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In evaluating the wind response of base-isolated buildings, it is important to consider not only along-wind load but also the across-wind and the torsional wind loads. It is also known that devices using lead or tin with creep potential can be considered unable to resist mean wind force. In this paper, a simple evaluation method for the wind response of base isolated buildings is proposed considering the combination of equivalent static wind loads with creep potential.

In general, eigenvalue analysis for beams considering rotatory inertia and shear deformation is not trivial, even in the case of uniform beams. In this paper, a practical method is proposed for calculating natural bending frequencies of uniform elastic beams considering rotatory inertia and shear deformation. The proposed method is based on the modified Timoshenko beam theory, which is more rigorous and realistic than the traditional Timoshenko beam theory. It is shown that the proposed method calculates the natural frequencies of an arbitrary order-vibration mode for beams of arbitrary cross-sections with a high level of accuracy, similar to numerical analysis.

In design, simple model is frequently used but this has not been done for “combination-system”. Thus, this paper proposes a method to create an equivalent shear spring model of “combination-system” consisting of its characteristic values, dampers and their support members, and frames. The parameters for the model are calculated by conducting static analysis of the building frame in four states (i.e. states N, R, pN and pR). These parameters are vital to evaluate the seismic control effect of the “combination-system”. This paper shows that the proposed model reproduces the results of time-history analysis of member models.

The purpose of this paper is to evaluate stiffness of a base-isolation layer and a super-structure of high-rise seismic isolated building from the earthquake response observation records with different amplitude levels. As a result, the stiffness of the base-isolation layer based on observation records was close to the design value. As the amplitude increased, the stiffness of the super-structure reduced – confirming the amplitude dependence of the super-structure.

An automated warehouse is a system which automatically controls the storing and shipping of a large number of cargoes in small floor spaces. In the 2011 Tohoku earthquake, many automated warehouses shut down because of the fall of stacked cargoes, and the recovery needs a long time. The importance of the seismic countermeasure preventing the fall of cargoes is noticed from the business continuity planning. The authors developed two countermeasures; one is the vibration control system and the other is the base isolation system. For developing these countermeasures, it is important to clarify the falling behaviors of cargoes. Shaking table tests were conducted for evaluating them. This paper describes the experimental results focusing on the dynamic characteristics of cargoes.

This report shows the advantage of using high-strength steels and hysteretic dampers for low- and medium-rise buildings. In this paper, the structural members are decided by the long term stress. Seismic loads are burdened with hysteretic dampers. There are two methods to increase the yield stress of columns; one is using high-strength steels, and the other is adopting larger members. Through the investigation of time history response analysis, a method using high-strength steels has high performance not only decreasing damage of frame but also increasing the equivalent damping factor than another method.

In evaluation of wind-induced responses through time-history analysis based on stationary random process, its responsive value must be dealt with numerous numbers of statistics. However, the designing value is often determined from the small number of samples because of limited time and expense in practice. Therefore, it is important and necessary to grasp dispersion of wind response from small number of samples. In this paper, the dispersion of wind forces and wind-induced responses are investigated from wind tunnel tests. Then, the influence on wind responses due to the difference in the number of samples used as an ensemble average is elucidated.

As buildings have become higher, it is likely to find the wind loads that is equal to or even greater than the design seismic loads. Therefore, it is important to estimate responses of high-rise buildings under fluctuating wind force. This paper presents contribution rate of higher mode wind response of multi-mass system for high-rise buildings by using a modal analysis in elasto range. Then, it shows that the wind responses are usually separated into the low and high frequency components, and the wind responses can be expressed as sum of them. The agreement between the predicted value based on coupling of two components and results of time-history analysis was finally confirmed.

Changes in story stiffness and natural frequency of a high-rise building on the E-defense full-scale shaking test are experimentally evaluated from small excitations to the end of the ultimate shakes, which are expected to employ as damage index for structural health monitoring. Two kinds of changes are observed similarly from both shake test and ambient vibration, which occurred in the first seismic experiences by small excitations and after the severe damage when complete ruptures on main girders appeared in ultimate shakes. The latter severe changes in story stiffness are well-simulated by using a finite element analysis for seismic design.

A series of shaking table tests on a high-rise building are conducted in order to assess effects of retrofit using steel dampers. The specimen consists of a four-story steel frame and an upper substitute layers made of concrete slabs and rubber bearings. Steel brace dampers are attached to the steel frame, and modeled steel dampers are utilized for the substitute layers. Long-period ground motions and a design ground motion are used for the tests. Total input energies of the specimen reasonably correspond to the estimations of energy spectra. The deformations of specimen are reduced especially in the portion having dampers. In the steel frame, the energy is mostly dissipated in the steel brace dampers. The capacities of the steel brace dampers are estimated about ten times larger than the seismic demand in a strong long-period ground motion.

The structural-seismic safety is evaluated by the amount of plasticity energy. The prediction method based on energy balance has been established, and this method is founded on simplified shear spring model. In case of the vibration control structure having the hysteretic dampers, the shear spring model excessively evaluates the efficiency of the vibration control of the dampers because the effective damper deformation is not considered. In this paper, the shear spring model considering the effective deformation of the hysteretic damper is made by connecting the series spring to the damper. This series spring can be obtained without the push-over analysis of the material model. In addition, the prediction method based on energy balance considering the effective damper deformation is proposed.

A series of shaking table tests on a high-rise building are conducted in order to acquire realistic data on the damage. The adopted test system consists of a lower part represented by four-story steel frame structure and an upper part simplified by substitute layers made of concrete mass and rubber bearings. In the tests using long period ground motions, the specimen is subjected to large cumulative inelastic deformations as well as large inter-story drifts. Such seismic loads are represented by total input energy to the specimen. The total input energy from each test is plotted in the corresponding energy spectrum of the input wave, indicating reasonable correlations. The beam ends dissipate ninety percent of the total input energy of the steel frame. The results characterized by input energy and its distribution suggest the adopted measuring methods reasonable. The seismic performance assessment in terms of input energy can be developed not just for a seismic design but also for damage monitoring techniques.

In long-period ground motions, high-rise buildings are subjected to large cumulative deformations as well as large story drifts. Retrofitting with dampers may be one of the most effective solutions reduce such seismic responses. This study examines the influences of steel dampers partially installed into the lower part of high-rise buildings. A series of dynamic response analyses are conducted for typical steel high-rise buildings. A long-period ground motion is adopted whose energy spectrum has a peak amplitude at three seconds, and twenty-one story buildings and thirty-five story buildings are substituted by frame models. The results show that the total energy absorption of the dampers installed into forty-percent stories can be equivalent to that of the dampers installed into the whole stories. On the other hand, the maximum drift of the story located right on the lower part having dampers would become 1.4 times larger than those of the lower part.

When a building with viscoelastic dampers is subjected to wind excitations, its dynamic properties such as vibration period and damping ratio can vary, depending on the frequency contents of the excitation. This is due to frequency sensitivity of the viscoelastic damper, and contradicts with the basis of the conventional spectral or modal analysis method using the constant dynamic properties evaluated at resonant state of the building. This paper points out the need for considering frequency sensitivity of a building when it possesses velocity-dependent dampers such as viscoelastic dampers, and proposes for the first time a new spectral or modal analysis method to predict the wind-induced response, considering the frequency sensitivity of the viscoelastic damper.

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.

This paper discusses the wind tunnel tests for a tall building model having either viscous or visco-elastic damper under the turbulent boundary layer flow. The wind tunnel tests are carried out either the across- or along-wind direction for the viscous and the visco-elastic damper systems, respectively. This wind test set-up includes a special measurement system to obtain the damper hysteetic loop, then the response property of damper and system are discussed by the referring to the obtained loop. In case of the severe wind speed, the response of visco-elastic system is smaller than the viscous system because the stiffness of visco-elastic damper contributes to the stiffness of system.