The interior of a high-strength concrete member is heated and cured under high-temperature condition in early ages by internal storage of the heat of cement hydration. This high-temperature curing affects the strength development of concrete. This paper describes a study on the properties of temperature rise and strength development of concrete in high-strength concrete members with different shapes and section sizes. In addition, this study clarified the effect of high-temperature curing in early ages on the hydration of cement and the microstructure formation of hydrated cement paste.

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Experimental studies were performed about a long-term length change and carbonation of high strength concrete. The concretes with water-binder ratio of 15-65% were examined. The following conclusions were obtained as results of examination. 1) Length change and weight change of concrete at 6 months became so small that a water-binder ratio becomes low. 2) When the water binder ratio became low, length change of the concrete continued long time. 3) By the accelerated carbonation test, the water portoland cement ratio of the concrete that is not carbonation at 26 weeks was less than about 40%. 4) Even if accelerated carbonation test results of long-term was used, depth of carbonation could be expressed by the function of the square root of age.

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The authors have proposed an empirical formula for predicting the relationships between compressive strength and void ratio of porous concrete in the previous paper. Main purpose of the present study is to discuss the effects of binder strength and aggregate size on the strength-void ratio relationships, based on the experimental data. Two series of experiments have been carried out, and the following results have been found. 1) The compressive strength of porous concrete at a constant void ratio is dependent on the binder strength and the aggregate size, while independent on the flow value of binder. 2) The earlier proposed formula for the prediction of compressive strength-void ratio relationships is found to be applicable to porous concrete tested in the present study.

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In this paper, a new method to predict the critical deformation of composite materials with interface cracks under mixed mode conditions by stress intensity factors K_1 and K_2 is presented, and also fracture criterions of the interfaces between concrete and cementitious wet-finishings are evaluated. Two kinds of stress intensity factors are based on interfacial fracture mechanics. Stress distribution and singularity on the interface between dissimilar materials are obtained by two-dimensional boundary element elastostatic analyses under a plane strain state. Two kinds of stress intensity factors determine the mixed mode fracture criterions of the interfaces. Predictions about delamination initiation and extension by these factors are compared with the results of observations made by compressive tests on composite model specimens that consist of several kinds of finishings. It was clarified that critical deformation could generally be predicted by the presented method.

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The formulation for time-dependent reliability analysis of structural member and structural systems, where the stresses are expressed by a linear function of acting loads, is developed in the previous study(Ref.1,2). This paper is fundamental study to establish probability-based limit state design of framed structures with several failure modes and describes the formulation as a system reliability problem for determining the load and resistance factors and the reliability function for each failure mode of framed structures with resistance deterioration due to aging under load combination consisting of dead, live, snow ,wind and earthquake loads, applying the advanced first order and second moment method with the statistics of the residual resistance of each failure mode of framed structures which has survived up to time τ during its service life.

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This paper discusses the methods to compare the relationship between the strong motion indices and damage of structures. Based on the rank correlation analysis for the dynamic analysis results, it is pointed out that the correlations could change depending on the damage levels and the structural periods. In the nonlinear time history analyses, the responses of wooden structure models of Single-Degree-of-Freedom (SDOF) were simulated for nine hundred input motions. It is observed that the responses of the linear SDOF systems with 20% damping ratio and with elongated periods, considering the damage thresholds, show fairly good correlation with the damages.

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This paper describes development of a new designed oil damper and research depends on various factors on an analytical of it. Recently, oil dampers have been used frequently for reducing vibration of buildings due to earthquakes. They can work as high performance energy dissipation devices. The oil-damper developed in this study can demonstrate damping performance even to small vibration. Therefore, it is not only effective to earthquakes, but also to strong winds or traffic vibrations. This paper explains the concept of the development, the design method, the experiments, the analytical model, and the calculation algorithm.

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Recently Oil Damper Vibration Control System has been applied to buildings more popularly than before. High damping force of this system not only supplies safety against earthquake but also does favor favorable to environment. Oil damper is connected with braces in series and installed through pins to the building structure. This insures freedom of influence to the building structure, leading to easy installation and removal.

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The objective of this study is to propose two passive control systems for reducing seismic response and damage of wood houses. Various wood-frame joints are experimented, and selection/design criteria for metal joint details are determined. Velocity-dependent as well as deformation-dependent dampers are developed. Simplified methods to design different damper types are proposed. Design of the joints, dampers are validated by conducting dynamic cyclic loading tests for the passively controlled full-size wood-frame specimens.

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A simplified method to estimate the peak relative displacement between two inelastic structures is proposed by considering their vibration phase and time lag of their base motions. Peak differential base displacement is obtained from the difference between displacement time histories of the two remotely located bases. Peak differential structure displacement, defined as the peak difference between displacements of inelastic structures measured from the respective bases, is estimated by the extended spectral difference (SPD) rule and elastic response spectrum, without conducting time-history analysis of the structures. The extended rule considers inelastic vibration phase between the two structures that is affected by structural properties, ductility demands, and time lag of base motions. Thus-obtained two differential displacements are combined to estimate the peak relative displacement, and its accuracy is validated using numerous code-compatible building pairs, 33 earthquakes, and a number of presumed time lag scenarios. Using the method, reasonable time lag magnitude and its effect are discussed. The method is believed to be the most efficient among those available to-date.

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In this paper, an optimum design problem of a base-isolated building as a numerical model of the design method which is commonly used in practice is formulated, and is compared with the optimum design method proposed by the authors. Inequalities between the solutions given by two different optimum design methods are shown, and illustrate the characteristics of these design methods.

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Shaking table tests are conducted to investigate an influence of input wave forms and these maximum acceleration levels on lateral ground force acting on a pile, namely, subgrade reaction in liquefied soil. It is shown that (1) The subgrade reaction mainly acts on a pile as a reaction force before soil liquefaction, and as an external force during soil liquefaction; (2) The pile stresses and displacement under the Port Island wave are larger than those under the Rinkai wave after soil liquefaction; (3) The maximum total subgrade reaction and the maximum inertia force of building act on the pile with a phase delay.

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Passive control schemes to mitigate seismic damage of wood houses are discussed. Extensive shaking table tests are conducted for various full-size wood-frame specimens of either conventional wood frame or proposed passively controlled frame that utilizes deformation-dependent dampers. Performance of specimens is discussed by referring to story drifts, accelerations, base shear forces, damper deformations and forces, and connection deformations. Dynamic properties of the structures such as equivalent periods and damping ratios are also discussed. Test results are compared with the prediction made by the simplified rule based on the dynamic properties and response spectra.

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The lateral load carrying mechanism of Japanese traditional mud walls has been observed by the experiments without initial shear failure. It is clearly shown that the mechanism mainly consists of the following four elements: 1) Compressive vertical pressure force between soil wall and beam or sill at all corners, 2) Compressive vertical pressure force between soil wall and embedded horizontal wooden batten 'Nuki', 3) Shear force between beam-column frame and bamboo member 'Mawatashi', and 4) Moment resistance force at the joints of beam or sill and column. This paper also reports the independent behavior of each componential specimen, which is devised to produce the resistant force of the four elements mentioned above. It is finally shown that the assumption of this load carrying mechanism was satisfactory verified through comparing the tested initial stiffness and resistance force of mud walls with the evaluated ones by the sum of four componential element test results. Also it becomes clear that not only material properties but also construction skill affect the behavior of the elements.

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A new seismic retrofitting method by using a circular hollow section (CHS) bracing is proposed for existing R/C frames with spandrels. In the proposed method, a reinforcing frame composed of an H-section peripheral frame and pin-ended CHS bracings is placed on the outer surface of an R/C frame and connected to it with mechanical anchors and high strength mortar. Experimental studies were carried out to evaluate the reinforcing effect. A tube-in-tube brace, which is restrained not to buckle by the outer tube, are applied as a reinforcing brace. For comparison, H-section braces are also applied. All the specimens are 1/3-scale models for one story-one bay substructure frame of an R/C building, and the columns are brittle. In the experiment, the horizontal loads were cyclically applied to specimens under a constant vertical load. Through the experimental results and analytical results, effectiveness of the proposed method is discussed. Predicted load-displacement relationships of the reinforced R/C frames are reasonably agreed with the experimental ones.

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In this paper, an energy absorption wall with multi-stage destructive mechanism is experimentally studied. The wall is made by filling the gap between the alignment of energy absorption members. The energy absorption members are made by using hybrid fiber reinforced cementitious composites and reinforcement. In the test, shear test specimens are made with two energy absorption members, and cyclic load is applied. The results show that the energy absorption wall clearly gives the multi-stage destructive mechanism and also gives the ductile hysteresis curve. It is concluded that the energy absorption wall is applicable to the structural control.

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The evaluation method of experimental result of 1-D shaking table test is advanced to 2-D shaking table test. In this method, the transference of energy from shaking table to the specimen is focused. Energy applied to the shaking table is calculated by the output information of shaking table. In this study, a series of excitation of shaking table without specimen is carried out as a primary test. This primary excitation intends to clarify the coefficient of friction and the damping factor of actuator. Following the primary excitation, shaking table test of 3-D steel frame model is carried out. From the experimental result of shaking table test, evaluation method of experimental result is verified.

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In this paper, an alternative vibration control system for long-lived steel buildings has been proposed and the static cyclic loading tests have been performed. The effects of the shape and size of the bending failure beam as a damper on the elastic-plastic hysteretic performance have been discussed. The optical fiber Bragg grating sensors have been installed on the surface of the beam and the optical power spectra as well as the strain quantities using their outputs have successfully been measured in detail. It has been shown that the spectra change from sharp one-peak type to multi-peak one due to steel yielding. The characteristics would be useful for assessing the damage level after large earthquake.

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Effects of stress-strain curves on limit width-to-thickness ratios of steel plates and limit diameter-to-thickness ratios of steel circular cylinders were investigated by means of a Finite Element Method. Preceding the parametric study, the applicability of the FEM was established by achieving a good agreement between FEM and stub-column test of stainless steel plates and cylinders. It was found that the limit ratios are apparently affected by the shapes of stress-strain curves in such a way that the C_1-coefficient for plates and C_2-coefficient for cylinders are strongly positive-correlated with the tangent modulus and secant modulus at the yield stress of the material. Noticing that the limit width-to-thickness ratio of plates is represented by [numerical formula] and the limit diameter-to-thickness ratio of cylinders is represented by C_2/σ_y, a larger offset for determining the yield stress σ_y gives smaller values for C_1 and C_2.

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In this paper, a newly external diaphragm connection detail is proposed for steel beam to concrete-filled square steel tube column moment connection. This connection detail has divided diaphragms to reduce welding for simplifying the steelwork for conventional external diaphragm connection detail. The local elasto-plastic behavior for the connection detail is same as that for the conventional connection detail from tensile tests. An analytical model is proposed for predicting the load-displacement relation of such local connections. This model is developed by superposing the strength of diaphragm on the load-displacement relations for a tube flange. The tube flange is modeled as a grid beam with a tetra-linear load-displacement relation. The analytical method is found to agree approximately with experimental results up to large deformations.

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An analytical solution is presented to predict the sloshing response of a cylindrical liquid-storage tank with floating roof under earthquake excitation. The containing liquid is assumed to be invicid, incompressible and irrotational, while the floating roof be an isotropic elastic plate with uniform stiffness and mass. The dynamic interaction between the floating roof and the liquid is taken into account exactly within the framework of linear potential flow theory. By employing the Fourier-Bessel expansion technique in cylindrical coordinates the solution is derived in an explicit form, which is convenient for parametric understanding of the sloshing behavior and preliminary study in the early design stage. Numerical results are also provided to investigate the effect of the stiffness and mass of the floating roof on the sloshing response.

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Elastic response of large floating structures subjected to wind waves is amplified when wet mode frequencies are located in the central region of wave spectrum. Another important aspect of elastic response amplification is the global or local coincidence of wet mode shapes with the distribution profile of hydrodynamic pressure acting on the bottom surface of floating structure. For the purpose of evaluating the latter effect quantitatively, the hydroelastic response of a large circular floating structure is formulated by wet mode superposition in the wave number domain. Numerical results are presented to illustrate the amplification mechanism of global and local deformation of large floating structures. Moreover, the way of controlling wet mode shapes is proposed by adjusting moorings stiffness totally or partially to reduce the overall elastic response.

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