In this paper, the effect of ground granulated blast-furnace slag on the pore structure and compressive strength of hardened cement pastes are investigated. Five different fineness of ground granulated blast-furnace slag whose Blaine's specific surface areas are about 4000, 8000, 11000, 18000 and 30000 crnVg respectively, are used as a partial replacement for normal portland cement by 15, 30, 50 and 70%. As the ground granulated blast-furnace slag with high Blaine's specific surface areas has high filling role and high rate of hydration at early ages, the porosity, threshold radius and the early strength of hardened cement pastes increases with the increase of fineness of ground granulated blast-furnace slag. Furthermore, the effects of particle size of ground granulated blast-furnace slag, combined water, porosity and threshold radius on compressive strength of hardened cement pastes containing ground granulated blast-furnace slag are examined.

View full abstract

Three specific in- situ tests to assess the water permeability and air permeability of the surface layer of concrete were examined. Test methods for permeability are the rapid water permeability by author's method, the rapid air permeability, and rapid water absorption applying Figg's method. Experimental studies on these test method examined the influences such as distance between testing points, surface sealing, maximum size of coarse aggregate and moisture content, on specific parameters obtained in three different in-situ tests. Variations of specific parameters were also analyzed and the availability of these tests to assess the permeability of surface layer of concrete was mentioned.

View full abstract

In this study, first, we measured separation-resistance of epoxy resin floor coatings applied to substrate mortar samples, in case of being loaded by a running caster. And we also measured strength properties of substrate mortar samples by three kinds of strength tests, that is, a test for compressive strength, a pull- off test, and a test for bonding strength of finishes with scrape. Secondly, we discussed the relations between the three kinds of strengths of substrate mortar samples and the separation-resistance of floor coatings.

View full abstract

High-strength flowing-concretes, having variable water-cement ratio, unit amount of water, type of cement and type of admixture, were subjected to air current drying at early ages, and propagation of cracks at early ages and their evaluation method were examined. Major findings are as follows, 1) The propagation of cracks at early ages was influenced firstly by the water-cement ratio, secondly by the unit amount of water and slightly by the other mixture parameters. 2) Crack initiation at early ages was not observed or was generally slight when it was observed for specimens with water-cement ratio of 0.45 and 0.60, while that with lower water-cement ratio of 0.27 and 0.30 showed considerable cracks. 3) Evaluation of cracks at early ages can be made by three methods: the average crack area, the number of cracks per unit area and the total crack area per unit area. Correlation between the average crack area and the water-cement ratio was particularly recognized.

View full abstract

The maturity method in which the strength increase of cement concrete is expressed as a function of an integral of the curing period and temperature of the concrete has often been applied to its strength prediction. For the purpose of the application of the maturity method to the compressive strength prediction of lightweight polyester mortars using an unsaturated polyester resin as a binder, the lightweight polyester mortars with various catalyst and accelerator contents were prepared, and the datum temperatures for the maturity equations were predicted in previous paper(Part 1). In this paper(Part 2), the maturity is calculated by using the maturity equations with the predicted datum temperatures, and the compressive strength is predicted by using the calculated maturity.

View full abstract

This paper describes the feasibility of recycling of the aged asphalt collected from membranes that are over service life. We developed a hot press technique to exclude asphalt from an aged roofing membrane. Some fundamental properties of the asphalt such as penetration, softening point and slippage length were clearly lowered. As reductions of resins, aromatics and saturated hydrocarbons were observed through a component analysis, process oil and new asphalt compound were added to the aged asphalt to recover the property. The roofing membrane constructed with the recycled asphalt reached again to the similar level in performance as new one.

View full abstract

This study was carried out to investigate quantitatively the relationship between the degree of rebar corrosion and the strength of reinforced concrete (RC) beams. After producing equations for the relationship between both the tensile properties of rebars and bond properties and the corrosion percentage of rebars, finite element analysis and bending tests were conducted for RC beams damaged by rebar corrosion. As a result, it was made clear that the strength of RC beams damaged by corrosion could be practically simulated by FEM using experimentally determined material models representing the bond properties and the mechanical properties of corroded rebars.

View full abstract

The purpose of this paper is to evaluate the stain relatively by cigarette smoke of finishing materials from a viewpoint of visually. Based on the exposure test in smoking room, we had manufactured two types accelerating devices (rotate test piece type and sinking smoke type) for finishing materials to add the cigarette smoke stain. These devices were designed to instantly produce stain which are collectively to the actual stain. As results of consideration, the stain which was added by two devices had high correlation possibility with actual stain measured by COLOR DIFFERENTIAL except a few materials. Therefore we present two principal devices to evaluate the smoke stain for fini shine materials.

View full abstract

Two types of extreme distributions with the lower and upper limits for modeling the annual maxima of earthquake motions were derived from the theoretical approach similar to that by Cornell (1968). The one was a type IV extreme distribution, called in this paper, based on the attenuation relationship between the earthquake magnitude, fault distance, and peak ground acceleration with its upper limit independent of the earthquake magnitude. The other was a type V extreme distribution, formulated in this paper, based on a realistic assumption of the maximum earthquake magnitude in Gutenberg-Richter's relationship between the magnitude and frequency of earthquakes.

View full abstract

In order to evaluate annual maximum wind speeds due to typhoons, a new probabilistic procedure was proposed in which differences in the average time between observations and calculations were considered. Comparing full-scale observations and wind speeds calculated from a typhoon model, it was found that the average time of the calculated wind speeds was much more than 10 minutes, and the calculated wind speeds did not include the small scale variation which was found in the observations. By introducing the probabilistic procedure into the Monte-Carlo technique, the calculated probability distribution for 10 minutes of mean annual maximum wind speed had better agreement with observations than those by the conventional approach which underestimated annual maximum wind speeds.

View full abstract

To establish rational seismic design method on wood frame constructions, it is important that the relation between seismic input energy and maximum response displacement is made clear. In this paper, a concept of probability distribution of energy input ratio on single-mass system is introduced, and the relation above mentioned when input motions are stationary white noise is examined. Suceedingly, a definite relation between seismic motions and stationary white noise is supposed, and the prediction method on seismic maximum response displasement is considered. As a result, it is recognized that predicted values are nearly agree with the upper bound of analyzed values.

View full abstract

Using more than two hundred JMA-87 type strong-motion records we show that pseudo-velocity response spectra are noticeably different from Fourier acceleration spectra in several occasions because response spectra are sensitive to other frequency components or attenuation due to dispersion but insensitive to duration. Therefore, regression coefficients such as magnitude coefficients, attenuation coefficient, and site amplification factors for response spectra and Fourier spectra show clear differences. We conclude that physical characteristics of strong motion cannot always be represented by the regression coefficients for response spectra.

View full abstract

This paper presents an analytical approach to the optimality of ploy-linear type hysteretic damper useful for near-field ground motions such as the Hyogo-ken Nanbu(1995) earthquake on the basis of seismic random earthquake response analysis. Numerical calculations are carried out for six-degree-of-freedom structural systems with the damper. From two viewpoints of preservation of structural seismic safety and improvement of structural amenity, the optimum parameters of the damper are determined in such a way that the structural systems suffer no damage under medium or strong earthquake excitations, while the systems suffer only minor recoverable damage under severe or catastrophic earthquake excitations. The applicability of the optimum poly-linear type hysteretic damper based on the stationary non-white random process is demonstrated through the simulation analysis using the recorded earthquake accelerogram during the Hyogo-ken Nanbu earthquake.

View full abstract

In this paper, elastic-plastic dynamic response analysis of one story vibrational models with eccentricity are carried out From results of analyses, it was concluded that in eccentric structures having the optimum strength distribution which can be obtained by means of modal analysis no damage concentration occurs in specific structual planes. In structures having general (not optimum) strength distribution, damage concentration can be estimated by applying the parameter pti which indicates the defference between the actual strength distribution of the structure and its optimum strength distribution.

View full abstract

Dynamic characteristics of a composite foundation of wall and pile group are investigated using the results of forced vibration test and earthquake observation. It is clarified that the interior piles show similar vibration mode to that of the wall foundation, and the existence of basement and interior piles restrict the natural vibration of the interior soil. The analytical results using an axisymmetric FEM show the shear force during earthquake is largely burdened by the wall foundation and that is large at the deep part of the soil. The effectiveness of the simplified lumped-mass model is verified through earthquake response analyses.

View full abstract

This paper attempts to mathematically formulate the total input energy of secondary structures under earthquake, which stand on the primary structures. First, the total energy input of the primary structures is found to be simply expressed in terms of wave components of the seismic ground acceleration, neglecting the free vibration of the system and the influence of the phase angles between wave components. The acceleration response can be also expressed in terms of wave components of the ground acceleration, neglecting the free vibration and phase angles. Based on the acceleration response, the total energy input of the secondary structures can be formulated. As a result, the energy spectrum of the primary structure and the energy spectrum of the secondary structure can be directly related one another. Mathematical results are compared with numerical examples and are proved to be applicable to practical design purposes.

View full abstract

A series of drained triaxial compression tests were performed on sand samples for the determination of the angle of the internal friction (φ_d) in order to investigate the effects of sample disturbance on the φ_d a and also to study the 0 φ_d-N_1 relation in the range of N_1>30 for sandy soils, where Ni is the normalized SPT N-value by effective overburden pressure. The following were concluded. 1) Both the relative density and φ_d of TS sample (samples obtained by rotary-type triple-tube method) were affected by the sample disturbance. However, the effects of sample disturbance on φ_d is only 1.4 to 2.6 degrees, this is much less than that for liquefaction strength. 2) In the range of N_1≦30, the N_1-φ_d relationship for TS sample is totally corresponding to that for FS sample (by in-situ freezing method), and the relationship can also be represented by the empirical correlation proposed by Hatanaka and Uchida(l996) for FS sample. 3) Though the data is limited, the correlation of φ_<d(FS)>/ φ_d<(TS)>=1.06 can be seen for the natural sandy deposits in the range of N_1≦30. 4) In the range of N_1>30, the average value of the φ_d for TS and BL samples (by block sampling) is 38°, and there is no increase in φ_d with the increase of N_1. Based on the conclusion 3), the φ_d for in-situ sandy soils in Ni>30 can be converted from 38°to 40°. 5) The empirical correlation relating N_1 and φ_d in a wider range is tentatively proposed as φ_d=(20N_1)^<0.5>+20(3.5≦N_1≦20) and φ_d =40° (N_1>20) based on the test results and discussions shown above.

View full abstract

The purpose of this paper is to estimate the elasto-plastic buckling load of rigidly jointed single-layer latticed domes under vertical load. The value of As is adopted as to the geometric parameter of the domes. An elasto-plastic buckling analysis is carried out. Then the relation between the elasto-plastic buckling behavior of the domes under uniform load and the value of As is examined. In addition, the same analysis is carried out in the case of under one-side uniform load and under concentrated load. As a result, the elasto-plastic buckling load of the domes under vertical load is estimated by the linear buckling load of the domes or member yield load.

View full abstract

The ultimate strength of double-layer grids is determined by the member buckling and yielding. After buckling, the grids lose most of their strength. In this paper, we investigate the structural properties of double-layer grids with eccentric joints to improve deformation capacity. These grids consist of units of truss connected together by eccentric joint members. The loading tests and numerical analysis are carried out to investigate the influence of the rigidity of eccentric joint members and the difference of the progressive collapse mechanisms. As the result, these grids show stable behavior compared with that of the conventional grids.

View full abstract

A static lateral loading full-scale test is done for the actual two-storied wooden houses. The purpose of the test is to investigate the load-deformation relationship, to compare the observed with designed strengths, and to know the process of progressive failure. The results of the static loading test are described also with the summary on the construction of the testing houses and the loading and observing methods of the test. The principal conclusions obtained are summarized as follows: 1) The load and the deformation have almost linear relationship until the average angle of relative shear deformation of the houses becomes 1/120 rad., the allowable limit in the usual seismic design of wooden structures for moderate eathquakes. 2) The lateral strengths of the whole structure and its frame consisted of braces, columns and beams are more than 1.5 and about 0.5 times the required design strength, respectively. 3) The lateral strength suppored by wall elements is up to 80% of the total one of the whole structure. 4) The break at the top of some columns in the first story finally results in the collapse of this story and then the inertial force of a heavy tiled roof caused by the succeeding falling of upper story produces the total collapse of the houses.

View full abstract

The main objective of this paper is to propose an evaluating equation for deformation capacities of reinforced concrete columns determined by flexural failure, which is caused by the compressive failure of the core concrete. The effects of the compressive failure of the core concrete become significant for corner columns subjected to varying high axial load. Therefore, these problems are discussed paying special attention to the effects of the varying axial load. The proposed equivalent axial load ratio was found to be effective to apply equations to columns with varying axial load.

View full abstract

To investigate the correlation between local bond splitting behaviors and average ones in reinforced concrete members, local bond stress (τ_b) versus slippage of reinforcement (s) relationship was proposed in the preceding study (Part 1). This study presents the results of analysis performed to investigate the adaptability of the proposed τ_b-s relationship to average bond behaviors. Analyzed bond splitting strengths show a good correlation with experimental values observed in previous studies. Influence of structural factors, such as bond length, Young's modulus of reinforcement, concrete strength, concrete thickness and specimens' scale are also analyzed and discussed in consideration of the experimental results.

View full abstract

In order to evaluate the limit earthquake resistance of multi-story steel frames influenced by the strength and stiffness ratios of members and the rigidity of column bases, a series inelastic response analysis were carried out. From the analysis results, the damage distribution rules of multi-story steel frames were proposed. Conclusions are summarized as follows;l)As the stiffness ratio of beam and column becomes small, damage concentrate on the lower end of columns of the first story. 2)Damage of the lower end of columns decreases with the decrease of the rigidity of the column bases.

View full abstract

Authors have already reported a method of elasto-plastic analysis of concrete filled circular steel tubular stub columns subjected to axial compressive load, which took account of the lateral interaction between steel tube and infilled concrete (so called as confinement effect). In this paper continuously, parametric studies by using this analytical method are conducted and influences of the parameters for the enhancement ratio of axial compressive strength are elucidated analytically. In addition, examinations of existing experimental data for the axial compressive strength are carried out. By combining these experimental results with the analytical results, a practical method of evaluating the confinement effects is proposed.

View full abstract

The vortex method is one of the methods for simulating high Reynolds number flow problems of incompressible viscous flow. In this paper, the equations of the vortex method are formulated from the integral equations of equation of continuity and Navie Stokes equations by using Gaussian distribution for vortex model. The equations are expressed in terms of vortices in internal domain and these on boundary. And then it is shown that the vortex method is one type of boundary element methods.

View full abstract

In this paper, buildings are composed as three-dimensional "form" by using a new systems technique of intelligent artificial life. Cubic cells which are basic spaces of three-dimensional forms are proliferated to specified directions according to surrounding conditions. At every proliferation step various architectural evaluations are performed, and degrees of adaptation to environments are obtained. The purpose of this paper is to compose a multi-optimization-system with evolutionary evaluation in which optimal forms of architectural SD-structures and optimal membership functions of evaluations for phenotypes can be obtained by using Genetic Algorithm(GA) originated by Holland and Goldberg. First, a model of GA is employed, and surrounding conditions are coded as genotype. Next, it's phenotypes are estimated, and employed genetic processing of crossover and mutation is performed, so that genotypes with more excellent degrees of adaptation emerge. Finally optimal forms with optimal membership functions for evaluations can be obtained.

View full abstract