In this paper, the effects of stress state and loading time on deformation resistance of fresh mortar are investigated quantitatively, and the relational formulas between shearing strain rate and shearing stress, mean principal stress as well as loading time are induced by applying the mechanical constitutive law which the authors have already proposed on the assumption that fresh mortar is a kind of particle assembly. Moreover, the formulas for calculating apparent viscosity are given, which is defined as the ratio between shearing stress and shearing strain rate. As the results, (1) Shearing strain rate becomes higher with the increase of shearing stress in each stress state. (2) Shearing strain rate drops off with loading time in visco-elastic state and visco-elasto-plastic state, but increases in failure state. (3) Shearing strain rate decreases with the increase of mean principal stress in each stress state. And these results are verified by a series of shearing tests using mortar which is in from dry state to high flowing state.

抄録全体を表示

Freeze-thaw expansion of concretes is mainly controlled by air content rather than type of cement or drying initiation ages. However with a 4.5% of air content, considerable expansion at 300 freeze-thaw cycles, leading to a fracture, may occur when subjected to drying at early ages depending the type of cement and water-cement ratios. Use of blended cement with a high water-cement ratio should be accompanied by sufficient moist curing at early ages. Difference in pore volume at the radius ranging from 1,800 to 10,000 A was found between damaged and undamaged concretes during freeze-thaw test. These pore regions increased considerably with drying at early ages. Freeze-thaw scaling increased when a drying initiation age became earlier. Scaling resistance can be increased by a moist curing immediately after concrete placement, but a decrease in water-cement ratio was still necessary when blended cement was used. Amount of scaling was highly correlated to a pore size distribution within 1 cm from the surface, especially to a pore volume more than 560 A in the radius. Pore volume of this region is likely to increase when subjected to dying at early ages. Degradation due to scaling can be evaluated by compressive strengths at drying initiation ages and a scaling degradation grade was proposed. Moist curing period necessary for assuring scaling resistance was given.

抄録全体を表示

This paper presents a design procedure for external wall materials. It is significant and unique because it proposes a material design procedure which enables the selection of optimum materials in response to user's request based on a life-cycle assessment. The quality of material was evaluated qualitatively in three different terms, performance, economy and environmental conservation. Quantification was carried out as follows. For performance evaluation, the qualities of materials were graded and evaluation points were calculated by AHP (Analytic Hierarchy Process). Economy was evaluated based on the life-cycle cost. Evaluation in terms of environmental conservation was made according to the life-cycle carbon dioxide. The.material most satisfactorily meeting the design requirement in terms of a combination of three factors was selected as an optimum option.The suitability of the material was verified by model-based simulation for external walls to be used at a industrial plants of large scale steel structures.As a result, the validity of the proposed material design procedure was verified.

抄録全体を表示

The purpose of this study is to present the relative evaluation method of slipperiness of floors and walls with hands from the viewpoint of safety. First, sensory tests were carried out to make sensory scales of slipperiness on various samples with hands and evaluation scales on that from the viewpoint of safety. Next, slip resistance, which is corresponding with sensory scales, was measured by the slip meter adapted from that of handrails and grab bars developed in the former research by author. Then, relation between evaluation scales and slip resistance was presented as a relative evaluation index. Finally, the relative evaluation method of slipperiness of floors and walls with hands from the view point of safety was presented.

抄録全体を表示

Sounds generated from floors by various human action (called the floor sounds) are usually recognized as noise. On the other hand, floor sound may create an atmosphere of sports. In this study, a sensory test by athletes on the effect of floor sounds of atmosphere in playing was carried out dealing with several floor samples, and evaluation sensory scales was composed. Then, the relationship of sensory scale and floor sounds generated dealing with the developed pronouncing simulator in former study was considered. From the results of this study, the evaluation method of the effect of floor sound in playing was presented.

抄録全体を表示

Based on Mindlin's plate theory, it is presented a free vibration analysis of plates with a lumped mass. By using the method of superimposition, it is shown that solutions which satisfy both the differential equation and the boundary condition are obtained. The rectangular plates under consideration are as follows : a) all edges simply supported and b) all edges built-in. Eigenvalues of four digit accuracy are provided for a wide range of plate aspect ratio. Numerical results are compared with those by Rayleigh-Ritz method and interpolative values using Dunkerley's equation, to verify the accuracy of the proposed method.

抄録全体を表示

The study investigates the validity of the proposed model for a dynamic response analysis of soil-pile system from numerical results of thin layered element method and Penzien model. Furthermore the numerical results of the proposed model was compared with earthquake observation results of pile group foundation. Numerical results of the proposed model considering frequency dependency and radiation damping of dynamic interaction spring agree with analyses by the other analytical methods and results of earthquake observation. The validity of the lumped mass model is verified through earthquake response analyses.

抄録全体を表示

This paper presents parametric studies to obtain inelastic dynamic response characteristics of torsionally unbalanced single-story models. The following four models are analyzed; 1) models with unbalanced mass, 2) models with unbalanced shear-strength, 3) models with unbalanced stiffness and 4) models with unbalanced shear-strength and stiffness. Major findings are as follows: (1) the total energy input is constant; (2) the energy input causing damages is constant if the shearstrength of models is constant; and (3) the damage concentration can be estimated by the first eigen mode and by the deviation of the yield shear force from the optimum one.

抄録全体を表示

Growth phenomena of bow-shaped deformation mode in multistory multihay weak-beam-type planar frames has been predicted by symmetry limit theory and equilibrium path bifurcation theory. To verify the validity of the theoretical prediction of the bow-shaped mode appearance, static and dynamic loading tests on the 3-story I-span miniature model frame of weak-beam-type have been carried out. In the previous article, Part I, the results of the static loading tests were presented. The prediction method for the bow-shaped mode appearance was verified and the characteristics of the collapse behavior of the frame under repeated loading were clarified. In the present article, Part II, the results of dynamic loading tests are presented. The dynamic collapse process of the frame including bow-shaped mode appearance and the drift of vibration center is examined in detail through the comparison of the results of the test specimens under various loading conditions. The validity of the two prediction methods for the bow-shaped mode appearance and the drift appearance in sway-mode vibration center is verified.

抄録全体を表示

In this paper, we discuss the applicability of life-like approach to inverse problems. Our approach is based on the concept of autonomous decentralization that is the one of characteristics in life or biological system. The approach is developed using the idea of the cell automaton. The finite element method with the relaxation technique is adopted as a solution procedure in this approach. The parameter of the inverse analysis is converted into local rules. The search algorithm for the solutions is a procedure from which the subsystem originally processes information regardless of the entire system, and the information is transmitted only to the adjacent subsystem. When the computation in the subsystem is processed, their rules are used. The inverse problems of three different following types are presented as computational example with our algorithm. 1) Minimum weight problem in 3-dimensional truss structure. 2) Self-organizing problem in 2-dimensional continuous structure. 3) Identification problem for thermal conductivity in 2-dimensional continuous body. The effectiveness and validity of our idea is shown from their numerical results. This computational method is classified into the emergent computation.

抄録全体を表示

One of techniques to put tensile stress into membrane panels of permanent membrane structures is putting tensile stress into the panel indirectly by tensing the cable after setting cable on the panel. In this case, the cable slide on the panel while external load is acting. Therefore it is important to develop analytical methods that make it possible to consider slide between cable and membrane panel. In this paper, a new analytical method, using new folding element formulated based on equivalent side tension of triangular element introduced by Tsubota et al, is proposed. In the analysis, a membrane-cable complex structure is considered as a cable net structure. As a result of applying proposed method to analysis of a sliding test and a real membrane roof structure, accuracy and applicability of this method was confirmed.

抄録全体を表示

This study proposes an alternative reduced stiffness analytical procedure using a commercially available finite element code and discusses its application to the buckling problem of single layer lattice domes under vertical loading. The present reduced stiffness analytical results are compared with a fully nonlinear finite element analysis considering initial imperfections. It is suggested that the reduced stiffness analysis provides a simple and reliable estimation for elastic and elastic-plastic design buckling loads in the lattice dome buckling problem.

抄録全体を表示

The present study discusses a proportioning method for member sections of roller supproted single layer reticulated domes. The effects of additional bending moment caused by compressive stress is noticeable to decide the sectional properties of the members. Therefore, in this study, a proportioning method based on second-order elastic analysis is used. And the usefulness of this proportioning method is discussed and verified through elasto-plastic simulation for roller supported single layer reticulated domes.

抄録全体を表示

In this paper, structural properties of truss beams with eccentric members are investigated by numerical analysis. The analytical parameters are the length and properties of the eccentric members. As a result, it is cleared that the plastic deformation behavior of such truss beams is improved, if the eccentric members yield before the critical chord member buckles. The initial stiffness and the maximum strength do not largely depend on the sectional properties of eccentric members. The slenderness ratio of the eccentric members can be a deciding factor not only in the yield load but also in the plastic deformation capacity.

抄録全体を表示

Seismic test on 12-story T-shaped coupled shear walls has been conducted under the U.S.-Japan cooperative structural research project on composite and hybrid structures. The test results showed large differences between carrying shear forces on the tensile side and the compressive side in coupled shear walls through coupling beams. In this paper, we propose macro-modelling with multi-springs for coupled walls and coupling beams, and the results of the simulation for 12-story seismic test approximate to the test results roughly. Then, by estimating lateral expansions of coupled walls, the simulation results are in good agreement with the test ones. Moreover, we propose a simplified calculation method to estimate the shear forces of coupled walls for ultimate design, though usual design is conducted without considering the axial forces of coupling beams and the lateral expansions of coupled walls.

抄録全体を表示

In this paper the results of the test, which was carried out using a total of 16 specimens of reinforced concrete columns having wing walls retrofitted with continuous fiber sheets as shear reinforcement, are described. The specimens before retrofit were designed by the old Japanese seismic code before 1971. The primary test variables were the widths of the wing walls, the kind of the fiber in the sheets and its amount as shear reinforcement. It was observed that all specimens failed in shear mode except one specimen and that the ultimate shear strengths increased linearly in proportion to the amount of the fiber as shear reinforcement. Based on the test results, an equation to evaluate the ultimate shear strengths of RC columns having wing walls retrofitted with continuous fiber sheets is proposed.

抄録全体を表示

The seismic retrofitting technique using continuous fiber sheets made of carbon, aramid or glass fibers has been applied to beams of existing reinforced concrete buildings as well as the columns. In order to improve shear capacity, the beams should be confined by wrapping in the fiber sheets. Beams, however, are generally cast with slabs, making wrapping impossible. One of the possible solutions is anchoring of the sheets using bolts and steel plates under the slab (semi-closed type strengthening). Behaviors of the semi-closed type beams, however, are not identical to those of the closed type, in which the beams are completely encased in the sheets. In this study, upper bound theorem is employed to estimate the shear strengths of the beams. Results of the analysis show a trend that strain ε_<Fc>, of the continuous fiber sheet at ultimate stage is reduced as the sheet stiffness p_<wF>E_F increases. Influences of lateral steel reinforcement ratio, geometry of the beam and concrete strength are also discussed.

抄録全体を表示

The prevailing two dimensional truss model represents experimental results well when shear reinforcement yields. The model, however, has two weak points when shear reinforcement does not yield. First, flexual deformation of shear reinforcement affect shear failure after flexual yielding. Second, sub-ties affect shear strength before flexural yielding. This paper shows an analysis considering three dimentional failure and the upper bound theorem. The effect of sub-ties on shear strength is studied. The analytical strengths agreed with the experimental ones and with the shear strength equation presented in AIJ Design Guidelines (1997). The calculated three dimensional strain distribution also agreed with the observed crack pattern inside the specimens.

抄録全体を表示

By paying attention to the fact that the transverse confinement of concrete is very useful in order to improve ductility for RC members, a new seismic retrofit technique is proposed as one of improving ductility for RC columns in this paper. The technique is an active confinement by PC bar prestressing as external hoops. These column specimens with shear span to depth ratio M/(VD)=1.5 are modeled upon the school buildings designed by the old seismic design standards before 1971 in Japan. These RC column specimens were tested under the combination of cyclic lateral forces and constant axial load. As a result, the retrofit column specimens illustrated excellent seismic performance through experimental tests, even if the RC column test specimens were likely to happen shear failure.

抄録全体を表示

In order to clarify the lateral load carrying capacity of framed shearwalls that failed in shear of their in-filled wall panel, it is necessary to investigate the compressive capacity of concrete struts restrained by both the peripheral frame and the reinforcement bars. In this paper the loading apparatus to simulate the stress condition of the shear cracked wall panel was proposed. By using the apparatus the wall panel concrete strut specimens which were reinforced by either the orthogonal grid reinforcement in longitudinal and transverse directions or that in 45-degree direction to the horizontal were tested. The shear strength of wall panel obtained by the tests agreed well with the shear strength of wall panel in framed shearwalls that failed in shear of their in-filled wall panel.

抄録全体を表示

This paper presents dynamic characteristics of newly developed lead bearing damper designed as to be installed in steel structures, on the basis of an experimental and the analytical investigations. The experimental investigation under dynamic loading condition, was carried out using a prototype specimen which consisted of lead plate, steel plate with square shaped projection (key) and holed plate. From the experimental result, a rheological model which consists of 3 elements has been proposed and the result of identification has been compared with result of equivalent linearization method. The damping characteristics of the damper have been discussed throughout both experimental and analytical results.

抄録全体を表示

In this paper the outline and test results of the experimental study about fillet welded joints using vertical connecting plates. 5 kinds of specimens concerning of this type joint were designed (see Fig.2, Fig.3) to investigate the statical characteristics of the joints. The parameters are width and thickness of vertical connecting plates, length and size of fillet weld and existence of boxing welds. It becomes clear that the maximum strength and plastic deformation ability of fillet welded joints using vertical connecting plates is little smaller than that of usual fillet welded lap joints using splice plates in case fracture mode 4 (see Fig.5) occurred. The height to thickness ratio of the connecting plate has a major influence on the maximum strength of this type of the fillet welded joints.

抄録全体を表示

Low-rise steel structures, when hit by a severe earthquake, are forced to drift beyond their elastic limits associated with local buckling of plate elements of the members. Exact formulae ruling the post-local-buckling behaviors have not been established because of non-stationary complexity. In this study, three models for the post-local-buckling hysteresis loops were proposed on the basis of experiment of box-columns with a large width-to-thickness ratio. The models were applied to response analysis of SDOF systems, from which resistances with respect to collapse and residual drift were calculated for each model. It was found that the elastic-perfectly-plastic model tends to overestimate the performance against collapse and residual drift limits, while the post-local-buckling deteriorating model induced only from monotonic load-deformation relationships provides fairly good estimations for the performance in spite of excluding the Bauschinger effect.

抄録全体を表示

This paper presents the results of full-scale tests of welded beam-to-column subassemblies having two types of improved connection details: I.e., the reduced beam section (RBS) detail recommended in the US and no weld access hole detail adopted in Japan. Both types of connection modifications successfully prevented premature fracture, and exhibited nearly identical large energy dissipation capacity, although the strength of the RBS detail is smaller than that of the no weld access hole detail. This observation is reasoned from plastic strain distributions along the beam length as well as from contributions of the beam plastic rotation to the story drift.

抄録全体を表示

In this study, the truss beam with the eccentric joints and shear panels is proposed to improve the plastic deformation capacity. Eccentric joints and shear panels are intended to disperse plastic deformation in truss beam and to transform the buckling mode. Mechanical properties of this truss beam are investigated by the loading test and the numerical analysis. As a result, initial stiffness and maximum strength of the truss beam with shear panels are equated with ones of the ordinary truss beam, and plastic deformation behavior is very stable. And shear panel form and arrangement are able to choose suitably.

抄録全体を表示

Based on the mechanical model, hysteretic characteristics of SRC beam-column joints were estimated theoretically. SRC beam-column joint was assumed to be composed of four fundamental elements; web panel, flange frame, concrete panel surrounded by flange frames and reinforced concrete panel outside steel flanges. The hysteresis loops of SRC beam-column joints were obtained by superposition of the hysteresis loop defined for each element The theoretical results gave a good agreement with the test results. Particularly, the recovering in the stiffness due to the closing of diagonal cracks of beam-column joints were predicted well by the proposed theory.

抄録全体を表示

This paper present the results of an experimental work carried out to study the elastic-plastic behavior of composite columns using core steel under constant vertical and varying horizontal loads. Area and shape of cross section of core steel and axial load ratios were selected as test parameters. Composite columns using core steel were able to hold large axial load up to rotation angle equals 5/100 rad. On the other hand reinforced concrete columns were not able to hold axial load at last. From the test results it can be thought the composite columns using core steel can prevent structural buildings under large horizontal and vertical accelerations from story failure.

抄録全体を表示

Recently concrete filled-steel tube (CFT) columns have been applied to hundreds buildings in Japan because of the high performance for seismic load. But the current design method of AIJ is difficult to be understood for structural designers and is discontinuous for slenderness. In this paper the unified and simplified design method is proposed. It is based on the concept of generalized cumulative strength of SRC for any slenderness with modification of the boundary condition of member. The accuracy has checked by reported experimental data.

抄録全体を表示