The characterization of harden concrete was analyzed by testing the weight change of water absorption. A simple testing method is submitted and discussed in this paper. As one of the test results, it was reported that the relationship between weight change (a_1) and time (t) of water absorption test would be well fitted with a_1=(α×t)/(β+t). According to the proposals, laboratory studies of a water absorption test were carried out. Test results were discussed about on evaluation of mix proportions, compressive strength and carbonation of different kinds of concrete.

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This paper is intended to study the effects of the mix proportion on the theological figures of the high-fluidity concrete using fly ash. The relationship between the mix proportion and the fluidity of the concrete was investigated regarding several experimental factors such as the kind of fly ash, the mixing ratio of fly ash to the normal cement, the mixing ratio of super plasticizer and viscosity agent, and sand aggregate ratio, etc. The rheological characteristics of the high-fluidity concrete such as plastic viscosity and yield value were measured by using the J shaped flow test. The main results are as follows. 1) In case of increasing the mixing ratio of Type I fly ash and Type II fly ash, the plastic viscosity and the yield value decrease. In case of increasing the mixing ratio of Type IV fly ash, these values increase. 2) The plastic viscosity of the concrete using Type I fly ash is smaller than that of the concrete using Type II fly ash. 3) The yield value of the concrete using Type I fly ash is nearly the same as that of the concrete using Type II fly ash.

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This paper deals with shear behaviors of reinforced masonry load bearing walls, where bond beam types of comparatively strong masonry units and mortar and concrete grouts are combined with each other under the various construction conditions. Two simple equations are clarified to be effective for predicting shear strength and rigidity before producing masonry units and assemblages.

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Based on the experimental results of strength developments of mass concrete using low-heat portland cement, rational correction of proportioning strength were investigated. The strength of concrete curing under low temperature was less than that of standard curing specimen in the same maturity. Therefore in case that concrete in structure is cured under low temperature, correction value of concrete strength for proportioning is necessary to be determined adequately. The influence of high temperature curing in an early age on the strength development of concrete was not recognized because reaching the maximum temperature of concrete took much time.

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In order to clarify seismic action to a pile foundation and stress of piles in a' soil-structure interaction system, a shaking table test on a model of superstructure, pile foundation and soil deposit was carried out. Effects of the sway and rocking motions of foundations and vibrations of the soil deposit on the pile foundation are investigated. Especially the effect of the contact condition between an embedment of foundations and surrounding soil, that is, backfill and friction at the embedment, on the stress of piles is focused. The backfill is very effective to reduce the force to piles, and the rocking motion of embedment has much influence to the bending moment of piles.

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Estimation of the fixed-base dynamic characteristics of buildings using microtremor observation has difficulty when the upper input force, e.g. wind force and pressure on the underground wall, exists. In this study, an effective method for estimating the fixed-base transfer function of the buildings having large horizontal stiffness between soil and foundation is investigated considering the influence of the upper input force as bias errors. Those errors in the estimation depend on the model parameters and the upper input force parameters. For most cases, however, the dominant frequency of the obtained transfer function well approximates the natural frequency of the system without any influence of the upper input force.

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In the authors' previous papers""31, effective methods to investigate elasto-plastic behavior of the steel structures subjected to repeated and variable loads, which are called as "critical response analysis method" and "residual stress, residual deformation analysis method", were proposed. Critical response analysis method, in which the relations between "critical loads" and "critical responses" are simultaneously obtained, is readily applied to the finite deformation problem. In this paper, in order to consider the constant amplitude loads, critical response analysis method is modified for the loads repeated along the prescribed loading path, and its formulation for the steel frame structure is presented. It is shown that the required modification of the present approach to the ordinary is to prescribe the loading path which traces the circumference of the constant magnitude domain and consider another "updated load domain" extended along the loading path. In order to verify the validity of the present method, elasto-plastic finite deformation analyses of the steel brace member subjected to repeated prescribed axial displacement are carried out, and are compared with those of the step-by-step method. Also, the influence of the loading history on the behavior of the steel brace member is discussed by comparing the results of present and ordinary critical response analysis methods.

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A method of frequency domain analysis of secondary systems is extended, and an optimization method is presented for arch-type trusses under constraints on seismic response strains. The arch and the supporting structures are regarded as secondary and primary structures, respectively, and only the arch is to be optimized. In the proposed method, eigenvalue analysis of the primary structure is to be carried out only once at the beginning of optimization. Different damping characteristics between the two parts can be easily incorporated. The accuracy and computational efficiency of the proposed method are discussed in the examples.

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The accuracy of a new straight beam element proposed by the author for the combined inelastic bending and nonuniform torsion problem is examined. A plastic hinge type formulation is employed combining the 'modified incremental stiffness method', the updated Lagrangian formulation and numerical integration about the end sections of the element. The behavior of a semi-rigid joint is also modeled as the element-end compliance. The boundary conditions of the curved beams are realized by utilizing this element-end compliance. Comparisons with existing test and numerical results show that the beam element has a sufficient accuracy for the collapse analysis of curved I-beams.

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In the static axial compressive load tests of a single pile, various methods are in existence, i.e.; the direct loading method, the method using reaction piles, the method using masses as loading reaction, the pile-toe loading method and so on. However, in these methods, influence of the loading reaction has not been compared and discussed enough. We carried out various load tests of model piles in order to examine the above problems. From these results, we could understand that the initial rigidities of compressive loads are evaluated larger and the ultimate bearing capacities are evaluated smaller in the cases of using reaction devices.

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Correlations of cone penetration resistance with physical properties of soil, SPT N-value and shear wave velocity are investigated where either the soil behaviour type index Ic proposed by Robertson, fines content or mean grain size is used as an index to specify soil types. The following conclusions are drawn: (1) The soil behaviour type index Ic shows good correlation with fines content and mean grain size. (2) The CPT-SPT resistance ratio (qt/N) varies not only with soil type but also with SPT N-value or CPT qt-value. (3) The shear wave velocity shows good correlation with the cone penetration resistance when soil behaviour type index Ic is taken into account.

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Correlations between cone penetration test (CPT) data and liquefaction resistances of sandy soils are investigated based on in situ tests and laboratory tests on high quality undisturbed samples obtained by the in situ freezing method. The CPT tests are conducted at nine sites where liquefaction resistances are available for in situ frozen samples of sands with fines contents from 0 to 30 %. The results have shown that: (1) the liquefaction resistance increases abruptly when CPT resistance exceeds a critical limit; (2) the liquefaction resistance increases with increasing fines content and soil behavior type index; and (3) the CPT vs. liquefaction resistance correlation is uniquely expressed in terms of soil behavior type index.

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The purpose of this paper is to discuss the torsional rigidity of nailed wooden members such as rafters or joists. Rotational rigidity of the nailed members which has a rectangular section can be evaluated by considering apparent withdraw rigidity of nails. The design formulae for calculating the shearing rigidity of a horizontal structural element such as floors or roofs are proposed using the rotational rigidity of nailed members. The results obtained in this paper are as follows. 1) Rotational rigidity of nailed wooden members can be evaluated by Eq. (7) with using apparent withdraw rigidity of nails Km. Km is evaluated for existing or not existing of device to prevent rotation of nailed members respectively. 2) Shearing rigidity of rafter and joist, which is concerned in the torsion of nailed members, can be evaluated with Eq. (28) and Eq. (29).

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The objectives of this study were to propose a simplified method to evaluate load defection relationship of reinforced concrete columns with side walls which could be used in the practical design procedure. The flexural and shear behaviors of columns was discussed separately and the load deflection relationship of columns was evaluated according to their failure mode. The design equation for shear strength proposed by AIJ (Design guidelines for earthquake resistant reinforced concrete buildings based on inelastic displacement concept) was applied with some modification to evaluate shear behavior of columns with irregular section. Characterized points such as flexural cracking point, yielding point, losing point of design lateral load carrying capacity and losing point of design axial load carrying capacity were considered in the flexural behavior.

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Shaking table test of a scaled model of prestressed concrete containment vessel subjected to seismic excitation in a horizontal direction and/or a vertical direction was simulated using a nonlinear finite element method. The simulation was conducted from the elastic range up to the failure taking account of rotational acceleration of the shaking table as well as horizontal acceleration. The analytical results show good correspondence with the test results except for some differences in nonlinear responses after cracking. It is concluded that the dynamic characteristics of the test model can be estimated by the finite element model with sufficient accuracy.

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Tri-axial non-linear restoring force model of reinforced concrete structures is presented in this paper. Uni-axial multi-linear restoring force model are extended to tri-axial by using an analogy to the plastic theory in this model. The restoring force characteristics of the structures are evaluated by separating into two types of characteristics. One type has energy dissipation in hysteresis loop of unloading and re-loading, and the other type has no energy dissipation in hysteresis loop. The restoring force model is able to adapt to various type of RC structural elements like columns, short columns, walls, and so forth, by connecting two types of models in series. One of the difficulties in modeling of RC structures is to express behavior of axial deformation on unloading. In this paper, a method to resolve this difficulty is presented.

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In order to investigate the effects of the compression characteristics of slit materials on the seismic behavior of R/C columns with spandrel walls, an experimental study was conducted using eight test specimens. Test results indicate that the ultimate flexural strength of the columns with structural slits become higher with the compressive strength of the slit materials, and horizontal deformation capacity of the columns with structural slits does, not decrease in comparison with the columns without any spandrel walls. The ultimate flexural strength obtained from the test could be predicted well by an existing method considering the reaction forces given by the slit material and joint steel bars.

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The purpose of this study is to understand the behavior of materials influenced by the stress-strain concentrations, which occurs at the discontinuous shapes. The effects of notch to the strength can be evaluated quantitatively by the Triaxiality Factor, which is defined by the stress distributions at the notch section. And the Triaxiality Factor can be estimated by the geometrical shape of the notch. It is possible to understand the notch effects to the strength, just only knowing the material properties and the geometrical shape.

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Steel-framed housings have a slip type force-displacement relation with low energy consumption in the slip area. The aim of this paper is to survey energy responses on Steel-Framed housing which have this type of hysteresis model under strong seismic motions. Simulated and recorded seismic waves are both used to define the influence made by their instantaneous energy input value. Seismic analyses are made by using a Steel-framed shear wall hysteresis model and by converting the building into a single as well as a multi-degree-of-freedom system. This multi-degree-of-freedom system will show the energetic properties of the building caused by the damage concentration that appears in particular story.

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In this paper, the static characteristics of WF beam to SHS column connections that beam web connected parts were reinforced were investigated by cyclic loading test. The methods of reinforcement were inserting horizontal diaphragm or vertical stiffener inside panel zone. The main parameters were type of reinforcements, width-to-thickness ratio of the column and type of web connection. The test results shows that by reinforcing of web connected parts the maximum strength and the plastic deformation ability of the beam-to-column connection are getting better. The reasons are that the out-of-plane deformation of the column is restrained enough and the bending moment carrying ratio of web connected parts becomes large by reinforcement.

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The objective of this study is to obtain the post-buckling strength of thin-plates under combined loads by FEM analysis. At first, the post-buckling behaviors of thin-plates subjected to in-plane compression and bending, in-plane compression and shear, or in-plane bending and shear are discussed. Finally the formula of post-buckling strength under combined in-plane compression, bending and shear is proposed in terms of the interaction equations. The validity of the proposed formula is examined by the further numerical analysis.

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An experimental assessment of the earthquake mitigation effect of hysteresis damper is presented in this paper. The monitoring and tests are based on a scaled 3-story steel frame model that was constructed in 1982. The earthquake response behavior of the model is investigated by use of substructure pseudo-dynamic test technique with various earthquake inputs, which were recorded by the sensors set in the site. The case studies considered in this paper offer great insight into the significant effect of hysteresis damper. Monitoring during natural earthquakes, numerical analysis based on a skeleton shift model, and pseudo-dynamic tests on the same model structure agree with each other fairly well. It is also demonstrated in this paper that the pseudo-dynamic test technique provides a satisfactory simulation of real structural response to earthquake ground motions.

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In a new structure employing reinforced concrete column-to-steel H-shaped beams connections and a new method using extended horizontal diaphragms and haunched beams to prevent brittle fracture, the high strength bolted friction joint exists substantially at the beam end. The ordinary bolted connection is designed with two connection coefficients, α_y and α_u. α_y ensures beam yielding prior to a bolt slipping with a value of 1.0. α_u ensures adequate deformability with a value of 1.25 or 1.35 for a steel grade of SS400, where strain hardening is neglected due to its location far from a column face. However, α_u should consider strain hardening as in a welded connection when a bolted connection is introduced into the critical region. Therefore, eight specimens were statically-cyclically loaded in order to clarify the applicability of the ordinary design method to such a bolted connection. The test results indicated the following, a) The same design philosophy is applicable to the bolted connection introduced into the critical position as a welded connection. However, α_y needs to be 1.06 to 1.09 of moment gradient of the connection for ensuring of a first beam yielding, and au can be set 1.35 less than the value used for the welded connection, b) The ordinary formula can predict initial stiffness, yield strength, slip strength and local buckling of the specimens. However, the calculated maximum strength is smaller than the test value.

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Middle stories in some SRC and RC buildings collapsed in the 1995 Kobe earthquake. Judging from the complete crash of the collapsed story, the building would be collapsed because it could not sustain the dead load. In this study, the collapse caused by shear failure is termed as "shear collapse" and a method of judging the collapse caused by shear was proposed. Experiments of SRC and RC column were also performed to verify the validity of the proposed method. Finally the possibility of collapse of SRC and RC buildings failed by Kobe Earthquake were judged by the proposed method and the results were compared with the real damage of the buildings.

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This paper presents a study on bearing failure of a rigid-framed joint between steel beams and reinforced concrete columns. To have a better understanding of the bearing failure, small-scaled concrete block tests were conducted under a localized bearing loading condition. The variables considered in the tests included the concrete strength, the type and amount of steel reinforcement, and the size of the loading area. The crack and failure patterns observed were similar to the ones typically seen in the beam-column joint tests. The test results indicated that all the variables substantially affected the bearing strength and deformation capability. Based on the test results, a strength model was proposed for the small-scaled" concrete blocks, consisting of three resisting elements such as direct shear resistance, and resistances due to confinement from surrounding concrete and steel reinforcement. Applying a stress block technique using the proposed model, a strength design equation was further derived for the joint bearing failure. Comparing with eighteen interior subassemblage test results, it was shown that the equation provided conservative and consistent strength estimates with proper accuracy.

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