Using polypropylene fibers treated hydrophilically for cementitious components by extrusion moulding, it has been confirmed that flexural behaviors of these components are improved. This paper deals with geometrical effects of this fiber from the viewpoints of improving the flexural behaviors of cementitious components on the basis of two series of experiments. The following items are clarified; l) Regardless of the geometrical effects of fibers, first cracked flexural strength and effective water cement ratio had a unique linear relation. 2) First cracked flexural strength could be predicted in general by extruding pressure. This knowledge was utilizable in the quality control in manufacture. 3) The relation between first cracked flexural strength and surface dry density was represented as a unique curve for every kind of fibers.

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Flexural strength and densification of cementitious materials produced by extrusion moulding were experimentally examined especially focused on the cases of using visco additives (Methyl cellulose) with various values of viscosity. Densification effects under a set of extrusion moulding experiments were measured in the various stages of processes. Total voids to cement ratio is clarified to be related to flexural strength independent of the viscosity of visco additives even if in the various cases of using visco additives. Medium one was the most appropriate for obtaining high flexural strength.

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Corrosion of steel in uncarbonated and carbonated concrete was investigated by accelerated exposure tests. The parameters of the specimens were crack width, cover thickness and water to cement ratio of concrete. The results indicate that : (1) The corrosion area ratio and the weight loss of steel in uncarbonated concrete increased as the crack width and the water to cement ratio increased; (2) The existance of a crack strongly affected steel corrosion in carbonated concrete, though the effect of crack width became weaker as the degree of carbonation increased, ultimately disappearing; (3) Though the weight loss of steel in carbonated concrete was larger than that in uncarbonated concrete specimens, the corrosion current value was conversely lower in carbonated specimens. It is thought that carbonation of concrete caused microcell corrosion to became larger than macrocell corrosion. As the water to cement ratio increased, this tendency became more evident; (4) As the corrosion area ratio increased, the macrocell ratio, i.e., the percentage of macracell corrosion to the total corrosion of steel, decreased.

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Although the mud wall has been used in many buildings from old time, the material property is still unclear. The quality of "KABETSUCHI", which is the main material of the mud wall, depends on the place of production because it is nature material. The purpose of the experiment is to estimate exactly the quality about mixing, workability, shape of test piece, compactness, and strength test of the KABETSUCHI.

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Shop-welding robots have been already lined as main production tools in the automobile industry. And recently the employment of welding robots is increasing in the small factories of the steel fabricators. But the development of field-welding robots is very much behind that of shop-welding robots, because being a precision machine, field-welding robots must be employed in disarranged circumstance of the building site, and column-to-column welding joints are full penetration single bevel grooves and require a high level of welding techniques together with many new knowledge in robotic welding. For example, when a pair of robots runs symmetrically on the same rail for welding facing sides of a column to minimize welding shrinkage, a difference of welding shrinkage occurs between preceding and following welding. This paper describes the best conditions of groove shape to get satisfactory welding quality based on a series of experiment on welding shrinkage and opening under backing plate.

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In reliability-based limit state design, the performance level of a structure can be controlled by differentiating load and resistance factors. In order to take fully the advantage, Draft Recommendation of Limit State Design by AIJ proposes a practical method for evaluating the factors. This paper investigates its accuracy and applicability using numerical examples. It was found that a large error could be observed, depending on the statistical characteristics of load intensities, due to mainly improper approximation of non-lognormal random variable to lognormal. An improved method for the approximation is proposed taking the target reliability level into account.

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The purpose of this paper is to investigate the dynamic characteristics of multi-story wooden Pagoda, based on microtremor measurements and man-excited vibration tests. According to the results of the field survey, a strong correlation is observed between natural period and height of wooden pagodas. The natural period(T) is related to height(H) of wooden pagodas by the following equation; T=0.035H. However, it is difficult to find a direct relationship between the damping factor and height of pagodas. The damping factors are observed in a range of 2〜6%, regardless of height.

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It is shown that the wave propagation can be explained on the basis of the simple equation, which expresses the relationship between the phase differences and the delay time of a wave. Since the phase differences of a pulse are uniform, the rupture process of a source region and the wave propagation, including directivity, of an earthquake can be understood in terms of the dispersion with respect to the phase differences of pulses radiated from a sequence of point sources in a fault plane considering the onset time, the location of each point and the dispersion of the apparent phase velocity. This idea is verified by analyzing recorded earthquake motions. It is concluded that the source and propagation characteristics of earthquakes are reflected in the information of phase characteristics.

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We simulate strong ground motions during the 1945 Mikawa earthquake with the JMA magnitude 6.8 based on a characterized source model and the hybrid simulation technique. Relative locations of two asperities on the fault plane are determined following the inverted source model by Kikuchi et al.(2001). Each asperity area is estimated based on the self-similar scaling relationships of seismic moment versus asperity areas and slips by Somerville et al.(1999). Broad-band strong ground motions are calculated by the 3-D finite difference method and the stochastic Green's function method. Finally, the distribution of the instrumental seismic intensity calculated from the synthetic acceleration motions is compared with the distribution of the seismic intensity estimated from the collapse ratio of wooden houses by Iida(1985).

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This paper describes a simple semi-active control algorithm in which the Magneto-Rheological fluid (MR) damper's hysteresis shape is controlled. The proposed method aims at reducing a displacement without increasing an acceleration response. The first part of this paper presents the basic properties of the proposed method obtained by analytical and numerical means using a S-DOF system. Next, it describes a series of seismic response analyses carried out in order to verify the applicability of the proposed method to base-isolated structures, It was confirmed that the proposed method is effective in improving the performance of the base-isolated structure.

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The influence of P-Δ effect on structural performance of lumped mass models subjected to earthquakes was discussed. While the stability factor θ (the ratio of the equivalent stiffness to the elastic stiffness of structures) is a general parameter which expresses P-Δ effect, it had been made clear that the stability ratio τ which conveys the information of the critical deformation responses is more appropriate than θ as a parameter to express P-Δ effect. τ is the ratio of the actual θ to θ in case when structures collapse just at the end of earthquake if the plastic energy consumption is one-sided. Numerical analyses of earthquake responses of lumped mass models were performed parametrically. and the results are summarized as follows; a)Increase of damage of a structure by P-Δ effect can be expressed in terms of τ. b)The maximum plastic deformation of a structure under the influence of P-Δ effect can be expressed in terms of τ. Empirical formula for average deformation response were presented. d)As a value corresponds to the collapse of frames, the critical stability ratio was presented.

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The nonstationary ground motions are assumed to be expressed as the product of an envelope function representing the temporal amplitude modulation and another function representing the frequency content of a stationay random process. In the previous investigation due to the present author, the envelope functions of nonstationary ground motions were fixed and the critical frequency contents were found. In contrast to the previous studies, the critical envelope functions are investigated here with the frequency contents fixed to the critical one found in the previous study. It is shown that the order interchange of the double maximization procedure with respect to time and to the envelope function can be a powerful solution algorithm for finding the critical envelope function.

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It is difficult to estimate actual stiffness and mass of a structure, although the ratio of them can be easily determined from resonant frequencies. Since we have almost no direct observation of actual stiffness or mass, we try to estimate both the actual mass and stiffness of a reinforced concrete building through an innovative approach. The method of this study is based on the resonant frequency shift. First, we identify modal parameters (resonant frequency and damping factor) by the curve fitting in frequency domain for both original condition and shifted condition due to an added mass with known amount. We estimate three-dimensional vibration characteristics by mode separation based on a rigid body assumption. Then we estimate actual stiffness and mass as a lumped mass vibration model to fit the resonant frequencies for both conditions using eigenvalue analysis. We obtain the mass to be 1.44 times larger than the design value and the stiffness to be 1.36 or 2.60 times of the frame estimate. These estimated stiffnesses are within the range of standard initial base-shear coefficient determined by damage statistics in Kobe.

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In previous studies we have established a set of dynamic models of reinforced concrete (RC) buildings and wooden houses for damage evaluation based on the damage statistics in Kobe surveyed after the 1995 Hyogo-ken Nanbu earthquake and nonlinear response analyses for synthetic waveforms simulated by Matsushima and Kawase (2000). In this paper, we proceed to construct a set of dynamic models of steel buildings for damage evaluation. In the process of establishing models we found that strengths of steel buildings are not so much different from those considered in the building code. This implies that the strengths of steel buildings are not influenced strongly by other factors not considered in design such as non-structural partitioning walls. Damage ratio distributions derived from established models show similar pattern to the observed ones though calculated damage ratios are distributed wider than the observed. By using steel building models established here with the models for reinforced concrete buildings and wooden houses already established, we can predict the whole picture of urban seismic disasters.

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This paper deals with the elastic analysis of reinforced concrete beams with various cross-sectional types considering bond-slip of reinforcement and the effect of transverse shear deformation based on the Timoshenko beam theory. The effect of transverse shear deformation that beam can be evaluated by using the transverse shear strain energy that is calculated by the distributions of transverse shear stress along the cross section. In this paper, first, a potential energy functional is derived. Then, a finite element formulation of the problem is implemented. And in order to examine the use of presented procedure, some numerical examples are solved.

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An earthquake-proof pile composed with a main pile and a short outer sheath pile has been proposed by the authors. This outer sheath pile is isolated from the main pile. In this study, a roller and a pin mechanism are inserted between the main pile and the outer sheath pile in the tip position of the latter pile, in order to secure clearance between both piles during construction and also in an earthquake. This paper presents the calculation result of the earthquake-proof pile, which is composed with a PHC-pile (main pile) and a steel pile (outer pile). These results suggest that the bending moment in the main pile and the horizontal deformation of the earthquake-proof pile with a roller and a pin coupling could be decreased remarkably in comparison with an isolated main pile, even if the outer sheath pile length is so short as 2.5m.

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This paper describes the behavior of pile raft foundations obtained from in-situ horizontal loading tests carried on practical but downsized foundation models. Three foundation types, the raft foundation, the pile foundation and the piled raft foundation were tested to clear the behavior of piled raft foundations under horizontal load. Each foundation consists of a concrete block of 2m square with different height, and four steel pipe piles of 48.6mm in diameter in cases of the pile foundation and piled raft foundation. The test results indicate following observations. The final resistance of the piled raft foundation is larger than the summation of those of the raft foundation and the pile foundation. The bending moment of the piles in the piled raft foundation is smaller than that in the pile foundation at same horizontal displacements. In the piled raft foundation, the horizontal load is mainly transferred to the ground through the raft at the beginning of the loading, and is supported more by the piles as the horizontal displacement increases.

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Large-scale shaking table tests are conducted to investigate phase difference between the inertial force of the super-structure and total earth pressure acting on the footing. It is shown that (1) The total earth pressure before liquefaction tends to be out of phase by 180 degrees with the inertial force, (2) The total earth pressure after liquefaction tends to be in phase with the inertial force, (3) Phase difference between the inertial force and total earth pressure can be estimated by considering the natural period of the super-structure, the predominant period of the ground, the ground displacement and the footing displacement.

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The coefficient of subgrade reaction of pile during soil liquefaction is back-calculated based on large shaking table tests. The effects of soil density. relative displacement and pore water pressure ratio on the p-y relation between subgrade reaction and relative displacement are examined, and a simplified procedure to estimate time history of p-y relation is presented The p-y relations computed by the proposed method are in good agreement with the experimental ones. irrespective of depth, level of input motion and soil density, indicating that the proposed method is promising for estimating p-y relations during soil liquefaction.

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Thin membrane has small flexural stiffness and will wrinkle under compression stress. The wrinkling is not only effecting the appearance of a building but might also become the reason of failure under the repetitive deformation. In this paper, an experiment research of rectangular tensioned membrane under one-directional tensile force has been introduced. The occurrence of wrinkling and the influence of material character, width-to-length ratio and tensile force have been discussed. The wrinkling performances have been analysed by using Fourier Spectral Analysis. Finite Element Method has been used for the 2-dimension stress analysis of the experimental model, and this was compared with the experiment result.

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The purpose of this paper is to present the method to get a lower bound intensity of harmonic excitation easily, in which geometric non-linearity does not appear, for arch structures subjected to horizontal harmonic excitations. Ordinally, to get the intensity, many numerical calculations are executed. But this present method does not need such calculations. The intensity value can be predicted by coefficients of geometrical non-linear governing equations of the system. This paper shows the way to make the governing equations and the equation of lower bound intensity.

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Hybrid single-layer lattice shell using supplementary parts is the rectangular grid shell stiffened by parts. The truss system that is used as the parts, is effective for improving bending stiffness of the low-rise shell. In the paper, the procedure to decide the arrangements of parts to control stress of the lattice members is proposed. This procedure gives the arrangements, which improve the yield load of the structure effectively. The results of nonlinear stress analysis show that the combination of this procedure and the other procedure, which was proposed already and improve the buckling load, increase effectively both the yield load and the buckling load.

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System truss, of which structure is used as shelters in disasters, is required to fill high earthquake resistant performance. The concept of damage-controlled structure that reduces seismic response is effective to meet the requirement. Required performance of flat system truss as damage-controlled structure is; independence of vertical load and lateral load, reduction of response and damage cost. Here, we proposed structural types of axial yield hysteretic dampers arranged for flat system truss as damage-controlled structure, and did evaluations about required performance of these structural types. Our verification also indicates that the result applies to the large span structures.

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The purpose of this study is to propose a prediction method for the collapse mode and its relevant bearing capacity of a timber space frame subjected to vertical load such as excessive snow load. Experimental and analytical studies for the 1/10 scale basic timber structural models were carried out in order to investigate the mode type and its maximum vertical load when some type of collapse mode occured. As a result, the predicted results showed good agreement with the experimental ones when the spring stiffnesses of connections were estimated appropriately through the actual loading test of connection models.

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The uniform truss mechanism is widely accepted as a shear transfer mechanism reinforced concrete members. However, the uniform truss action cannot be expected when the bond stress distribution is not constant along longitudinal bars. A test method, in which only the truss action takes place, is developed and conducted to investigate the truss actions under various bond contributions. Based on the experiments and analysis, following findings have been obtained; 1) The bond stress distribution depends on the axial compression force, the amount of shear reinforcement and loading conditions. 2) The analysis using the composite truss model composed of regular and fan-shape trusses can predict the experimental results.

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A seismic evaluation method for existing reinforced concrete buildings retrofitted by energy absorbing devices such as braces and stud columns with a damper is proposed in this paper. The proposed method is a static procedure to calculate the seismic index, I_S, for the buildings, which is an index to judge whether existing buildings and those retrofitted by conventional repair techniques are safe for the assumed earthquake load in the Building Standard Law of Japan. For three one-bay-one-story reinforced concrete frames with an energy absorbing device for which shaking table tests have been conducted, the I_S values calculated by the proposed method is compared with those assumed from the test results in order to examine the validity.

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RC column specimens generally have stiff stubs at their ends. But they differ from actual columns influenced by beams and slabs in boundary conditions. In this paper, Specimens with boundary conditions of actual structure or stiff stub were made and tested. The conclusions are as follows. The bending strength and ductility of internal columns is equal even if they have different boundary conditions. External columns with boundary condition of actual structure is equal to specimen with stiff stub in deformability, but inferior to that in bending strength. Boundary conditions of column specimens affect plastic hinge zone and its curvature.

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This paper presents the results of the experimental tests completed to investigate the strength and the deformation capacity of Prestressed Reinforced Concrete pile (i.e., partially prestressed concrete pile) with shear failure. Eight specimens were tested; four with shear span to depth ratio of 1.5 and four with shear span to depth ratio of 2.0. The hollow space of each pile was filled with normal-strength concrete. The specimens modeled as the pile head were subjected to reverse cyclic loading under sustained axial load. The conclusions of this study are : (1) the deformation capacities of PRC piles with the different parameters (amount of lateral reinforcement and shear span to depth ratio) can be evaluated using the shear strength to flexural strength ratios, (2) PRC piles with the shear strength to flexural strength ratios more than 1.05 have the ultimate deformation angles more than 0.034rad.

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The objective of the present study is to investigate elasto-plastic behavior of the ductile vinylon fiber reinforced mortar shear walls by means of the finite element procedure, which incorporated the material models formulated on the basis of the fracture mechanics concept. The variables for the test and analysis include the type of concrete and mortar in the shear wall panels. The following findings were obtained through this study : 1) The up-grading and damage control effects of the ductile vinylon fiber reinforced mortar were veirfied by both the test and analysis. 2) The FE analysis procedure can simulate elasto-plastic shear behavior of the ductile vinylon fiber reinforced mortar shear walls.

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This paper presents a research on the strength of the bolted beam-to-column connection which makes the most use of panel zone yielding of the wide-flange column as energy dissipating elements for earthquake resistant design. Major findings are summarized as follows. (1) The collapse strength of a column flange subjected to the out-of-plane force due to the tensile bolted joint is obtained by applying the yield line theory and its validity is experimentally confirmed. (2) The collapse mechanisms which occur at a split-tee type or a double-angle type of bolted beam-to-column connection are enumerated and the collapse strength of each mechanism is formulated. (3) Some examples of the connection design are illustrated and the advantage of the double-angle type connection is revealed.

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The relationship between true stress and true strain of structural steel was simply modeled considering the Bauschinger effect. This hysteresis model is composed of skeleton curve based on the material test result, Bauschinger part modeled as a function of the cumulative strain in the skeleton curve and elasticity unloading part. The analytical result of the beam which applied this hysteresis model was compared with experimental result. The analytical result and the experimental result showed the good correspondence in not only load deformation relationship but also deformation of skeleton curve as an index to the plastic deformation capacity of member, moment-curvature relationship and hysteresis of strain. Though the hysteresis model is simple, it is enough effective in order to analyze the behavior of steel member in the plastic range.

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In the past, in order to predict the ignition time, the use of various physical properties was required. However, almost all physical properties of wood have a correlation with density. Therefore, the thermal physical property of wood (in a model of predicting ignition time) is replaced by the function of density, so that the ignition time of wood can be expressed in terms of density, external heating and two constants. Cone calorimeter test was performed with 7 kinds of wood, after which the constants decided. Consequently, the ignition time of wood can be predicted from the density and external heating.

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This paper is concemed with the structural damage detection of the unit-linked floating structure model by coupled free vibration analysis, in combination with filtering algorithm. The structural damage analysis is generally formulated as an inverse problem. The formulated inverse problem must be analyzed under the consideration of stochastic properties on the response of structural system. The filtering algorithms have been known as one of the inverse analysis method. In this study, algorithm based on parametric projection filter is employed as new analytical algorithm on the structural damage identification. The coupled natural frequencies used as the observations and stochastic properties of system responses adopted the data obtained by experimental modal analysis. From identification results, adaptability and characteristics of the algorithm based on parametric projection filter are discussed on the inverse analysis of the fluid-structure interaction coupled system.

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