In this paper, we propose a method for estimating the carbonation rate of concrete that will be used in actual buildings and subjected to natural environments. This method is established on the basis of results of an accelerated carbonation test and by taking the following three steps:
 (1) Collection and analysis of past accelerated carbonation test data.
 (2) Understanding of the actual progress of concrete carbonation in existing buildings subjected to natural environments.
 (3) Proposal of a carbonation rate coefficient ratio (R) that correlates results of an accelerated carbonation test to results of a carbonation test in existing buildings.

抄録全体を表示

 We simultaneously studied increase in carbonation inhibition effect by densification of the concrete structure due to pozzolanic reaction and decrease in the same due to consumption of Ca(OH)₂, and we attempted to shed light on the effect of mixing fly ash on the durability of concrete with the help of accelerated carbonation test. As a result, In the concrete having the same water-cement ratio, we studied carbonation inhibition effect by combining the effect of consumption of Ca(OH)₂ due to pozzolanic reaction of fly ash and increase in compressive strength. Based on the compressive strength of concrete and Ca(OH)₂ amount, we could demonstrate the carbonation inhibition effect of fly ash mixed concrete.

抄録全体を表示

 In this study, for the purpose of improvement of estimation accuracy for compressive strength of concrete by ultrasonic method, a measurement method for ultrasonic velocity and a strength estimation method for concrete were investigated. In the experiment with reinforced concrete members of actual size, the precision of proposed method for measuring ultrasonic velocity of inner concrete was confirmed to be high. Further, the estimated value of compressive strength of concrete in structure by proposed strength estimation method was close to the actual measurement value.

抄録全体を表示

 This study aims to develop an environmental impact assessment methodology for concrete. Firstly, we discussed the environmental burden factors of concrete, which should be considered and are able to be assessed, and their inventory methods, and proposed an integrated assessment method of environmental impacts for concrete. Then, 15 kinds of embodied energy and emission intensity data, and 9 types of environmental impact intensities I₁~I₉) that consider different environmental burden factors were calculated for 36 kinds of raw materials of concrete, concrete mixing, and 5 types of transportation, by using Bottom-Up Method, and on basis of the modified version (LIME2) of LIME (Life-Cycle Impact Assessment Method Based on Endpoint Modeling), respectively. Finally, the environmental impact indexes (EII) of 6 series of fly concrete were calculated by using 4 kinds of the environmental impact intensities (I₁, I₆, I₈, I₉). The calculating results show that (1) recycling does not always decrease the environmental impact of concrete, unless recycling method is suitable; (2) the EII using the I₆ that integrates the environmental impacts of 15 kinds of burden factors, would rationally evaluate the environmental impact of concrete. However, the EII using the I₆ that was obtained by subtracting the environmental burdens of recycled wastes' disposal can clearly reflect the environmental benefits of recycling.

抄録全体を表示

 In this study, for the diffusion of the material recycling method for a polyvinyl chloride (PVC) wastes, the authors developed the recycled sheet by mixing multiple kinds of the PVC construction wastes. As a result, there is not specific influence for the mechanical properties of the sheet by mixing multiple kinds of the PVC construction wastes. It became available to estimate the mechanical-properties of the sheet on the basis of the experimented results. Furthermore the durability of sheet was evaluated that it is dependent of the plasticizers used for the recycled PVC compounds.
 These observations indicated that the recycling method is able to recycle multiple kinds of the PVC wastes together, it is instructive to be for reducing the amount of the construction wastes and a sustainable society.

抄録全体を表示

 Field experiment on hydrodynamic forces exerted on a free-standing box-shaped structure partially submerged in inundation flow was conducted by using a metal frame setup on a natural riverbed wherein Froude number F_r ranged from 0.45 to 1.80. In result, following features were observed. Drag coefficient C_D is significantly affected by both the Froude number and the blockage ratio in subcritical flows in the manner that higher C_D is induced by smaller F_r as well as larger blockage, resulting in C_D varying from 0.6 to 2.1. However, their effects are negligible in supercritical flows, resulting in nearly constant C_D of 1.2±0.2, which may be attributed to reattachment of the separated flows on the side walls of the structure. Uplift coefficient C_upl is predominantly governed by F_r in a way of power law. With the elevation of F_r, the action point of uplift force shifts gradually to the upstream edge of the base of the structure, which develops a larger overturning moment.

抄録全体を表示

 Aging effects of oxygen and water / saltwater on mechanical properties of two types of covering rubbers for isolation rubber bearings were experimentally studied. Rubber A (natural rubber) and Rubber B (synthetic rubber) were selected for the testing. Accelerated aging test corresponding to 80 years, water / saltwater cyclic spray test for 60 days, and the combination of the two tests were conducted for the both materials. Considering the configuration and the environmental condition of rubber bearings, rubber blocks, not dumbbell specimens, were chosen and exposed to the above deterioration factors. From the mechanical properties of dumbbell specimens cut out from the deteriorated rubber blocks, it became clear that oxidation affected the both specimens much larger than water / saltwater and that covering rubber was effective for protecting rubber bearings from those deterioration factors.

抄録全体を表示

 Base isolation has become increasingly used not only for short buildings but also tall buildings, especially in Japan. It is recognized as an effective strategy for reducing displacement and acceleration in the superstructure. In design, rigid superstructure is generally assumed. However, for tall buildings, flexibility of the superstructure also plays an important role in the response of the structure. As a result, expensive rigorous dynamic analysis is required. This study, therefore, aims to propose a simplified approach which takes into account flexural superstructure to approximate the maximum response of base isolated structure using response spectra. Verification of the proposed theory indicates good accuracy. Hence, the theory can be used to design the isolation system to achieve a desired performance level.

抄録全体を表示

 As previously reported, we have proposed a vertical distribution of seismic design load for seismically isolated buildings (SIBs) corresponding to diversity of seismic isolation devices such as hysteretic dampers and fluid dampers. This proposed seismic design load is obtained from the relationship between response amplification caused by higher-mode responses and Isolation ratio which represents structural characteristics of SIBs.
 In this paper, we build a concept of Equivalent Isolation ratio I_eq which has applicability to various dampers in order to simplify an evaluation formula of vertical distribution of seismic design load. Moreover, an effect of the combination application of various dampers on vertical distribution of shear force coefficient of SIBs is analyzed on the basis of Equivalent Isolation ratio I_eq.

抄録全体を表示

 In order to reduce the accelerations of top floors for mid-rise base isolations subjected to strong earthquakes, a tuned mass damper (TMD) system is proposed. The performance evaluation results of the existing structures and the previous researches show that large accelerations occur on the roof for the mid-rise base isolations. With a TMD installed on the roof, simulations are carried out for a 10- and 15-story base isolation to investigate the effectiveness of the TMD. The following conclusions are drawn: (1) the TMD is effective in reducing the roof acceleration; (2) optimal parameters exist for the TMD; and (3) a second mode TMD is more effective than a first mode TMD. Finally, a second mode TMD utilizing the top floor is designed, and the practical weight and stiffness of the top floor are discussed followed by the simulation results.

抄録全体を表示

 When existing piles are reused, they are inspected using the pile integrity test (PIT) to judge whether they are appropriate for reuse. The evaluation of pile soundness heavily depends on the experience of PIT examiners. This paper describes the objective and quantitative evaluation method for pile soundness using PIT. The major findings of the study are summarized as follows. 1) The size of pile crack depends on the amplitude characteristics of PIT waves. 2) The size of pile crack can be evaluated using proposed “crack factors” that are calculated from the quantified values of the amplitude characteristics.

抄録全体を表示

 It is important to evaluate the strength and the behavior of shear-lag to clarify seismic margin of reactor equipments. However, there are a very limited number of experimental studies that focus on the mechanical characteristics of shear-lag. This study carried out the cyclic static load test and the simulation analysis, and evaluated the mechanical characteristics and the maximum strength of shear-lag. A half-scale specimen of a shear-lag and surrounding shear walls was used in the experiment. Elasto-plastic analysis was made using the three-dimensional finite element model.

抄録全体を表示

 In Japan, construction of wood structures for public buildings is encouraged for environmental reason. For example, low-rise large wood buildings sometimes involve RC cores to enhance the seismic performance and the fire resistance. However, it is difficult to evaluate seismic force distribution and stress between wood parts and core parts of such horizontal hybrid structures. In this paper, applicability of simplified modeling method by two-dimensional continuous body to simulate the unique basic vibration properties of horizontal hybrid structures is discussed. Based on the theoretical approach, practical formulae of amplitude and distribution of seismic force acting on wood parts are proposed. The accuracy is demonstrated by comparison with earthquake response analyses, and they give close agreement with them.

抄録全体を表示

 This paper investigates the flexural performance of a typical shear wall with no boundary column through experimental, numerical and theoretical approaches, as follows:
 1. The specimen failed in a brittle manner with concrete crushing at the bottom with a height of 2.5 times as the thickness.
 2. Hinge length on the tensile side of the specimen was higher than that on the compressive side, which was considered in a bending analysis proposed in the paper.
 3. The proposed analytical method evaluated the flexural performance of the specimen well.
 4. Simple equations were derived to evaluate the flexural deformation capacity of this type of wall.

抄録全体を表示

 The paper shows the static loading test results on full-scale reinforced concrete building utilizing columns with wing walls. The specimen is a five-story reinforced concrete building with 1×2 bays and height of about 19m. The wall frame has large openings in longitudinal direction. The gaps was formed along the edge of wing walls to make a frame consisting of columns with wing wall and beams. Attached wing walls works as a rigid zones of soften beams and additional column section, and the specimen shows calculated strength of beam side sway mechanism. The moment curvature distribution of the 1^st story wing wall frames are evaluated experimentally in the test. The inflection point derived from the interpolation between moment resisting frame and wall frames approximates the test results. The residual crack width of the beam elements becomes large for the damage concentration on the local hinge region. The damage levels evaluated from the hysteresis is smaller than that evaluated from residual crack width in the test.

抄録全体を表示

 Accelerated corrosion tests were performed on ten specimens which are designed as elements cut from RC columns in order to investigate cracking behaviors and increasing strains of bars due to chloride attack. The variable factors are concrete strength, longitudinal and transverse bar arrangement, and covering depth. Test results indicated that a corrosion cracking is most early appeared on the surface above transverse bars of the specimens having lower concrete strength and thinner cover, and that corrosion cracking behaviors greatly depend on concrete strength, namely, pore structures in the cement paste. An ultrasonic inspection can early detect damage around corroding bars.

抄録全体を表示

 Steel slit shear walls enhance seismic performance of buildings significantly but when they are designed to span a column to column, some difficulties arise in construction due to their size. Flexibility in design and construction can be dramatically improved by composing a slit shear wall with a set of narrow units with large aspect ratio assembled on-site, while keeping the wall's structural performance. An experimental study was conducted to examine the behavior of assembled slit shear walls using low-yield-point steel. The test results showed that narrow slit shear walls placed independently exhibits slight pinching in hysteresis while those stitched each other using steel bands dissipated energy similarly to the original single wall. In addition, to guarantee a good energy dissipation for each narrow slit shear wall, the upper limit for the width-thickness ratios of links was determined based on a supplemental study of finite-element analyses. This upper limit implicitly controls the number of rows required in slit shear walls.

抄録全体を表示

 When SN490 beam is connected to BCR295 column, especially when the joint efficiency at beam web is low, there is a high possibility that the connection does not meet the joint coefficient criteria of connection strength. A comprehensive evaluation of the plastic deformation capacity of these connections is necessary. Nineteen beam-to-column specimens with joint coefficients ranged from 0.97 to 1.39 were tested under incremental cyclic loadings. The plastic deformation capacity, maximum strength, yield strength and full plastic strength of the specimens with different failure modes were evaluated quantitatively. The test results show that for the specimens with low joint coefficients, although the plastic deformation capacities are not particularly good, these specimens reached the minimum requirements of seismic design. The test results also indicate that the "Recommendation for Design of Connections in Steel Structures" provides accurate evaluation of both the maximum strength of beam-to-column connections and joint efficiency on the safe side.

抄録全体を表示

 The damage of steel moment resisting frames (MRFs) with exposed-type column bases which have weak anchor bolts concentrates to the upper end of columns and/or to the beam ends of the first story under seismic excitations. This happens because the exposed-type column base with weak anchor bolts shows slip-type restoring force characteristics which decreases the energy dissipation in comparison to when the bottom end of columns of the first story is yielding. In current Japanese seismic design of the weak column base type for steel MRFs, D_s value of the firsts story has to be increased to 0.05 to reduce the damage concentration at the first story. However, it remains to be clarified whether the increase of D_s value of the first story to 0.05 is suitable or not in various cases. In this paper, a series of earthquake response analyses of plane frames weres carried out to evaluate the effect of different D_s values of the first story.

抄録全体を表示

 A story of a building may collapse due to excessive column inclination caused by thermal elongation of connecting steel beams during fire. However, thermal elongation of steel beams is not investigated fully. It can be thought that the thermal elongation is restrained by the rigidity of adjacent members. Their restrain effects are modeled by a spring at the end of the heated beam. From the consideration of full scale fire furnace tests of steel beams which were constrained by the RC slab, it can be assumed that the constraining effect of the RC slab is presented by its bending stiffness. Furthermore, the stiffness reduction can be indicated by an exponential equation. This study indicates that the thermal elongation of steel beams can be predicted accurately by the simple theoretical formula for the performance based fire engineering design.

抄録全体を表示

 For the determination of wind resistance of cladding materials, tests with specimens whose size is relatively small and represents a part of the cladding system, using simplified test setups (i.e., a partial component test) tend to be performed due to their simplicity and the technical testing capability of cladding manufacturers. However, the differences between failure load (pressure) of claddings obtained by such simplified methods and that obtained under more realistic loading with specimens fully representing actual cladding systems (i.e., a complete component test) are not generally quantified. The present study examines this difference in failure loads by performing complete component tests and partial component tests using a wall system employing composite siding with metal, and discusses the parameters which influence failure loads.

抄録全体を表示

 In this paper, the influences of the curing conditions and water cement ratios on the mechanical properties at high temperatures were considered from the results of the compressive tests. The water cement ratios of specimens were 65% ～ 40%. The specimens were cured with 3 methods: air-dried, oven-dried and sealed. The results obtained in this study are as follows:
 (1) The influence of curing conditions on the compressive strength is clear at 100°C.
 (2) The strength of sealed specimens dropped sharply between 400°C and 500°C
 (3) The influence of water cement ratio is clear between 400°C and 600°C.

抄録全体を表示

 The main purpose of this study is to quantify both collapse temperatures and probability of occurrence on collapse modes for a steel subassemblage, which consists of upper and lower columns and a beam subjected to fire, in case of considering the variations in steel strength at elevated temperature. Numerical analyses using Monte Carlo (referred to as MC) method are conducted to estimate the collapse temperature. For estimation on buckling temperature of the heated column, an equation (10) giving buckling strength at the elevated temperature is proposed. From observation of the MC analytical results, the following has been clarified: the collapse modes of the subassemblage are easily changed in the case when there are little difference among the theoretical collapse temperatures of each collapse mode, on the other hand, in the case when the difference is approximately ≧ 100 °C, the collapse mode approximately agrees with the determinate theoretical collapse mode.

抄録全体を表示