loads are investigated based on FEM analysis considering geometrical imperfections, followed by derivation of formula for imperfection sensitivity which enables engineers to evaluate elastic buckling loads with hand calculation. Third, elastic plastic buckling loads are investigated based on FEM analysis also considering geometric imperfection, and the imperfection sensitivity of elastic plastic buckling loads is formulated mathematically. Finally, an estimation procedure for elastic plastic buckling loads is proposed based on the elastic buckling loads and the imperfection sensitivity for elastic plastic buckling loads in the two cases of boundary conditions.

View full abstract

This Five Story Wooden Pagoda is high rise structure existing from ancient times to now. In this study, new observation systems consisting of image processing and vibration sensors was used. The five story pagoda which is national heritage and constructed in 1622, locates at the site of Hokekyouji Temple in Ichikawa city, adjacent to east side of Tokyo. Earthquake response observation indicated the dynamic relative displacement of 75mm in 0.2G ground motion in maximum. Wind response observation indicated the dynamic relative displacement of 40mm in wind speed of more than 30m/s, using high frequency pass filter of 0.3Hz. During large displacement response, the dominant period showed the increase from 1.25sec to 2sec. There were no major difference between the center column and the pagoda frame.

View full abstract

The objective of this research is to analytically estimate seismic responses, in particular maximum drifts of earthquake-damaged RC buildings. A predominant period obtained by ambient vibration measurements and a residual seismic capacity ratio index R based on damage classes of columns were applied to evaluate a maximum drift of an example of earthquake-damaged buildings. As a result, the proposed method based on the R -index approximately reproduced damage to columns in the most severely damaged story, while the other method by the predominant period overestimated. Characteristics and scope of both methods were also investigated through the application above.

View full abstract

The influence of the stress in a direction perpendicular to the bar on bond strength has already been studied a lot in association with lateral reinforcement, however, the influence of the axial stress has not been clear yet. In this study, a brush type loading equipment was used in order to reduce the friction and pull-out tests were conducted with the concrete under axial compression. The parameters were concrete cover thickness, lateral reinforcement ratio, and axial force ratio. The results show that bond strength decreases with the increase in the axial force ratio in the case of no lateral reinforcement, and the load with which the first crack occur decreases with the increase in the axial force ratio regardless of the exist of lateral reinforcement.

View full abstract

In this paper, the structural characteristics of beam-to-column connection under bi-axial loadings are investigated by FEM analysis. Parameters are the structure shape and the loading pattern. First, the elasto-plastic behavior of each column, beam and joint panel in structure are investigated. Next, it is clarified that the plastic deformation of joint panel gives the influence to the elasto-plastic behavior of the flange connected part and the web connected part at beam-end. The analysis results show that the plastic deformation of the joint panel is a factor that reduces the bending strength of the beam-end. Finally, the full plastic bending strength of beam-end is evaluated by taking into consideration the influence of the plastic deformation of joint panel.

View full abstract

This paper presents the behavior of offset beam-to-column connection panels with exterior diaphragms. The plastic strength of panel is proposed based on two collapse mechanisms of the connection panels. One of the mechanism is only panel yielding type which is the same as the standard panel. The other is a mechanism by a combination of yielding in some parts such as panels, exterior diaphragms and column tube wall. The yield strength of panel is derived from conditions of stress corresponding to when the panel, which is connected by beams in both sides, initially reaches yielding. In order to confirm the applicability of the strength, cyclic loading tests of cruciform subassemblages were conducted. The major findings obtained by the test are summarized as follows: 1) the strength and stiffness of offset panels could be properly evaluated by the proposed formulae, 2) the characteristics of panels have been stable and shown no remarkable deterioration up to large deformation, 3) the assumed collapse mechanisms were in good agreement with the test results.

View full abstract