For the sake of finding the factors which influence the mechanical performance on short fiber reinforced cementitious composites, a parametric study was experimentally carried out. Nine parameters on fiber and four parameters on mortar matrix were varied. Then the experimental results on bend and compression tests were assessed for nine parameters concerning the mechanical performance indexes such as the maximum strength, deformability and several toughness indexes. Finally these results were analyzed by a multi regression analysis to formulate design criteria for the each mechanical performance index as a function of some selected parameters on fiber and mortar matrix.

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In this study, the prediction model of carbonation progress rate of concrete using fly ash as an addition is developed, in which the reduction of not only the diffusion rate of CO_2 but also the amount of Ca(OH)_2 by pozzolanic reaction of fly ash. The model is based on the diffusions of CO_2 and its reaction with Ca(OH)_2, and considers the coexistence of CaCO_3 with Ca(OH)_2 in carbonation progressing region. The model can also explain the characteristics of carbonation resistance of concrete that the matrix is densified due to carbonation. The prediction by the model agreed well the experimental data in which the concrete using fly ash showed the higher rate at carbonation in early age and the lower rate in long-term age than the concrete without fly ash. Consequently the model can predict the rate of carbonation of concrete exposed in the atmosphere regardless of the water-to-cement ratio, the amount of the content of fly ash, etc.

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Influence of aggregate concentration on gas diffusion coefficient in concrete with various water-cement ratios was obtained under the various relative humidities. The relationships between effective diffusion coefficient and relative humidity in mortar or concrete had construct of three provinces, similar to hardened cement paste. The effective diffusion coefficients were small affected by aggregate concentrations, except for under the absolute dry condition. Using to these results, the gas diffusivity in transition zone was discussed by the theory of composite material with hardened cement paste, aggregate and transition zone.

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This report describes an experiment on the mechanical properties of high-strength concrete ( water binder ratio from 20% to 50% ) subjected to high-temperature heating ( from 100 to 600 ℃ ) assuming a fire, and discusses the results. The following conclusions were obtained. l) Concrete with low water binder ratio ( 20%, 25% ) mixed with vinylon fiber at 0.5%/vol. can prevent spalling. 2) The retained ratio of compressive strength and static modulus of elasticity after heating to that before heating of concrete with low water binder ratio, is higher than of normal-strength concrete provided spalling does not occure. 3) The retained ratio of static modulus of elasticity in the high-strength concrete subjected to 600℃ heating reduces to about 10% of that before heating as well as in the normal-strength concrete.

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Bingham's model is generally used as a rheological model for fresh concrete. However, Bingham's model for homogeneous materials is not always adequate to express the behavior of composite material such as fresh concrete. In this study, the numerical analysis of the flow of fresh mortar is carried out by visco-plastic finite element method (VFEM) using the shear strain dependent viscoplastic model. It is shown that the analytical results are in good agreement with the experimental ones, and that this model is appropriate. Furthermore, the mechanism of blockage of fresh mortar is discussed analytically.

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In this study, the fracture process of strain softening and hardening material which has the crack dispersion and localization characteristics was studied. Numerical analysis method to calculate the load displacement relationship of the member which has multiple cracking subjected to the bending was proposed based on the fracture mechanics consideration. Bending tests of the fiber reinforced light-weight concrete panel were performed. Influences of the fiber content and the air content on the mechanical properties and on the crack dispersing effect were cleared. Especially, the fiber reinforced light-weight concrete containing air showed high crack dispersion under the bending condition. Tension softening diagram of fiber reinforced light-weight concrete which can be used as a constitutive law for the numerical analysis were evaluated by the data of a load - crack mouth opening displacement (CMOD) relationships obtained by the wedge splitting test. The analysis results of the bending tests agreed well with the test results.

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By using the various steels (SS400, SR295, D6 S35C, H6 KHT80, F6 SCM4, KPC H4, G4 1041 and E6 SCM4), the tensile fracture test after compressive loading (C+TF) is carried out on cylindrical specimens (G.L.=2.5D=28:25mm). As the results of the tests, it becomes clear that the elongation by the TF test is larger than the elongation by the monotonous tensile facture test. The cumulated damage energy, which dissipated at the last tensile fracture is almost the same with the cumulated damage energy which are defined as dissipated upper the loading value of P_y/2 under monotonous tensile fracture test. From the result of the super low cycle fatigue fracture tests under definite constant deformation amplitudes, it becomes clear that the D6 S35C material consumue the cumulated damage energy very much. On the extremely low cycle fatigue fracture tests, the ratio of cumulated damage energy for cumulated damage strain under the definite constant deformation amplitude test is from 1.1 to l.4 times as much as the ratio of damage energy for damage strain under the monotonous tensile fracture test.

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A model for estimating flexural strength was proposed in this paper. The model traces destructive mechanisms conscientiously. Therefore it can be applied for the several kinds of glulams that consist of some dimensions, stress conditions and woods. The model means that a lamina of glulam is divided into minute elements in the direction of length and minute elements that have each strength according to knots, finger-joint or clear wood. The element disappears when the element reaches its strength against the applied load. The concentration of stress and progress of cracks can be traced by removing minute elements in this model. The maximum flexural strength of a glulam beam is calculated as the minimum moment among the sums of moments that all elements resist on the same dimension. For confirming agreement of this model, Monte Carlo simulations were carried out. The estimated values using this model agreed well with several experimental data.

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This paper presents a simple strength simulation system newly investigated by the authors for mass concrete structures in cold weather. The system greatly simplifies the strength simulation of mass concrete structures. The aim of the research leading to this system was to create a simple and rational method of accurately predicting and determining certain properties of concrete in actual structures without resorting to full-scale modeling or complicated numerical analysis. Experimental test on mass concrete structures in cold weather was carried out in Sapporo and analytical study by a computer was also carried out to verify system's effectiveness. The good results obtained in the experimental test and in the analytical study established efficiency in predicting the strength of mass concrete structures in cold weather.

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Performance of drainage systems of glass rods piled-up was studied. The effects of the gap between rods, number of layers, and inclination and length of systems on their drainage ability were first experimentally studied. It was found out that good performance in drainage was observed at the condition of continuous water flow over glass rods, and there was the suitable gap between rods for it. Drainage ability also improved according to increase of number of layers and inclination of the systems. The simulation program that expressed the behavior of water in the systems was furthermore developed, and the drainage ability of the systems was quantitatively estimated.

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The irregularity of tiles is recognized by the joint width variation, and the luminance contrast and the shadow occurred by the unevenness . We investigated about the unevenness, in addition to the joint width variation in previous reports. Then, we measured positions, luminance, and shadow size of tiles of sample walls, examined relations with the psychological scale relating to the irregularity, and got basic quantitative values of the factor of the joint width variation 'Wj', the luminance contrast 'Lc' and the shadow effect 'Se'. Finally, by compounding them, we established 'CI as the quantitative value corresponding to the conspicuousness of irregularity.

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A new method of simulating turbulent flows is proposed, which works like an LES method when the grid size is small enough to resolve time-dependent large eddies and reduces to a conventional Reynolds-avenged Navier-Stokes equation method when the grid size becomes large. The transition is achieved by introducing the switch-over function applied to the eddy viscosity coefficient that is determined by a method similar to existing two-equation models. The method has been applied to flows over smooth topography with or without flow separation. The results give detailed time-accurate flow field that have not been possible by a conventional unsteady RANS techniques and the time-averaged results agree well with experimental results

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This paper discusses the potential of Large-eddy simulation for predicting the turbulent characteristics in a spatially developed turbulent boundary layer over a rough ground surface. Lund et al. proposed the method using quasi periodic boundary condition for smooth-wall turbulent boundary layer. Here we modify this method so that it could be applied to the flow over a rough ground surface. Roughness elements are arrayed on the ground to match the mean velocity profile with power law with exponent a = 0.25. The roughness length, the roughness displacement and the turbulence intensities are in good agreement with experimental data. The ratios of integral scales of turbulence almost conform to previous investigations. However, we necessarily can not simulate all the turbulent quantities, so the complete periodic boundary condition is required for elimination of unfavorable peak in the spectra of a velocity fluctuation.

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Scenario earthquakes are significant for not only evaluation of seismic loss in large urban areas, but also pricing of insurance linked securities for earthquake risk. This paper combines active fault data and historical seismic records to prepare the seismic sources for scenario earthquakes with their occurrence interval. The seismic sources for randomly distributed intraplate earthquakes without surface faults are also prepared so that they can be treated as scenario earthquakes. Using these seismic sources, I evaluate a maximum credible acceleration map in overall Japan due to scenario earthquakes.

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The authors propose a micro-vibration isolation system composed of springs and viscous dampers. Application of isolation systems in highly seismic areas like Japan requires confirmation of seismic safety as well as isolation capability. The study on the seismic safety of this system was described in a previous paper. This paper deals with the isolation capability of this system to micro vibration. A series of excitation tests using an exciter, a steel ball dropping and a running truck are carried out. Finite element analyses by a dynamic substructure method is conducted. Through these tests and the analyses, the isolation capability of this system is clarified, and the accuracy of the dynamic substructure method for predicting vibration transmission loss is validated.

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An algorithm based on Semi-Definite Programming (SDP) is proposed for the truss topology optimization problem for specified linear buckling load factor, and optimal topologies of trusses are computed by using the Semi-Definite Programming Algorithm (SDPA). It is well known that optimizing structures for specified buckling load factor is difficult because of non-differentiability of the buckling load factor for the case of multimodal solutions. It is shown, in the examples, that the proposed algorithm is applicable to multimodal cases, and an optimal topology with five-fold buckling load factors is found without any difficulty.

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The authors presented a proportioning method for member sections of single layer reticulated domes in the previous papers based on a second-order elastic analysis. In the first part of the present paper, a method complementary to the above method is proposed based on linear buckling stress obtained from linear buckling analysis, being more familiar than the second-order elastic analysis. The proportioning method based on linear buckling stress is verified through elasto-plastic simulation for roller supported single layer reticulated dome. The second part of the present paper discusses buckling stresses and buckling loads of single layer reticulated domes under non-uniform loadings. The usefulness of this proportioning method under non-uniform loadings is discussed and verified through elasto-plastic simulation for roller supported single layer reticulated domes.

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In order to comprehend the elasto-plastic behavior of RC box type shear wall subjected to diagonal load, reversed cyclic loading test has been carried out using 8 test specimens where loading angles and shear span ratio were set as test parameters. From the test results, it was observed that loading angles affected the maximum load and overall deformation, and they tended to be larger as the loading angle was close to 45 degree. Based on the conventional methodology to calculate restoring force characteristics of nuclear power buildings, we proposed an evaluation method taking into account the effect of diagonal loading for shear and bending components. Comparing with calculated results using proposed method and the test results, calculated results coincided well with the test results, and applicability of the proposed method was confirmed.

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The purpose of this study is to determine quantitatively the geometrical characteristics of the cracked surface in light-weight concrete and normal-weight concrete by obtaining highly precise data. Light-weight concrete is composed of artificial light-weight aggregate of expansible shale, with a weight of unit volume of between 1.1 and 1.6 t/m^3 and a compressive strength between 24 and 60 N/mm^2. The cracked surface was analyzed by a laser measuring instrument with a CCD (Charge Coupled Device) transducer. The following conclusions can be drawn from this study: 1) The complex asperity of the cracked surface can be represented as assembly of infinitely small pieces defined as contact surface, 2) The area of contact surface in light-weight concrete and normal-weight concrete can be calculated as the product of the contact-angle probability density, the effective ratio of contact-roughness and the entire surface area per unit crack plane.

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Reports the results of an experimental investigation carried out on strengthening and repairing of shear failure type reinforced concrete (R/C) columns by using ferrocement jackets. Four identical original R/C columns were constructed. Two original columns were tested to their failure, repaired and strengthened with ferrocement jacket, and retested. The other two original columns were tested after being strengthened using ferrocement jackets. Unless failure occurred at an earlier stage, all columns were tested under cyclic lateral forces and constant axial load. From the test results it was found that the proposed repairing and strengthening technique is very effective.

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This study presents a method to evaluate the shear strength of multi-story precast concrete structural walls with slip at horizontal joints. An analytical model, which considers the shift from the truss and arch resistance mechanisms to the each story arch mechanism after the horizontal slippage, is idealized. This proposed analytical model assumes that the total shear strength of a multi- story wall is the sum of the shear strength when slip occurs at wall joints and the combined shear resistance provided by arch mechanism in each story after slip. Experimental test results on shear strength and failure mode of 50 multi-story precast concrete structural wall specimens are presented. The proposed model provides safe strength estimates and agreeable results on failure mode.

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Primary factors, which have an influence upon the maximum strength of beam-to-column connections, were investigated based on the test results reported in papers . The relationship between the test conditions and the maximum strength for 263 specimens was studied. It was found that the maximum strength of connections for fast loading and/or in low temperature can be estimated using the same method as that for static loading in room temperature in consideration of a variation in yield point and tensile strength caused by strain rate and/or temperature. The conditions in which the maximum stress of beam flange is nearly equal to or exceeds the tensile strength of coupon tests were investigated.

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The resistance of a structure against an earthquake is related to Its ability to dissipate the seismic input energy. The input energy can be absorbed by plastic deformations of building frame-components such as beams and columns, or by specially prepared members such as hysteretic dampers. The second altemative is very advisable as it can prevent the damage to the main frame. Along this line, two new brace-type hysteretic dampers have been developed recently". The new dampers use steel rods and steel plates with slits as energy absorbing device. This paper presents the results of full scale and real time dynamic shaking tests, conducted for assessing their predicted behavior. On the tests, the brace dampers were installed in an auxiliary testing frame forming a flexible-stiff mixed structure, and stressed up to its collapse. The test results confirmed the expected dynamic,response and proved their high energy absorption capacity.

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In this paper, an experimental method of shaking table test on partial moment resisting steel frames is discussed. This experiment system consists of a Mass, a Spring, a Loading Beam, a Specimen and a Shaking table. The natural period of this system is set at about 0.7-0.8 second which value is nearly the same as middle rise steel buildings. Features of this method show in the follows. This method has a system of proper estimation for the response of partial frame against Real Time Speed Earthquake. This method approximately reproduces an earthquake resisting behavior of the partial frame. It is possible to effectively utilize the performance of small and medium size shaking table.

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Three-dimensional frames consisting of CFT columns and H-shaped beams were tested under a constant axial load on the column, constant beam loads in the minor direction, and altemately repeated beam shear in the major direction simulating the earthquake loading. The specimens were designed for two kinds of failing type; shear failing of the beam-to-column connection panel, and flexural failing of the column. The paper presents the test results, and discusses the hysteretic behavior, the maximum strength and failure mode of each specimen. It is concluded that the panel-failing specimens are generally more stable compared with the column-failing specimens.

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In this paper, analytical and experimental investigations are conducted on the tensile elasto-plastic behavior of new vertical-stiffener-type local connections between steel beams and concrete-filled tubular steel columns. The beam-to-column connection requires no curvature to be formed for welding and shearing steel plates, and it simplifies the steelwork. This paper proposes a new analytical method for predicting the load-displacement relation of such local connections. This method is developed by superposing the load-displacement relations for a tube and a stiffener. The tube is modeled as a grid beam with a tetra-linear load-displacement relation, while the stiffener is modeled as tensile members with a tri-linear load-displacement relation. These analytical methods are found to agree with experimental results up to large deformations.

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A theoretical method is proposed to extrapolate the steel temperature under standard fire tests for various cross sectional areas of steel and insulation thickness. The method utilizes the parameter estimation technique, where the parameter in the lumped heat transfer model is estimated to fit to the steel temperature rise in a standard fire resistance test. By using the estimated parameters, the steel temperature rise of similar assemblies can be calculated changing the steel cross sectional area and insulation thickness. An example is shown for a steel column (H-section, 300 × 300 × 13 × 15) insulated with calcium silicate board. The extrapolated results are compared with fire test data. It is shown that the extrapolated results give conservative results for most of the cases. Thus the method is useful for engineering calculations. However, the extrapolation overestimates the time to critical temperature if the method is applied to thinner columns under more severe mechanical conditions thus identifying the limitations of this method.

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For the purpose of determining design criteria of offshore structures, a hindcast model is presented by making use of the relationships between atmospheric pressure and gradient wind velocity, between gradient wind velocity and sea surface wind velocity, and between sea surface wind velocity and wave height of wind induced waves in the sea off Japan. The atmospheric pressure under normal condition is evaluated by an available meteorological database, whereas the atmospheric pressure under typhoon condition is estimated by using a typhoon model. The monthly and daily variations in mean wind velocity and significant wave height at specific sites are evaluated to discuss the effectiveness and limitation of the hindcast model. It is shown that simulation results are in good agreement with offshore buoy data under normal and typhoon conditions.

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