A quantity of sample members of the 18 buildings were investigated for cover concrete thickness to analyze its distribution. This paper summarizes the results of analysis of the influences of “additional cover concrete in construction phase” on the walls and undersurfaces of beams as well as the influences of the construction method by preliminary bar arrangement for the beams. “Additional cover concrete in construction phase” results in larger deviations both within each member and among members. The construction method by preliminary bar arrangement leads to smaller deviations both within each member and among members at lateral surfaces of beams.

抄録全体を表示

Recently, there were some floors which were good by previous evaluation method but which were considered to be low. Reason of low was investigated. Sensory scale about deformation of floors was made by sensory tests. But correlation between this scale and the previous physical values of floors was not enough. Factor of bad correlation was estimated as some kind of softness during foot touching. Then provisional method to measure the softness was developed. Another physical values with this method were effective to improvement of bad correlation. As a result, the reason of inferior was detected.

抄録全体を表示

Main purpose of the present study is to apply the earlier proposed failure criterion to the prediction of a failure pattern and strength of an actual historical building brick wall, and then to discuss how to express the deterioration in the criterion. Two series of experiments were carried out. In the first experiment, after conducting a series of single and double shearing test of small specimens, newly fabricated brick walls were tested to check the applicability of the proposed formula. In the second experiment, specimens from actual historical building were tested and the applicability of the formula was examined again. As a result, it was shown that the proposed failure criterion may be used to predict the failure pattern and strength to some extent when bond between a brick and jointing mortar can be well considered in the formula. The bonding rate of the presently tested historical building wall was found to be 0.6 on the average.

抄録全体を表示

This paper describes that the probabilities of exceedance is so effective to estimate safe and secure structural parameters under considering the incompatibility between the seismic performance and the wind-resistance performance. In this paper, a technique, which estimate the comprehensive safety for the earthquake loading and the wind loading based on the concept of probability, is indicated. It is tried that the structural parameters of base-isolated high-rise buildings are estimated by means of this technique. From the results, it is confirmed by estimating the probabilities of exceedance that the seismic performance and the wind-resistance performance have the incompatibility. It is also confirmed that the displacement in the base-isolator and the shear force in the first story have the incompatibility. The possibility to estimate safe and secure structural parameters for the design criteria based on the probability concept is indicated.

抄録全体を表示

This paper describes a method of numerically simulating the internal pressures of low-rise buildings with multiple rooms that are caused by the wind. The coefficient of discharge for leak flows through external and partition walls in this study is determined by using the Poiseuille's law. This study shows that the internal pressure properties obtained using the proposed simulation method correspond well to measurements taken in a wind tunnel experiment conducted using internal pressure models. The Reynolds number and discharge coefficient characteristics of leak flows through external and partition walls are analyzed based on the validity of the simulations. The mean Reynolds number value of the leak flows through external and partition walls was smaller than the transition Reynolds number for the transition from laminar to turbulent flow.

抄録全体を表示

This paper proposes a method of estimating safety, repairability and usability of a building from the viewpoint of seismic risk evaluation. The seismic risk curves regarding the loss, which have been estimated in general, were assumed to show repairability. The effects of the interrelationship between the earthquake motion and the building response characteristics on the seismic risk were analyzed in detail. In the result, it was found that the magnitudes and relative ratios of seismic risk in the structural frame, drift-sensitive and acceleration-sensitive non-structural components were affected strongly by the interrelationship. This would mean the necessity of estimating seismic risk from the various points of view. The estimation of safety and usability was easily examined, but further study is necessary. Finally, one simple example of performance-based seismic evaluation of building based on the seismic risk evaluation was shown.

抄録全体を表示

A seismic-isolation damper system consisted of a water tank and a high-porosity porous media has been proposed, and its fundamental performance is investigated by numerical computations and model experiments. A time-domain numerical model, coupled with CFD to consider the interaction between the porous media with the fluid motions, was newly developed. Shaking-table experiments with a water tank were conducted to confirm the damper's performance and to verify the validity of the numerical model. Results of the forced vibration tests showed the immobility of fluid inside the stationary porous media that highlighted an established passive damping control strategy which is based on the skyhook damper theory. The frequency-sweep studies confirmed the characteristics of the damper such as the non-increase of acceleration responses of building in the high frequency region as a basic characteristic of the skyhook damper. Numerical parametric studies with the variation of the fiber diameters of the porous media and the dimensions of water tank were also carried out to clarify the region of the immobility of fluid inside the porous media.

抄録全体を表示

A set of reduced models of structures and earthquake loads is proposed for a high-rise building under earthquake ground motions. A reduced structural model is constructed first based on an inverse problem formulation in terms of fundamental eigenfrequency and eigenmode. Then a reduced model of earthquake loads is proposed by requiring the equivalence of displacements at representative nodes in the frame model and the reduced model without inertial and damping terms. These reduced models are used in developing an optimum placement method of nonlinear dampers in high-rise buildings under earthquake ground motions. Numerical response sensitivity by the proposed reduced model is taken full advantage in the optimum placement method. The validity of the proposed method is investigated by the comparison with the results by the original full model.

抄録全体を表示

The Q value and short period source spectra of the 2009 Suruga bay earthquake (M_J6.5) and its aftershocks are estimated using spectral inversion method. Then the source model composed of two strong motion generation areas (SMGAs) are estimated using the empirical Green's function method. The estimated Q value near the source region is modeled as 30ƒ^0.64, that is, ƒ is frequency. The short period source spectrum of the main shock is the largest among previous intraslab earthquakes occurred in the Philippine Sea plate and larger than the average value for intraslab earthquakes occurred in the Pacific Sea plate. The stress drop and the total area of SMGAs are estimated to be 751 bar and 18 km², respectively. The stress drop of SMGAs is larger than the empirical scaling law for crustal earthquakes and big intraslab earthquakes in the Philippine Sea plate. The total area SMGAs is smaller than the empirical scaling law for crustal earthquakes.

抄録全体を表示

This paper aims to obtain an optimal viscous damper placement for building structures using H^∞ optimization. The H^∞ norm of the transfer function matrix is adopted as the objective function. Since it represents the magnitude of vibration transfer, one can attenuate the gain of the frequency response by minimizing this norm. The sequential quadratic programming (SQP) method is employed for optimization. The proposed method is also applicable to a various structural models as well, e.g., a bending-shear building model and a framed structure model. Numerical examples are presented to demonstrate the effectiveness of the proposed design method.

抄録全体を表示

When we study a rubber-like material based on a numerical simulation such as FEM analysis, selection of the proper hyper elastic model is important. For high damping rubber, no general constitutive law was previously established. In this paper, we propose a new elastic-plastic constitutive law for high damping rubber. The constitutive law shows the stress relaxation depending on the deformation history and the creep-like behavior though it does not depend on the time. We simulate the high damping laminated rubber bearing under horizontal biaxial loading using the elastic-plastic model to check the validity of it, and predict the behavior of high damping laminated rubber bearings under real earthquakes.

抄録全体を表示

This paper presents three dimensional behavior of Unit No.5 reactor building of the Kashiwazaki-Kariwa Nuclear Power Station subjected to the Niigataken Chuetsu-oki Earthquake in 2007, in which acceleration 4.4m/s² was recorded at the base mat. The behavior was studied for stress distribution of walls, acceleration distribution on floors and earth pressure distribution of an embedded building. The back ground of this study is increasing attention to safety of nuclear power plants subjected to large earthquakes. The damage anticipated there may be localized failure. To evaluate it, three dimensional analytical method and model were used. They were validated with 25 acceleration records of the Mid Niigata Prefecture Earthquake in 2004 before studying the three dimensional behavior.

抄録全体を表示

Lattice structures consisting of various mesh patterns show different static buckling and post-buckling behaviors even if the compression members have the same slenderness ratios. There are not sufficient studies in the literature to finding document to know the effect of these static characteristics on the seismic resistant capacity. In this paper as for plane lattice arches and double-layer cylindrical lattice roofs, the relation between dynamic collapse behavior and static collapse behavior, under excessive vertical loads, is numerically investigated to present a prediction method for the load level of dynamic collapse. The prediction method can be done with the information of load-deformation curves, natural periods and velocity response spectrum of seismic motions. The value predicted may be modified with the information of the elastic and plastic strain energies at a limit state of structures.

抄録全体を表示

In this paper, results of static loading tests on the stress transfer in mortise-tenon joints are shown. With the investigations of the experimental results, we present key requirements of a mechanical model for stress transfer in tenon joints. The model considers the discontinuity as the results of bi-axial stress state and friction by contact between tenon and mortice. Then the model can be evaluated stress transfer in the directions along fiber and perpendicular to fiber. It is necessary to recognize energy absorbing capacity and strength, inelastic mechanical model should simulate the compressive deformation inclined to the grain, the resistance of cotter and splitting. The mechanical model of main frames should be dealt with geometrically and material non-linearity incorporated with restoring force produced by rocking.

抄録全体を表示

This paper described the block shear strength of the timber for timber joints. It was found that the criteria of the block shear failures, in the timber joints, was affected by the the partial compression stresses parallel to the grain on the bearing parts. We derived the new strength calculation method of the block shear failuer of timber taken into account the partial compression stresses parallel to the grain on bearing parts or embedment. The validity of the proposed calculation method was confirmed by the experimental results.

抄録全体を表示

Lessons learned from the past earthquakes told us the importance of developing seismic performances and retrofitting of wooden houses. Especially for old wooden houses, new technologies which realize not only low cost but also easy installations are needed. In this study, a seismic retrofit method for old wooden houses using tie rods anchored in ground is proposed. The tie rods have helical wing on the edge and work as a small screwed pile. First, penetration tests were carried out to verify a workability of the tie rods. The tie rods were able to be easily installed to ground. More than 1 week later, it was verified that the tie rods were able to resist the tensile forces from 5kN to 25kN from pull-out tests. Finally, evaluation method for tensile strength of the tie rods was established based on simple mechanism and soil investigations from Swedish sounding method.

抄録全体を表示

When rigid moment resisting frames with high tension steel are subjected to the seismic force, the fracture at the ends of beam may occur and it causes the strength of frames decreased. On the other hands, the semi-rigid moment resisting frames without diaphragm with high tension steel can absorb the seismic energy at the beam-to-column connections due to its plate deformation.
This study performs cycle loading experiments to high tension steel part frames, and compares the initial rigidity and the yield strength of part frames without diaphragm with that of part frames with diaphragm. In addition, these experimental results are compared with the approximation of the reference.

抄録全体を表示

Concrete Encased Steel (CES) structural system consisting of fiber reinforced concrete (FRC) and encased steels is a new composite structural system proposed by the authors, and is being conducted continuous and comprehensive studies to make it practical. This paper discusses how to evaluate the ultimate strength of CES columns. It is revealed based on the test results that the AIJ design formulas for SRC structures can be applied for evaluating the ultimate strengths of CES columns. Furthermore, improved design formulas to estimate the ultimate strength are proposed for CES columns considering material properties.

抄録全体を表示

Being insufficient seismic capacities of the existing buildings not designed in accordance with the current code, it is politically encouraged to improve their structural properties which are specified stiffness, strength and ductility. Conventionally, bare frames of the buildings are strengthened using of steel braces or shear walls and connected by the use of many dowel anchor bolts and grouting mortar. To develop new strengthening methods without the anchor bolts, we performed a series of cyclic loading tests of R/C framed specimens retrofitted with shear walls built with cast-in-place concrete.
Two specimens exhibited high shear capacities with no less than three times of the bare frames. By taking the friction at the frame-wall joint into account, a means to evaluate the shear capacities based on the proposed resisting mechanism was presented.

抄録全体を表示

We have been measuring the performance of plural buildings by mounting optical fiber sensors capable of measuring static and dynamic displacement on some columns of plural buildings in the process of being constructed, in order to grasp and verify their performance from the difference between the performance of actual buildings and their design performance. We analyzed the results of the measurement and reached the conclusion that measurement using optical fiber sensors is applicable to (1) evaluations of the performance of buildings, structural systems, and construction quality based on the analysis of the difference between the performance of actual buildings and their design performance, (2) feedback to future design, and (3) the estimation of the degree of damage to buildings after a disaster. In this paper, we describe particularly dynamic measurement results of the measurement we have conducted on two skyscrapers whose elevational shape is irregular, or regular, and describe the utility of the measurement system to suggest, and show future prospects.

抄録全体を表示

This paper presents a experimental study on the structural behavior of H-shaped steel beams with high strength bolted joints in case of fire. Load bearing fire tests were carried out under rotational restraint conditions at the both ends of the beam in order to investigate the temperature distribution of steel beams, the rotational performance of the friction type high strength bolted joints at high temperature, and the relation of critical temperature of steel beams with joints to permanent loads. Their critical temperatures of steel beams with joints are approximated by applying the strength of joints to the simple plastic theory because the rotational capacity of beam joints is remarkably improved at elevated temperature.

抄録全体を表示