Based on the disjoining pressure concept, volume change of hardened cement paste is investigated. As the hardened cement paste shows a hysteresis regarding adsorption and desorption isotherm, disjoining pressure of water in hardened cement paste was evaluated with the proposed equation led from equilibrium between disjoining pressure of water and elastic force of skeleton. As a result, all the relationships between averaged thickness of adsorbed water and disjoining pressure of water were on the same curve, and using this potential curve, volume change of hardened cement paste can be simulated. With the same concept, disjoining pressure curve was evaluated with cement paste containing shrinkage reducing agent, and it was experimentally confirmed that shrinkage reducing agent decrease the gradient of disjoining pressure curve and this curve cause the smaller shrinkage strain during drying process.

抄録全体を表示

The purpose of this study is to evaluate a water-supplied area from the saturated lightweight aggregate in high strength concrete. For this objective, phenomena of water transfer between cement paste, whose water to cement ratio is 0.25, and aggregates is visualized by neutron radiography technique. The parameter of this test was the type of aggregates, namely, saturated lightweight aggregate, air dried lightweight aggregate, and ordinary sandstone. Additionally the steel is also tested for understanding the ‘wall-effect’.
Experimental results show that water supply from saturated lightweight aggregate continued upto more than 14days, and the water supplied area of cement paste was ranged within 4mm from the aggregate surface, and air dried lightweight aggregate suck the water from cement paste upto 12 hours and that water was released after 24 hours. Reduction of water content in cement paste, which was seen in both the test with steel and ordinary sandstone, was ranged within 1.2mm from the surface.

抄録全体を表示

This study discusses the long-term strength gain of Ecocement with ground granulated blast-furnace slag that it examined the influence of curing temperature. As a result, it was able to be confirmed that the long-term strength gain of Ecocement with ground granulated blast-furnace slag is improved regardless of the curing temperature. Results of pore size distribution, Ecocement with ground granulated blast-furnace slag was acknowledged densification of pore volume. This study had a high correlation between a decrease in the pore volume of 0.01µm or more and compressive strength , it was clarified that the long-term strength gain had improved because of a decrease in these pore volume.

抄録全体を表示

The analysis of loading on the chloride penetration into concrete is very important. In this study, we confirmed that the chloride penetration rates for the plain and BFS concrete were increased by 47% and 89% under the compressive stress, respectively. Under the tensile stress, those for the plain and BFS concrete were increased by 29% and 77%, respectively. The diffusion coefficient of BFS concrete was lower than the conventional one with no BFS no loads and stress states. Under the compressive stress, the diffusion coefficient for BFS concrete was higher with increasing stress as well as the plain concrete. Under the tensile stress, the diffusion coefficient for BFS and plain concrete showed higher values with increasing stress. We investigated the effect of the difference of specific surface on diffusion coefficient. As a result, the larger specific surface of BFS exhibited the lower diffusion coefficient. This tendency showed remarkably under the high stress conditions. We confirmed that the diffusion coefficient was lower with increasing the ratio of substitution BFS. This result was the same even under the compressive and tensile stress conditions. The chloride penetration depth was distributed uniformly under the compressive stress or no stress. However, in the case of the tensile stress, the diffusion distribution of chloride ion penetrated into concrete was no uniform, and I showed the prominent characteristics. This result indicates that the analysis using by average values is not proper under the stress conditions.

抄録全体を表示

The rheological properties of cementitious materials are important to evaluate the workability of cementitious plastering materials. The properties of fresh cementitious materials conform the Bingham model which has a plastic viscosity and a yield stress. The purpose of this study is to evaluate the rheological properties of fresh cement pastes and fresh cement mortars by a viscosity index and a yield stress index measured by the inclined blades rotational rheometer which was developed by authors in previous study.
As a result, it was found that the mixing conditions and the material properties influence rheological behavior of fresh cementitious materials; as increasing water-cement ratio and reducing sand-cement ratio, both the viscosity index and the yield stress index decrease. The viscosity index increases with rising methylcellulose-cement ratio and superplasticizer-cement ratio. Moreover, the yield stress index is related to a flow value measured by the table flow test.

抄録全体を表示

Depth impression is one of the expressions which gives high quality and good appearance of materials. But there is no scale for evaluating it. In this paper, the effect of surface properties on the depth impression of building stone finishing was investigated. Sensory tests were performed using natural stone specimens which varied in stone type, surface finishing method and surface pattern. The visual depth of glossy and glittered surfaces was further analyzed by performing sensory tests using seven grades of polished black granite. Physical values of luminance factor were measured by multi spectral imaging, the relationship between it and the results of sensory test was considered. It was cleared that the depth impression was related to the L*and physical gloss(60°). Depth impression, metriclightness, visual expensiveness and massiveness were related to the luminance factor. As variation in luminance factor and surface color were even, an observer felt depth.

抄録全体を表示

From the standpoint of the maintenance of ALC-buildings and management, the ability of ALC panel to be reused after being subjected to fire is likely to become an important issue. In the research described here, the bending strength of ALC panel of various thicknesses after heating was studied. As a result, the rate that the bend increases by the influence of heating is calculated from the experiment value compared with non-heating panel, and it proposes the expression that calculates the increase ratio of the bend from the relation between the heating time or heating change depth of tobermorite of ALC and the panel thickness after heating.

抄録全体を表示

We estimated the damping ratio of a tower-and-conductor system by combining several identification methods and full-scale measurement data which contain many components of close frequencies of the system vibrating under strong winds. Our procedure was able to extract the component of every vibration mode of the tower from a time history of the measurement data and estimated more accurate damping ratios individually. Moreover we discussed the effects of the progressive deformation of a transmission-conductor-plane due to an increase in wind speed on the development of the aerodynamic damping of tower-and-conductor system using a three-dimensional nonlinear analysis.

抄録全体を表示

We hypothesized that the scale of the predicted Nankai Earthquake will increase gradually year by year as the time from the last occurrence in December 1946 lengthens, and then we estimated strong ground motions chronologically from 2009 to 2060 for the western Japan. Next, we input the derived chronological strong motions into nonlinear building models and estimated building damage rates for different structure types and numbers of floors. At the same time, we estimated the areas and existing ratios of different building types in the subject regions chronologically, and we conducted "evolutional building damage predictions" for the period from 2009 to 2060 using these statistical data and the derived chronological damage rates. Finally, based on the calculated damaged building areas, we comprehensively calculated the amount of CO₂ emissions from construction waste and the resources and energy necessary to restore those damaged buildings, making clear the extent of the environmental loads of the predicted Nankai earthquake scenarios in comparison with the CO₂ target values set by the Kyoto Protocol of COP3.

抄録全体を表示

This paper discusses the motion characteristics of building structures with soft stories integrated, from the wave propagation point of view. Even in dealing with a normal lumped mass system, if considering the energy transfer from a lumped mass to its next lumped mass, a very clear view can be given to the understanding of the mechanism for the vibration phenomena for these structures. In particular, the paper focuses on why a significantly large deformation occurs at the soft story in these structures. In addition, the relationship between the peak seismic deformation and energy flows in the structures subjected to large-period seismic excitation is quantitatively discussed from the standpoint of energy transfer induced by the wave propagation through the structures.

抄録全体を表示

This paper studies the effect of spatially random ground motions on the seismic response of a one-story multi-span wooden building considering the stiffness of the horizontal diaphragms. The deformation angles at columns and horizontal diaphragms are examined using time history response analyses with simulated input motions. It is shown that stiffness increase of the horizontal diaphragms and dimensions increase of the building make responses large to damage, and that large responses at the horizontal diaphragms are much more serious than at columns.

抄録全体を表示

In this paper, a new stiffness-damping simultaneous identification method for a building structure is proposed when the building includes an unknown inner vibration source. The feature of this method is that the present identification can be performed even though the location and time-history of the vibration source in addition to all stiffness and damping coefficients are unknown. By performing limit manipulation, the relations between stiffnesses of consecutive stories and those between damping coefficients of consecutive stories can be obtained from the acceleration data at the floors just above and below the object story which can be recorded by using at least two sensors. The level of stiffness and damping coefficients can be determined to satisfy the recorded lowest natural frequency and the lowest damping ratio. The validity of the proposed method is examined through numerical examples using theoretical data and actually recorded data.

抄録全体を表示

In this paper, comparison is made between vibration control systems using viscous damper, viscous mass damper and tuned viscous mass damper. It is shown that the vibration control system using the viscous mass damper is the most effective for linear structural system with the dampers having same damping ratio. Effectiveness of the present vibration control system is verified conducting shaking table tests with small scaled tuned viscous mass dampers.
And, applicability of the present vibration control system to non-linear structural systems subjected to seismic ground motions is also shown by performing non-linear time history analyses.

抄録全体を表示

Strain-dependent shear moduli of cohesive soils at K-NET Anamizu and JMA Wajima were estimated using the strong ground motions recorded in the 2007 Noto-Hanto Earthquake. The estimated shear moduli of the soils are in good agreement with those measured in the laboratory for the soil samples obtained from the sites, when the generated pore water pressure is taken into account. The pore pressure ratios induced by the main shock were estimated to be 0.4 at Anamizu and 0.3 at Wajima, suggesting that not only the cyclic shearing but also pore water pressure generated during earthquake shaking could have strong effects on the shear modulus reduction of cohesive soils.

抄録全体を表示

Passive control of light-gage steel frames is discussed. Disadvantage of the conventional frame having tension braces are explained and the viscoelastic damper is applied instead of the brace. The passive control frame is modeled as spring and damper connected in series. And it is important to increase the spring stiffness for the performance of the passive control. Procedure to decide the damper size is proposed and a frame having the viscoelatic damper is developed. The performance is validated through the dynamic loading test. Shaking table tests are also conducted to three specimens that have the damper and/or the tension brace. Response characteristics of specimens are evaluated using the seismic response spectrum and the time-history analysis.

抄録全体を表示

In this paper, we present a method for controlling the distribution of optimal member sections for a steel frame. The smoothing parameter is selected by using Bayesian Information Criterion, which is called ABIC. The checkerboard problem refers to the formulation of regions of alternating large and small elements ordered in a checkerboard-like fashion. The checkerboard problem can be avoided with the presented method. The validity of the method is demonstrated by numerical examples of the plane steel frame model.

抄録全体を表示

The objective of the present study is to investigate the effects of the physical properties and confining stress on the Sr-P-wave velocity and Sr-liquefaction strength correlations for sandy soils. Based on a series of laboratory tests, following were concluded. (i) The effects of relative density, particle size and shape, pore water property and over consolidation ratio on Sr-P-wave velocity correlation is negligible. (ii) In the range of Sr smaller than 95%, P-wave velocity increases with increasing confining stress. (iii) P-wave velocity increases rapidly when the degree of saturation increases from 90% to 100% regardless of the physical properties of sand and confining stress. (iv) The effects of the confining stress and physical properties of sand on the correlation between the degree of saturation and liquefaction strength are minimal. (v) A decrease of Sr from 100% to 90% brings about 2.2 times increase of liquefaction strength unaffected by the physical properties of sand and confining stress. (vi) A decrease of Vp from about 1600 m/s to 350 m/s brings about 2.2 times increase of liquefaction strength.

抄録全体を表示

To investigate effects of existing piles on the vertical bearing capacity of new piles, when piles of an old building left derelict, vertical loading centrifuge tests were performed on a new pile located at the center of 2 × 2 existing piles. Results suggest the following conclusion:(1) The existing piles increase the shaft resistance of the rough surface new pile, because the confining pressure around the new pile increases. (2) The existing piles do not affect on the shaft resistance and point load of the smooth surface new pile, because the confining pressure variation around the new pile is small.

抄録全体を表示

Embedments of foundations influence the safety of buildings supported by piles during earthquakes. Dynamic centrifuge tests were conducted to investigate the influence of soil liquefaction beneath foundations to seismic earth pressures acting on embedment. The following conclusions were obtained: (1) liquefaction of soil layer beneath the foundation reduces the seismic earth pressure acting on embedment; (2) the existence of non-liquefied layer beneath the foundation reduces the effect of liquefaction on seismic earth pressure; (3) hysteresis damping factor is not influenced by the liquefaction of soil layers beneath the foundation.

抄録全体を表示

The objective of this study is to propose a calcuration method of tensile axial force acting on connections at top and bottom sheathed shear walls in timber wall structures. And the method is applied to practical design for light frame construction, simplified formulae using shear resistance factor are derived. The formulae are composed of three terms, and the axial force can be shown as the sums of vertical shear force in the shear wall, dead load, and additional force from the overturning moment generated in the boundary beam. The method and the formulae are confirmed by full-scale racking tests of 2-story walls of light frame construction. Concluding remarks are as follows: 1) The method can be applied to tha varieties of the shape of sheathed panels. 2) The method can be also applied to the varietied of disposition of walls in stories. 3) Calcuration values that uses existing stress and shear resistance factor are coincident satisfactorily with the experimental values.

抄録全体を表示

Modeling of joint part of wooden houses is important because the structural behavior of the joint part have a large influence on that of wooden frame. The objective of this study is to provide the hysteresis model of the joint part by considering the hysteresis of its fundamental structural component such as screws and holddown bolts. Based on the experiments about the fundamental structural component, the hysteresis were modeled for cross-section analysis. Cross-section analysis could predict the axial force-axial displacement relationship and the moment-rotation relationship. Hysteresis model of the joint part was proposed based on the cross-section analysis. The reliability of the hysteresis model was confirmed by the comparison of shear loading test of wooden frame.

抄録全体を表示

The calculation method for the shear strength of shear walls was shown in [Design Guidelines for Earthquake Resistant Reinforced Concrete Buildings Based on Inelastic Displacement Concept] published by ARCHITECTURAL INSTITUTE OF JAPAN (following, called AIJ equation). The calculated results by AIJ equation correspond with experiment results. But, the assumption that all horizontal bars in shear walls yield when shear walls reach at shear strength does not correspond with real phenomena. So, the new calculation method was developed. In the proposed method, the shear strength was determined with concrete compressive strength or horizontal bars yield strength. The calculation results by the proposed method corresponded better with experiment results than AIJ equation.

抄録全体を表示

In this paper, we discuss tensile strength of kinds of splices of reinforcing bars in recent years. As we could anew obtain more than 200,000 tensile test data carried out in Kinki-area and Tokyo area during 2004-2007, the data were compared with the previous 1982-1986 data on gas pressure welded splices in Tanaka's research.[1] As a result, failure ratio, that is the ratio of the number of specimens ruptured at the part other than mother bars, is reduced from 0.52% to 0.13% as for SD345 and it is 0.32% as for SD390, however, the splice of bars with bigger diameter and higher tensile strength show higher failure ratio as before. We also reconsidered the strength distribution of the splices and proposed a probability density function expressed as eq.(7) assuming a simple stochastic process.

抄録全体を表示

In order to investigate the effect of loading rate on the hysteresis response of R/C framed shearwalls (hereafter referred to as Shearwall), we conducted the lateral loading tests on the 1/4 scale model shearwalls. The specimens were subjected to the reversed cyclic lateral load under a constant axial load. The experimental variables included in the test series were loading rates, failure modes and loading path. The flexural yielding failure mode and the shear failure mode were planned. The increase rate of lateral load carrying capacity due to the increase of the loading rate was larger in shear failure mode than in flexural yielding mode.

抄録全体を表示

In this study, we propose a new consideration of seismic reinforcement using a single angle brace joint.
The load-carrying capacity of such joints was investigated by applying tension stress to them until an angle member section became fully plastic. In this case, the earthquake input energy was used enough for the plasticity of the angle members. However, this structural design has one limitation: if the joints do not have sufficient load-carrying capacity, they will break before yielding. This decreases the ductility of the structural frame. Therefore, structural designers have to ensure that a single angle brace joint has sufficient load-carrying capacity. However, the stress transmission characteristics of an angle brace joint have not yet been clarified sufficiently.
In seismic retrofit based on design guidelines, the index of ductility is determined based on a two-level evaluation of the joint strength. The authors have confirmed the reliability and validity of this method from the results of online seismic response tests and considerations concerned with the material yield ratio.

抄録全体を表示

To clarify post-earthquake fire resistance of steel frames, this paper studies analytically the ultimate temperatures of seismically designed multi-story and multi-span steel frames which have suffered some or severe damages due to preceding earthquakes. Refined finite element analysis and simplified theoretical analysis have both been conducted assuming that the frames, which have undergone permanent relative story displacement and/or fracture of beam-end-connection due to earthquakes, are next subjected to whole floor fire at the first floor. It is found that the lowering in ultimate temperature of the damaged frames is caused by P-Δ effect depending on the amount of the residual relative story displacement of the floor in fire. Their ultimate temperatures are therefore affected solely by the amount of axial forces and slenderness ratios of columns, but they are almost independent of the number or length of spans or of the number of stories. Theoretical consideration aims to analyze simply the post-earthquake P-Δ effect of the heated columns and the resulting predicted ultimate temperatures are found in good agreement with finite element solutions for all cases.

抄録全体を表示

We create a hazard map of Route-to/from-School for stone masonry walls in Kure city based on an earthquake scenario in order to indicate the danger zone for the public. The seismic stability of the stone masonry walls is evaluated using DDA (Discontinuous Deformation Analysis), which is a type of discrete element method and suits to solve the large displacements accompanying the discontinuous movements between blocks. First, we survey the detail of the stone masonry walls along the Route-to/from-School and examine the accuracy for simplifying the analytical model. Then, we estimate the seismic stability and possible dispersed areas of the stones from the collapsed walls based on an earthquake scenarios. Finally, we create a hazard map of Route-to/from-School for stone masonry walls in Kure city.

抄録全体を表示

Tests on shear corrugated steel plates were carried out to examine effect of shape and thickness of cross section on end failure action that may occur at the ends of flutes in shear diaphragms. Based on the test result and observation obtained through this research, previous deformation model for stiffness estimation were reviewed, and the deformation model were developed into strength model with application of yield line hinge. Strength design formulas were derived from the strength model using a limit analysis technique. Comparison with the test results showed that the derived formulas provided appropriate stiffness and strength estimation.

抄録全体を表示

An experimental study was conducted to evaluate the effects of high temperature and strain rate on the compressive behavior of steel H-section stub-columns at high temperatures. On the basis of the experimental results obtained in this study, it was found that the ultimate load and the post buckling behavior of H-section stub-columns decreased with increasing the temperature and width-to-thickness ratios. The ultimate load of columns at 600 Celsius was reduced to 40 to30% of the maximum load at room temperature and was very sensitive to the strain rate. But the ultimate load was not sensitive to the width-to-thickness ratio at high temperatures. The results of tests at high temperatures were simulated by a numerical procedure. The results of the calculations clearly showed that numerical analysis can be used to provide accurate predictions of the local buckling characteristics of stub-columns at high temperatures. It was also shown that the effects of strain-rate on the post-buckling behavior of steel stub-columns at high temperatures cannot be disregarded.

抄録全体を表示

This paper presents results of flexural and shear tests in order to examine the effect of fire heating on the seismic performance of reinforced concrete columns using concrete with a compressive strength of more than 100N/mm². Several fire protection measures were applied to these reinforced concrete columns before being exposed to fire for three hours. The following conclusions were obtained from these tests.
1) As the columns were exposed to higher temperatures, so the strength remaining after fire heating decreased. With the fire protection measures used in this study stiffness reduces to 60%-90% of initial values, while strength reduces to 60%-80%.
2) In addition, as heated temperatures increased, the failure modes shifted from the bending failure to shear failure.
3) A formula was developed which could indicate the tendency of the decrease in strength decline after exposure of the reinforced concrete columns to fire depending on heated temperature in the reach of this experiment.

抄録全体を表示