Integrated coal Gasification Combined Cycle (IGCC) has received a lot of attention in recent years from the viewpoint of reduction of carbon-dioxide emissions. In this system, the coal after gasification is produced in the form of slag instead of coal ash. The slag has a tremendous amount of potential of effective use in a concrete field because of no hazardous components eluting and simplification of handling compared with coal ash. In the previous paper, we conducted a series of mortar and concrete experiments and studied basic property of the concrete with IGCC slag especially focusing on the influence of the amount of fine powder of slag and the mechanical characteristic of slag concrete. In this paper, we used the IGCC slag that had high density and low water absorption in the place of standard quality IGCC slag used in the previous report. Then we conducted a series of concrete experiments and studied basic property of the concrete with IGCC slag by comparing examination of various kinds of slag fine aggregate and natural sand. The results of experiments suggest that IGCC slag can be used in the same way as other slag fine aggregate.

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Steps are common features in our day-to-day living and working environment. Unfortunately, the occurrence of accidents on or around steps is thus inevitable. A failed visibility to see or recognize a step remains the most common attribute in these accidents. Surprisingly, appropriate methods for examining and quantifying step visibility have yet to be established. In this research, sensory scales on edge and height visibility as well as step visibility were created in order to examine mainly the effects of two factors on step visibility in sensory testing methods; easiness of visual perception of edge and height while viewing a step from the descending direction. Results of sensory tests revealed that edge visibility is independent from height visibility, and step visibility has stronger relationship with height visibility than edge visibility.

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Steps are common features in our day-to-day living and working environment. Unfortunately, the occurrence of accidents on or around steps is thus inevitable. A failed visibility to see or recognize a step remains the most common attribute in these accidents. Surprisingly, appropriate methods for examining and quantifying step visibility have yet to be established. In this research, sensory scales of step visibility were created in order to examine the effects of two factors on step visibility in sensory testing methods; observation distance from step and observation action while viewing a step from the descending direction. Results of sensory and statistical tests revealed that step visibility tends to decline as observation distance increases, and the quality and tendency of step visibility in different observation conditions varies based on the unique and individual visual characteristics of each step.

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In this study, wind response properties of high damping laminated rubber bearings (HDR) is investigated by experimental and analytical methods. According to the experimental result of HDR, horizontal creep deformation depends on magnitude of dynamic loading as well as that of static loading under the wind loading. This feature differs from other seismic isolation devices. Then we propose the simplified evaluation method and hysteresis model for time history response analysis under wind loading, which are established by taking account of the effect of creep deformation caused by dynamic loading. Firstly, we perform the wind loading test for high damping laminated rubber bearings and establish the simplified evaluation method and hysteresis model based on the test results. Next, we verify the validity of proposed models by comparing the analysis results with experimental results. Finally, we perform the time history response analysis using proposed hysteresis model.

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This paper describes the characteristics of internal pressure fluctuations induced by the wind in a 14-story building assumed for this research. The internal pressure fluctuations in the building are evaluated using a numerical simulation method that involves use of a leak-flow model and external pressures. The airtightness of external walls considered in the simulation is evaluated on the basis of past research data. It is shown that the mean value of the internal pressure coefficient is almost similar to those of the internal pressure coefficients for high-rise buildings surveyed in the past. The peak values of internal pressure fluctuations in non-Gaussian processes can be estimated by assuming a Gamma distribution for the mapping function. This paper describes also the characteristics of the maximum and minimum values of the peak internal pressure coefficients.

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Energy absorption capacity is an indispensable property for earthquake resistant structures. To equip the top story with abundant energy absorption capacity and to make energy inputs done by earthquakes concentrate on the top story result in an promising design option which has not been hither to fully investigated. In this paper, the mechanism through which the energy input moves to the top story is clarified and the design criteria for this type of structures are demonstrated to be expressed in terms of D_s-values. This type of structures can be also applied to strengthen the existing structures which are judged to be insufficient in energy absorption capacity. By adding the damage concentrating story at the top of existing structure, the seismic performance of the structure can be highly improved without disturbing its living function.

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This paper proposes a vertical distribution of seismic design load of seismically isolated buildings corresponding to diversity of seismic isolation devices such as hysteretic dampers and/or velocity-dependent dampers. This proposed method is obtained from the relationship between response amplification caused by higher-mode responses and key parameters such as Isolation ratio I and Non-linearity factor NL which evaluate structural characteristics of seismically isolated buildings. This response amplification is explained by non-linearity modal analysis with free-free vibration mode. In addition, it is confirmed that this proposed method adapts to various model of seismically isolated buildings.

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The purpose of the present study is to develop the new series of hybrid stress finite elements based on the beam-column theory, and to construct the structures analysis system, for wall structures and/or frame structures with wall members. Outline and construction of the present structures analysis system are summarized. Using the ordinary assumed displacement finite element, the Winkler's spring element is formulated in addition to hybrid stress Timoshenko's beam-column, 2D and connection elements that has been shown in the previous papers. Also, several numerical tests are performed, and the availability and the applicability of the present structures analysis system and/or approach are, discussed and examined.

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Under lateral loading on a pile group, each pile bears different lateral force depending on its position among the group. This effect of pile position is remarkable in comparison between outer piles and the other. So, the effect appears remarkably in lateral resistance elements at the outside of foundation used for seismic retrofit. The author have studied the pile group effect accounting the pile position. This paper presents a simple method to compute the pile group effect considering the pile arrangement through the 3D-FEM analysis and its comparison with experimental results.

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Vertical loading tests were performed on the bearing capacity of straight pile with enlarged grouted base using pressurized sand tank for studying the effects of the tip length and the strength of enlarged grouted base. The main conclusions are as follows. 1) When the tip length was zero, “bond failure” occurred in the early stage of loading regardless of the strength, and the pile head load reduced abruptly. 2) When the tip length was 0.83 times the pile diameter and the strength was 15 N/mm², “punching failure” finally occurred, but the same bearing capacity was obtained as in the case when the tip length was 1.3 times the pile diameter. 3) When the tip length was 1.3 times the pile diameter, and the strength was 15 N/mm², no “punching failure” occurred, and the pile head load continued to increase until the completion of loading.

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The present paper proposes an effective method to evaluate elasto-plastic buckling loads of two-way single-layer lattice domes, stiffened by diagonal braces, under vertical uniform and non-uniform loads. The domes are shallow and composed of grid chord members, connected rigidly at nodes, and supported by pins at four sides of rectangular plan. First, a formula for linear buckling load is derived based on equivalent shell analogy, followed by a study for a knockdown factor of elastic buckling loads considering geometrical initial imperfections of a magnitude up to L₀/1000 for a span L₀. The value of 0.65 or a lesser value for a knockdown factor is recommended for use to evaluate elastic buckling loads. Second, column strength curves are discussed and proposed for elasto-plastic buckling loads, and finally, the proposed strength curves are proven effective for evaluating the strength.

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Recently, the construction of the large astronomical telescope has been planned for better astronomical observation. In this project, it is necessary to design the structure of the telescope economically as well as easy to construct. Additionally homogeneous deformation of the supporting structure of the telescope is desirable to realize the stable supporting system of the main system of the telescope. However it is not so easy to design such structure, because the various tilt angle caused by the rotation of telescope for astronomical observation result in the large amount of the change in the external load. In this paper, the scheme of multi-objective optimal design for truss structures supporting large telescope are proposed and demonstrated in an actually constructed 3.8 m telescope. Using SPEA2 as multi-objective optimal method, where standard deviation of nodal displacements is adopted to evaluate homologous deformation, simultaneously satisfies the requirement of both weight minimization and homologous deformation.

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Impact hammer tests were conducted to demonstrate the vertical dynamic characteristics of light frame joist floor and effect of human load on it. The specimen was 3.64m-long-span and 4.55m-wide joist floor consisted of eleven 2" by 8" dimension lumbers and 15 mm-thick plywood subfloor. Furniture and/or human (in four types of posture, respectively) loads were applied to investigate the influence on natural frequencies and damping factors.
The test results indicate, i) Human-load hardly affects natural frequencies, ii) The value of damping factor increases with the body area in contact with the floor, iii) The first natural frequency of joist floor is roughly estimated according to the theory of free vibration equation of motion for bending beam.

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Continued from the previous study, a plywood nailed joint specimen with the nails rusting was tested by cyclic and dynamic load. In addition, the shear walls with the nails rusting were tested. As a result, the following was provided.
1. The nails was liable to break in cyclic load than monotonic load.
2. As the weight remaining rate of nails decrease, the dynamic effects become remarkable and the strength increase.
3. The allowable shear performance calculated by the dynamic test has a tendency to be equal to or greater than the static test.
4. When the weight remaining rate of nails is about 98%, the allowable shear performance shows higher value than without rusting.
5. It is possible to apply the estimating methods for the racking load of the shear wall to the walls with the nails rusting.

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This paper describes the effect of arrangement and area of floor well to vibration characteristics of two storied wooden houses by means of vibration table tests. This effect of arrangement and area of floor well includes the effect of mass eccentricity. Therefore, we examine the effect of these factors by using different series of full scale specimens, separately. First, we examine the effect of arrangement and area of floor by using specimens with floor well. Second, we examine the effect of mass eccentricity by using specimens with eccentric masses instead of floor well. And finally, we examine the combined effects by using specimens with floor well and eccentric masses. The main results obtained by these experiments are as follows. Natural frequencies of these specimens with floor well are approximately 3.34 Hz that are only by 1.5% large or small compared with ones of the specimen without floor well. Specimens with floor well that situated at side of weak wall are apt to vibrate with large torsion. The relative displacements between first and second floor are apt to influenced by mass eccentricity, and those of second and third floor are apt to influenced by floor well.

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This paper discusses various effects of diaphragm flexibility on dynamic properties and seismic responses of timber structure. Equations of motion of a building with multiple discretized diaphragm elements are derived by defining reduced degrees of freedom. A method to predict seismic responses is proposed, and example structures are used to demonstrate its accuracy and advantages. Modification of the method to rationalize and improve the conventional method is also discussed, by indicating good accuracy except when horizontal diaphragm is very flexible and stiffness eccentricity is large. Finally, criteria for “rigid diaphragm” is proposed, and required values of the key parameters are clearly indicated.

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Stress relaxation tests of wood in the past involved at least one of three technical pitfalls: Initial loading periods for imposing requested levels of strain are not constant, uncertain creep strains are merged into the target strain due to local stresses at supports and/or loaded portions of the specimen, and matching specimens are not identical due to heterogeneity of wood. These technical defects lead to inconsistent judgements in the linearity tests of viscoelasticity of wood among researchers. In order to remedy these pitfalls, a bearing stress relaxation test by indenting wood surface by a small punch was introduced. The test was first applied to a natural rubber block and provided a very clear judgement of linearity. Further application to a wood block was fairly successful in that a consistent group of load retention curves was obtained in accordance with the given levels of bearing deformation. The test results suggested that the stress relaxation of wood indented parallel to the grain is nonlinear even in the low levels of bearing stress.

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This paper presents a new theoretical macro model developed for estimation of joint shear strength of RC interior beam column connections. In the model, a compressive strut is considered as failing in bending mode. Hence, the stress block concept based on the beam bending theory may be used to estimate the strut strength. The depth of compressive strut is calculated from the neutral axes in the beams and columns, which are derived from the bending theory considering axial forces in the connected members and the effect of transverse reinforcement bars in the joint panel. Finite element analyses were carried out in order to observe the behavior of the compressive struts. Analysis results showed that the process of the formation and disappearance of the strut is consistent with the adoption of the bending theory in the strut model. The joint shear strengths of specimens in a database collected from past RC beam-column joint experimental studies were calculated by the developed model and compared to the published experimental values. The results show that the model provides a theoretical explanation of joint behavior as well as a much more improved estimation than the methods currently recommended in both the ACI or AIJ codes.

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In this paper, we propose a new method to evaluate seismic capacity index, I_s, for short-period RC buildings with large eccentricity. The analytical models are one-story and one-span rectangular buildings. The parameters are each frame's strength and deformation capacity. Static and dynamic analyses are conducted. The proposal includes a strength reduction factor based on secant stiffness and deformation capacity of each frame. This factor enables to evaluate seismic capacity index more accurately than the current standard for seismic evaluation.

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In one construction method involving precast prestressed concrete (PCaPC) beams with a pretensioning system, high strength deformed bars are used instead of prestressing strands. Prestress can be effectively introduced near the bottom of the beam, which can make it lighter with less prestressing steel. It becomes important to clarify how much the bond splitting strength of the surrounding concrete is, because PCaPC beams fail from bond splitting in the prestressing process under the high bond stress. A bond test was carried out to examine the bond characteristics in the anchorage region of PCaPC beams using high strength deformed bars. As a result, the anchorage length and the bond splitting strength of high strength deformed bar for prestressing were clarified.

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A series of push-out tests are conducted to propose shear connectors in steel-concrete composite construction that uses newly developed steel fiber reinforced cement composites (SFRCC). The tests are conducted with the pitch length (D_p) and gauge length (D_g) as the major test parameters. It is found that (1) the studs arranged densely with a pitch length of 3.5 times the stud diameter (d) can possess the shear strength (per stud) not smaller than 85% of the shear strength of a single stud; (2) the group effect caused by stud spacing in gauge direction remains the same when D_g/d changed from 0.46 to 0.23. Even the studs are arranged in a gauge spacing of the minimum spacing for stud installation, no significant reduction on per stud strength is observed; and (3) when studs are closely arranged in an area with the minimum stud spacing (7.5d×5d) stipulated in current design codes, the per stud strength decreases as the studs spacing especially that in the pitch direction decreases, but the total maximum shear resistance of the connection is still significantly larger than that with normal studs spacing.

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Realistic 3D-shake table tests using E-Defense were conducted for full-scale 5-story building specimens with/without dampers to evaluate seismic performance, using ground motions of scales ranging from minor to catastrophic levels. The building was tested repeatedly, inserting and replacing each of 4 damper types. This paper focuses on the second test conducted with viscoelastic (VE) dampers. It discusses damper and building specimen, testing and table control methods, validations of test results, performance of the passive control scheme, and in- and out-of-plane bending of the VE dampers.

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Experimental achievements on the fracture toughness of wood constituting glulam in the above paper are discussed about the following items: 1) The approach based on fracture mechanics for predicting the fracture strength of wood and wood joint has some serious defects. 2) The description of ductile-like fracture seems inadequate and the J-integral at the maximum load point is doubtful as the fracture toughness for crack initiation, because the tensile softening in the load-displacement curve of wood in 3PB and CT tests is caused by multiple steps of intermittent cracking.

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The authors thank Prof. Hitoshi Kuwamura for his discussion, and the answers are as follows;
1) There would be a defect similar to crack around wood-processing, so fracture mechanics is a valid method to estimate the structural members of timber engineering.
2) For improving the estimating methods of strength including cracks in wooden materials or timber members, the development of new measuring techniques of crack propagation is needed.

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