According to former research, surface crack, crack around rebar, and internal crack were observed in a reinforced concrete column with ultra high-strength concrete (UHSC) placed in winter. Following this result, effect of temperature due to hydration heat on shrinkage strain, as well as effects of dosage of expansive additive (EX) and shrinkage reducing agent (SRA) on shrinkage behavior of concrete was investigated experimentally, secondly restrained stress and resultant cracking behavior in reinforced concrete columns with ultra UHSC containing EX and SRA, as well as UHSC without EX and SRA placed in winter were investigated. As a result, 1) lower temperature of fresh concrete and higher temperature due to heat hydration enlarge the autogenous shrinkage of concrete, 2) regardless of temperature of fresh concrete and concrete history, the combined dosage of expansive additive and shrinkage reducing agent was effective in reducing shrinkage and restrained stress of concrete, 3) internal crack can not be observed in the reinforced concrete column with EX and SRA.

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Many public primary school buildings were built in high economic growth period in Japan. These buildings have some defects in building frames or concrete. These are difficult to reconstruct because of financial reasons and administrative affection so on. It is needless to say, appropriate maintenance plan and design for school buildings are necessary, also it is necessary to survey and evaluate present conditions of the buildings.
In this study, field survey was carried out on public primary school buildings built from 1970^th to the middle of 1980^th. Evaluate to these buildings for the way which based on the result of the investigation. In addition, importance is revalued to it, and influence in the repair work plan. According to these attempts, confirmed the influence of importance in the repair work plan.

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This paper presents numerical results for in-line and cross-flow oscillations of an elastically supported circular cylinder which is located in a uniform flow. The in-line oscillation of the circular cylinder has been investigated by many researchers, and the interested phenomena with respect to the oscillation have been found in a wide range of the Scruton number. For the in-line oscillation, there are two peaks of amplitudes at back and forth of velocity of a half of the critical reduced velocity. However, characteristics of excitation mechanism in the ranges in which two peaks of amplitudes appear are quite different. On the other hand, the cross-flow oscillation appears at the high reduced velocity. Therefore, we compute the in-line and cross-flow oscillations by three-dimensional simulation and the numerical results are compared with experimental

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To examine relationship between dynamic behavior of roof snow and seismic response of wooden houses by strong ground motion, the authors carried out shaking table test. The structure of one-story and flat roof with steel sheet roofing was used as the model in the test. Harmonic vibration was used as seismic wave in the test. Adfreezing of roof snow and roof surface projection that restricted roof snow sliding was recreated in the model. Relationship between sliding restriction conditions and breaking form of roof snow was observed. Sliding conditions after roof snow break were recreated in the test that changed roof surface condition and roof snow weight. Relationship between friction resistance of sliding surface and response characteristics of the model was examined by the test.
The roof snow break from weak layer and one section in wet snow might occur in strong ground motion. In the evaluation of seismic performance of wooden houses during snow season, necessity to consider the ground motion scale, sliding surface characteristics of roof snow was clarified.

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We collect resonance periods of 163 two-storied, detached wooden houses with traditional construction method by using in-situ microtremor measurements in various regions of Japan. We grasped their averaged vibration characteristics from samples in different regions with different construction ages. A difference of regional design seismic coefficient did not emerge as a difference in averaged resonance periods. Except for Sapporo region a relatively small regional variation is observed. It is estimated that an older house should have a long resonance period so should have a lower seismic capacity. On the average 30 years of age difference yields about 1.41 times of period ratio. This finding on the age degradation in seismic capacity shows good correlation to the independent results based on the damage statistics in Kobe.

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In this paper, we propose a response estimation method for seismic isolated structure with roller bearings and/or sliding bearings. The system of sliding bearing can be replaced with that of roller bearings.
Estimation with equivalent linear system is not suitable for these systems. This method is based on the theory of energy balance. The process is as follows. 1) Estimate velocity of system by spectrum intensity. 2) Calculate absorption energy. 3) Estimate displacement of system by balance of absorption energy and momentum input energy. The estimated values are well coincided with results of time history response analysis.

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The purpose of this research is to prove the equivalent linearization method on multi degree of freedom. Previous studies on this method have focused on equivalent single degree of freedom. On the other hand, very few studies have been reported on this method about multi degree of freedom. However, to develop this method, it is necessary for the design method about multi-story building. In this paper, therefore, the equivalent linearization method is developed to expand the applicable scope of the method reported by T. K. Caughey^{1) 2)}; the method based on Least-squares method. To develop this method, it is useful for the information about the mode shape of structure on the non-linear range.

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As a simple damage control structure to apply to over-track buildings with many restrictions on design and construction, response-controlled and linked structural system is effective. In order to make fixed quantity evaluation of the response reduction effective, the validity of the response evaluation by energy balance can be verified by lumped mass system model. Large effect of energy absorption is provided by the combination that is off the most suitable setting in linear range. The effect becomes small in non-linear range, but also large energy absorption is provided by using together with the vibration system including internal damping mechanism.

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This paper proposes a general method based on equivalent linearization technique using results of static pushover analysis with three dimensional frame model to predict seismic peak responses of steel structures with viscous dampers dependent on fractional power of velocity subjected to earthquakes. In this method, the equivalent damping coefficient at a given displacement is obtained by averaging damping coefficients of stationary vibration at displacement amplitude up to that displacement level. Time history response analyses were conducted to ensure accuracy of this method.

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It has been recognized that the viscoelastic damper is effective against not only seismic force but also wind force. However the effect of viscoelastic damper on the wind-induced response has not been fully comprehended. This paper discusses the wind-induced response characteristic of tall building having the viscoelastic dampers based on time-history analysis results using the fractional time-derivative model. In addition, in order to clarify the effect of frequency sensitivity of viscoelastic damper to the wind-induced response of building, time-history analysis results using Kelvin model and/or Maxwell model are compared with the fractional time-derivative model.

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Stress distribution in a tapered beam is an important issue in timber engineering, because splitting failure is possibly initiated at the taper edge. The conventional formula for the stress distribution after Maki and Kuenzi, which is adopted in current manuals of timber construction, is based on elementary mechanics assuming the Bernoulli-Euler hypothesis. However, it is not a correct solution for tapered beams, because it does not satisfy the strain compatibility as well as the boundary condition. In fact, many test data show that splitting occurs at a position apart from the maximum stress point given by the elementary solution. In this paper, exact stresses in tapered beams were derived by using stress functions in mathematical theory of elasticity. The solution was compared with those of elementary mechanics and FEM for some typical cases. It was found that the elementary solution has an unacceptable level of errors when the taper slope is greater than 0.2 or when the entire beam depth is less than three times the depth at the support.

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Effects of RC pile damage on superstructure behavior were investigated based on liquefaction tests using a large scale laminar shear box. The following conclusions were reached: (1) the superstructure moved to and fro slightly after the bending failure of pile heads occurred; (2) the superstructure moved to and fro significantly after the bending failure of pile heads and middle part of piles occurred; (3) the superstructure moved to one-side and settled with the progression of the piles failure; (4) vertical acceleration of the superstructure during an aftershock differed from that during a foreshock in a predominant period and amplitude.

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In this paper, the bending experiment on the wooden members with partial loss of sectional area was done. This bending experiment has three parameters such as the minor side of member, the direction and the length ratio of partial loss. Moreover, the influence of the partial loss of sectional area was modeled with the rotational spring, and the formula for the rotation rigidity was derived from the experimental results. The formula for the rotation rigidity was obtained from the length and the flexural rigidity in the partial loss of sectional area. Then the bending experiment on the specimens with the partial loss of sectional area to assume the post-Sashigamoi joint was done. And the effectiveness of the formula for the rotation rigidity was examined from these experimental results.

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In this paper, the results of the vibration tests concerning the scale model of the RC column under high gravity force field are shown. Due to many difficulties of shaking-table tests for the full scale structure, there have been few experiments on the collapse behavior of the structure subject to earthquake excitation. On the other hand, in the scale-down model test, it is difficult to reproduce the stress field on the scale model. In our tests, the appropriate stress field on the scale model is generated by the high gravity field using the centrifugal force. This experimental system is used, for the first time, to analyze the seismic behaviors of the superstructures, although it has been used to verify the phenomena about soils and the underground structures. The structural model is set on the shaking table located in the large centrifuge. The behaviors of two-storied structural model are simulated successfully in the experiment. The outlines of the large centrifuge and the specimen are presented. And the experimental results of earthquake collapse tests using large centrifuge machine are shown.

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The test results of the hinge isolated shear walls (called as HISS RC walls) showed slip phenomena at the wall in the large deformation range after flexural yielding. If their slip phenomena had been restricted, they, obviously, could have had stable energy absorption capacity. This paper reports the details of slip phenomena in terms of load-displacement relationships and vertical displacements at the wall bottom. Considering dowel behavior, the slip stiffness at the load zero can be modeled using pile registration formulae. The ratio of the flexural stiffness to the slip stiffness is an effective index to assess the effect of slip phenomena after flexural yielding on energy absorption characteristics.

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The author proposed a new mathematical model which predicts the ultimate behavior of two-dimensional reinforced concrete beam-column joints. The model is based on a kinematic model named nine DOF model combined with non-linear biaxial constitutive relation of concrete and steel to bear simple algebraic expressions for the ultimate moment capacity and moment at balanced failure. It is applicable to symmetric interior beam-column joints subjected four symmetric moments transmitted among the four adjacent members. This paper extends the model such that it could consider the interaction of ultimate strength and axial force, shear force transmitted from adjacent members framed into the joint as well as the amount of joint shear reinforcement in a beam-column joint designed by weak beam-strong column concept for Capacity Design. It is concluded from the theory that the factors increasing the moment capacity of beam-column joints include (1) axial force, (2) margin of moment capacity of column to beam, (3) confinement by joint shear reinforcement, (4) confinement by mid-layer bars in columns, the effect of which are followed by a simple combination rule in a simple algebraic equation form. It is also shown that the theory predicts that the factorsabove have little effect on the moment at balanced failure while (5) the concrete strength and (6) the ratio of the bar distance to the depth of member have large effect.

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This paper is a continuation of two previous papers that deals with the development of shallow-embedded column bases used in construction of steel buidlings. Behavior of exterior column bases was examined experimentally, with the slab thickness, degree of varying axial force, and reinforcement detail as test variables. It was found that both the strength and stiffness of exterior column bases differ between the positive and negative loading, and those in the negative loading are significantly smaller because the column compressive axial force decreases and the cover concrete to prevent the uplifting the base plate is absent. An analytic procedure to estimate the elastic stiffness of shallow-embedded column bases is proposed, in which resistance provided by concrete in bearing and that provided by concrete to prevent the uplifting of the steel base plate are allowed for. The procedure is found to be reasonable in light of the corresponding test results. An analytic procedure to estimate the strength of exterior column bases and its effectiveness are also presented.

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Structural rigidity and strength on the walls of aluminum honeycomb sandwich panels were investigated experimentally. Especially, the following factors which influenced on efficiency of the walls were investigated, i.e., method of fixation in top and bottom of the panels, the frame material that fixes surrounding of the panel material, method of connection unit panels that connected each other in direction of width. As a result of investigations, the following conclusions were obtained. It is enough to evaluate the rigidity and strength on safety side, if only the effect of surface plate of honeycomb panels is considered, under assumption that joint strength of top and bottom edge is enough. Framed honeycomb panels have twice stiffness to non-framed panels, but it is not appropriate to expect the effect of the strength improvement with the framed panels. Rigidity and strength of the panels can be evaluated on safety side, if the number of panels is multiplied by the performance of basic unit panel, and effect of connection unit panels in direction of width was observed.

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The deformation concentration into a relatively weak story often causes the collapse of the structure and must be carefully prevented in design practice. In this paper, we proposed a simple method to modify the member strengths in order to make the story drift angles uniform over the building height. This method is based on the optimum story shear force coefficient proposed by us in a previous paper. The applicability of the method was confirmed by numerical results of a nonlinear earthquake response analysis for four example frames.

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A shaking table test on a full-scale steel building was conducted at the E-Defense to evaluate structural and functional performance of the building under design-level ground motions and the safety margin against collapse under exceedingly large ground motions. The specimen is a 4-story moment resisting frame designed and constructed according to the current Japanese code. This paper presents the outline of the experimental plan including the design of a specimen and shaking table test results under elastic range. The elastic response characteristics regarding stiffness, restoring force and damping of the specimen are examined comparing with structural design properties.

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This paper reports the results of cyclic out-of-plane flexural experiments of brick wall specimens, reinforced by inserting stainless pins. Inserting stainless pins into unreinforced masonry walls is a technique suitable for the seismic retrofit of historic masonry constructions because of not only its lower cost and shorter construction period but also no external aesthetic alternations. Through the experiments, we examine the effectiveness of the retrofit method currently in use, present a simple design formula for evaluating the effect of the reinforcement, and determine the pattern of inserting stainless pins that has more stable reinforcing effect.

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Seismic response and crack damage of concrete filled steel tube (CFT) frames under strong ground motion are numerically analyzed and the damage ratio and damage distribution in the frame are investigated. In order to prevent the damage concentration and to distribute the damage ratio of all stories uniformly, the design condition of CFT-frame expressed by the strength ratio of concrete to steel tube is derived from the numerical results of seismic response and damage ratio distribution. CFT-frames are designed on the basis of the proposed design condition and the calculations of the seismic response and damage of them have been carried out. From the calculated results, it is ascertained that the proposed design condition of CFT-frame is useful to prevent the damage concentration in CFT-frame under strong ground motion.

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