Recently, design concrete strength of 150MPa has been used, and polycarboxylate-based superplasticizer has become an essential ingredient to produce ultra-high-strength concrete. In this study, the main chain length of polycarboxylate-based superplasticizer was focused on to optimize performance of dispersing ability at low water cement ratio on ultra-high-strength concrete. Short main chain length exhibited high dispersing ability and low concrete viscosity at low water cement ratio. It was estimated that the thickness of water film on cement particle demanded three times of the main chain length. The main chain length was found to have influence on dispersing ability.

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The purpose of this paper is to propose a criterion for the occurrence of drying shrinkage cracking of concrete. Based on the test results obtained by using the new testing apparatus in which the restraint ratio can be kept constant and the stress occurring in concrete can be directly measured, the shrinkage cracking criterion based on both stress and strain was constituted. The stress and strain at the maximum load under the stress-strain relationship were discussed as well as the static strength test, and the stress reducing factor(α: maximum restraint stress ratio) and the strain increasing factor(β: maximum restraint strain ratio) were introduced. These factors were assumed to be dependent on water-cement ratio(W/C), the age at the start of drying(T), and restraint ratio(K). Moreover, since it was considered that the effects of the internal stress due to the distribution of drying shrinkage strain was remarkable, the initial slope between the water loss and drying shrinkage strain(WS_i) was discussed. Finally, both factors were expressed as a function of WS_i and K. It was found that the proposed criterion was almost described the jeopardy of the occurrence of drying shrinkage cracking, although it was very difficult to predict the occurrence of cracking exactly.

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The influence of various factors such as chemical admixture and mixing conditions on the air void system of concrete was investigated by the buoyancy method. When AE agent was used independently, the difference of quantity and quality of entrained air due to the type of AE agent was not recognized among 10 types of AE agent used in this study. However, when AE agent was used with superplasticizer, we could see big difference in air entraining due to the type of AE agent. Furthermore, the influence of mixing efficiency and grading of sand was also large besides AE agent. It was possible to control frost resistance by the appropriate quantity and quality of entrained air even if concrete was subjected to wetting/drying cycles. The section air quantity of diameter from 100 to 500 micrometer is especially effective to prevent frost damage of concrete.

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Temperature dependency of autogenous shrinkage of ultra high-strength concrete whose binder is premixed silica fume cement with W/B=0.15 is investigated. Experimental factors are temperature of fresh concrete and elevated temperature history that are emulating difference of temperature history due to placing season. As a result, the following conclusions are obtained 1) Autogenous shrinkage of ultra high-strength concrete has two stages from the point of view of a rate of shrinkage, i.e., earlier age (Stage1) and later age (Stage2), 2) Lower temperature of fresh state increases autogenous shrinkage at Stage1, 3) Higher temperature develops larger autogenous shrinkage, especially over 40°C at Stage2, 4) the reduction of autogenous shrinkage was observed in the case that the applied temperature dilation was given to the specimen before the age of starting development of autogenous shrinkage.

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The response of a mechanically anchored waterproofing membrane system located atop a building on the island of Miyako when subjected to strong winds from a typhoon in 2007 was measured, and the relationship between the wind pressure and the behavior of waterproofing membrane system was investigated. A waterproofing membrane was constructed atop the roof of a building, and the PVC membrane was fastened by fasteners at a pitch of 600 mm. The response of the wind pressure, the billowing height, and the strain of the waterproofing membrane were measured at the site of typhoon No.12. The maximum wind speed was recorded as 16.8 m/s, and the maximum instantaneous wind speed was recorded as 28.1 m/s. The waterproofing membrane was billowing and flattering at high wind velocity. As the wind pressure increased, the billowing height and the strain of the membrane increased. The values of these parameters were higher at the edges of the test specimen. The results measured on site had good correlation between the wind pressure and the response of the membrane system at higher wind velocity.

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A test method using actual plants for evaluating root resistance of sheets and their joints in membranes for roof gardens is proposed. The key point in developing a test procedure is how to make a root or rhizome surely contact to surface of a specimen or joint in it. The device with a guide cone, which enables a root or a rhizome to contact a specimen, was developed. The root resistance tests were carried out on sheets and joints of some membranes by the proposed method. The results were compared with the ones obtained by the usual method that has been widely adopted, and the advantages of the proposed test method were discussed.

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This study aimed at developing polyethylene fiber-reinforced concrete (PEFRC) with high flexural toughness and sufficient slump for precast concrete. Experimental investigations were conducted regarding influences of mix proportion of matrix, fiber volume fraction, and shape of short fiber on slump and various mechanical characteristics of the PEFRC. As a result, PEFRC with more than 40 kN·mm in flexural toughness and 10 cm in slump could be derived, due to applying high-fluidity matrix and loosely bundled short fiber to the PEFRC. Moreover, it was shown that the PEFRC possessed generally good mechanical characteristics and durability as compared with steel fiber-reinforced concrete and plain concrete, respectively.

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The widespread use of seismic isolation has necessitated a better understanding of the more complex aspects of isolation device behavior. The properties of seismic isolation devices depend upon the interaction between horizontal and vertical forces acting on the isolator. The actual hysteretic behavior of an isolation bearing under a structure subjected to severe earthquake shaking is influenced by the variation of vertical load on the isolator due to overturning forces. To identify the mechanical characteristics of lead-rubber isolators, cyclic shear tests of isolators under varying vertical load were conducted. The authors propose an analytical model for predicting the behavior of isolators under varying vertical load conditions. The model can reflect the influence of varying vertical load on isolator properties, and this capability is confirmed by simulation analyses and comparison with the cyclic shear test results. The analytical model is also used to investigate the behavior of lead-rubber isolators under loadings more severe than typical design conditions.

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Due to the various capacity limitations of shaking tables, e.g., the maximum displacement and velocity, and the amount of oil supply, it is difficult to directly reproduce large floor responses of high-rise buildings subjected to long-period, long duration ground motions. In this study, a new shaking table experiment method is developed to overcome these difficulties. A rubber-and-mass system is proposed to amplify the motion of the shaking table. To achieve an accurate reproduction of the large floor response, control algorithms are adopted to generate a special input wave for the shaking table. Full-scale substructure shaking table tests were conducted in E-Defense to verify the effectiveness of the developed method. The test results demonstrate that the substructure shaking table test can reproduce the large floor response reasonably using the input wave generated by the control algorithms.

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This paper proposes a finite element method for nonlinear sloshing analysis of the perfect fluid in free-form containers. In this paper, the discrete governing equations of free surface flows are derived based on the variational principle. The energy functional is denoted by the volume integration of the Bernoulli's pressure equation, and by descritizing this functional previously, i.e. by applying the Ritz method, the governing equations are easily obtained. The numerical examples are presented for liquid-sloshing in a circular container. Furthermore, the sloshing vibration tests for the water tanks with variously inclined side walls are conducted, and the test results are compared with the analytical results obtained by the proposed method. Through these results, the effectiveness of the proposed method in confirmed.

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We present formulations for dealing with the singularities encountered at an apex of a yield surface of generalized plastic hinges located at both ends of a 3D beam-column element. At an apex of a yield surface in a 3D stress space, the number of active yield conditions may be more than that of the dimension of the stress space. In such a case, direct application of Koiter's generalized plastic flow law leads to indeterminacy of the tangent stiffness matrix. To overcome the difficulty, we propose a simple and systematic formulation for deriving the tangent stiffness matrix, wherein application of Koiter's rule is effectively bypassed if necessary. This formulation is exact in the sense that it does not introduce any additional approximations like smoothing or cut off of a yield surface around an apex. The validity of the present formulation is demonstrated in a moment resisting frame example, where the results obtained by the present approach are compared with those by the 2D analysis.

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A single-point local search method is presented as a simplification of the multiobjective tabu search. Some improvements are made to reach the Pareto front within small number of function evaluations. The performance of the proposed method is first verified by a small mathematical problem. It is shown that accurate Pareto solutions with good diversity are obtained by using the proposed method. Pareto optimal solutions are next found for a four-span five-story steel building frame. The objective functions are the total structural volume and the compliance under the specified set of loads. It is shown that about 30 Pareto solutions with good accuracy can be found by carrying out structural analysis 200 times. The proposed method has very few problem-dependent parameters. Therefore, the method can be applied to multiobjective optimization of large structures, for which the population-based method is difficult to be applied.

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We carry out earthquake response analyses of two Nagaya models with uni-axial eccentricity considering their floor stiffness subjected to bi-directional input earthquake motions, and examine the orthogonal wall effects. The orthogonal wall effect means how walls perpendicular to the eccentric direction will control the tortional vibration. The different two Nagaya models are one- and four-unit types. We choose the floor stiffness, the shape ratio of depth to width on the plan, the eccentric ratio, the wall quantity and its ratio, and the kind of input motions and their level in the analyses as parameters. The results obtained show that the factors of the orthogonal wall effects are mainly the floor stiffness and the shape ratio. The required wall ratio of depth to width is 2.0 for motions with V_max=10cm/s, and the required yield shear coefficient of depth is 0.5 for motions with V_max =50cm/s. The kind of motions and their level do not become the factors of the effect.

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The response reduction of reinforced concrete (RC) building structures due to soil-structural interaction has been discussed generally using simplified models idealized with an equivalent elastic sway spring, because the nonlinear characteristics and frequency dependent response of surrounding soils are not well quantified in large inelastic range. Aside from these nonlinear soil deformations, the response of RC structures on spread foundation could decrease with nonlinear base slip behavior, if the foundation base shear exceeds the friction strength at the base of the footings. The behavior has been verified through a full-scale shake table test of RC buildings with spread foundation on the concrete slab. In this paper, the upper-bound response of RC structures with a simple nonlinear sway spring is estimated generally based on dynamics theory. The potential energy of the structure is conserved during base slip, so that the maximum response of the structure during base slip is to be limited from the velocity and restoring force when the base starts to slip. The maximum velocity can be evaluated on the assumption that the maximum input acceleration acts on the structure during the preceding period of base non-slipping behavior. Therefore, the maximum restoring force can be estimated using the maximum input acceleration, the base friction coefficient, and the mass ratio of the upper structure and the foundation. The accuracy of the theoretical estimation was verified through the nonlinear responses of the models with wide range of parameters.

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A dual system of RC structure consisted of moment-resistant open frame and new type of shear wall is proposed by authors. The features of the structural system are to remain the same story drift of each story and to posses the large energy dissipating capacity. The former is owing to the rigid shear wall panels and avoids the crashing of a particular story of the structure. The latter is according to the steel coupling girders which are spanned narrowly between the two rigid shear wall panels and are acting as hysteretic dampers due to their compulsorily large deformations. Tests are carried out on two specimens of one-fourth scaling model. These are the wall parts of one-bay and three-story of the proposed structural system. The results of cyclic lateral loaded tests show large energy absorbing capacities without strength deteriorating manners until the fracture of coupling girders occurs.

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The RC framed shear walls are popular to resist the earthquake loads efficiently. The recent past earthquakes reveal that they are vulnerable to large seismic excitation. To satisfy the demand of high energy absorption in large earthquake, it is necessary to retrofit the existing framed shear walls with converting the failure mode from shear to flexural or uplift one. Considering this fact, the retrofit technique of utilizing additional concrete sandwiched by steel plates and PC bar prestressing is proposed here. The proposed retrofit technique is experimentally investigated and analytically evaluated. The seismic performance of the specimen is also discussed here.

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This study concerns the bond splitting strength of recycled concrete beams with recycled coarse aggregate of a quality lower than that of high quality recycled coarse aggregate. Medium quality recycled coarse aggregate shows high water absorption because of the mortar remaining in the aggregate material. Thus, drying shrinkage cracks tend to occur easily in the recycled concrete. In order to suppress this drying shrinkage, this study used recycled concrete with a mixture of medium quality recycled coarse aggregate and normal coarse aggregate. The result of the study indicated that, when compared with the conventional recycled concrete in which normal coarse aggregate is completely substituted by medium quality recycled coarse aggregate, the recycled concrete with a mixture of medium quality recycled coarse aggregate and normal coarse aggregate has a higher bond splitting strength of lap splices. Further, when a drying shrinkage reducing agent was added to the recycled concrete consisting of the medium quality recycled coarse aggregate and normal coarse aggregate, the drying shrinkage was reduced and the occurrence of drying shrinkage cracks was suppressed.

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The influence of ultimate tensile strain (_εPSH) fluctuation during the Pseudo Strain Hardening (PSH) behavior on the shear strength and deformation capacity after the flexural yielding of damper with High Performance Fiber Reinforced Cementitious Composite was examined by FEM parametrical analysis. Subsequently, the evaluation methods for shear strength and deformation capacity after flexural yielding, which can give proper consideration to fluctuation of _εPSH, were proposed, and their applicability was verified. As a result of comparing the applicability of these evaluation methods with parametric analysis, it was shown that the improvement of the deformation capacity after the shear strength along with the increase of _εPSH and flexural yielding could be well evaluated. Furthermore, as a result based on comparison between the test results in the past research and the evaluated value, this proposal equation evaluated all the test results in the past research to be safe.

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A seismic response control design procedure of reinforced concrete multi-story asymmetric building using visco-elastic dampers is proposed in this paper. In this procedure, the size of dampers are determined based on equivalent linearization technique and using two idealized model, equivalent single-story model and equivalent SDOF model. The applicability of the proposed procedure is examined through nonlinear time-history analyses of four-story asymmetric frame building models. The results show that the peak story drift of building models with dampers are within the target story drift.

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The objectives of this research are to clarify the shear behavior of reinforced concrete thin beams with main reinforcement arranged singly and stirrup of no closed-type and to derive the formula to evaluate the ultimate shear strengths. A total of 10 specimens were constructed and tested under simulated seismic loading. The primary test variables were amount of shear reinforcement, compressive strength of the concrete and the shape of stirrup. As the test results, the structural performance is degraded in comparison with R/C beams with main reinforcement arranged doubly and stirrup of closed-type. The reason is as follows.
1. Damage of concrete is concentrated on the core area of cross section.
2. The shear reinforcement effect of stirrup , which is no closed-type, decrease in comparison with stirrup of closed-type. Because of being determined by anchorage ability of 180° hook.
Then being based on above results, the formula to evaluate the ultimate shear strengths of R/C thin beams with main reinforcement arranged singly is developed. Fairly good agreement between experimental and calculated results of the ultimate shear strength is shown.

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Structural retrofit work meets many difficulties for the continuous occupation of buildings, and also sometimes spoils building external appearance. An integrated façade system is researched and developed for solving those problems. Here, seismic performance is improved using seismic energy dissipation devices, and also external and environmental designs are upgraded. In this paper, the integrated façade system, which has the buckling restrained braces arranged continuously diagonally as lovers, is studied. A design method applied to structural retrofit is proposed based on loading tests and structural analyses.

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An experimental study was carried out on slip-type and non-slip-type exposed column bases subjected to cyclic bi-axial bending moment to investigate restoring force characteristics. Based on test results the following conclusions were drawn:
1) Non-slip-type column bases showed non-slip-type multi-linear cyclic curves, linear from the origin at each loading cycle.
2) Slip-type column bases showed complicated slip-type cyclic curves, especially in 45-degree cyclic loading because of plastic elongation of the central-row of anchor-bolts.
3) Energy absorption performance of non-slip-type column bases on cyclic loading tests was better than that of slip-type ones.

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Buckling Restrained Braces (BRBs) are commonly used as ductile bracing elements in seismic lateral resistance systems. A key limit state governing BRB behavior is overall flexural buckling. However, when the wall thickness of the restrainer is relatively small compared to the core plates section, the restraint conditions against local buckling of the core plate about its strong axis can be critical for the stability and strength of the BRB. In this study, cyclically-loaded experiments and numerical analyses were carried out using various tube restrainer configurations, and the local buckling restraint conditions are discussed and proposed using these results.

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This paper presents a multipurpose set-up system called “test bed” for large shaking table tests. The test bed is composed of multistory box-trusses with concrete mass of inertia supported by linear slider bearings in each layer. It supports self-weight, and gives horizontal inertial force to the specimen frame when they are connected together and placed on the shaking table. In this paper, shaking table tests with a single-story sample frame with beam-end damper are carried out. Their results are compared with the analytical results and the performances of this set-up is discussed.

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As the performance-based design is coming to be widely used for earthquake-resistant buildings, it would be more necessary to evaluate the building performances through earthquake dynamic responses. Hysteretic dampers are popularly installed in high-rise buildings in ordert to control the earthquake responses. In this paper, we propose a simple method to optimize hysteretic-damper strengths so as that the story-drift responses are distributed with the targeted value equally for all storys of a building under earthquake excitations. The applicability of the method was demonstrated by a numerical calculation of various frame models through a nonlinear frame analysis.

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This study is on the bond characteristic between a flat bar and a concrete in the expansive concrete filled steel tube with the flat bar in center. This tube is used for the brace member of the energy dissipative braced frame. To obtain the bond characteristic, I carried out the repeated tension and compression loading test of it. And then I obtained the relationship between the bond stress and the slip on the interface of them under tension load. Based on this relationship, by solving the differential equation on this bond characterisic, I found the possibilty of the evaluation of this tube's stiffness.

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In this paper, a SRC flat beam system, which was rigid frame construction that consisted with SRC flat beams and normal SRC columns, was researched. The flat beam of this system has wider width than columns have and shorter depth than nomal beams have. Steel is placed eccentrically in a beam section if the flat beam and the column were jointed eccentrically. In this case, it is necessary to consider unsymmetrical bending when flexural strength of the SRC flat beam section is estimated. In this study, cyclic loading test of a SRC cruciform joint specimen was carried out to investigate performance of the SRC flat beam system. As a result, the specimen showed restoring force characteristics of flexural type, and an estimating method of flexural strength of SRC section that had eccentricity of steel was shown in this paper.

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The paper is intended to summarize findings from fire resistance tests on simply supported beams conducted as part of a study on the fire resistance of steel-concrete composite beams. The specimens were comprised of H-shaped steel beam and overlying composite slab with profiled steel decks, with studs at the interface. The composite beams were designed to be partial composite. A total of six models were tested. The test parameters included the level of load, cross section of steel beam and presence of fire protection. Based on the test results, a new formulation is proposed to calculate with a good accuracy the flexural strength of composite beam on the basis of the plastic theory taking account of the heat-induced degradation of steel / concrete materials and shear capacity of studs.

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