Kazuhiko Kasai

• Tokyo Institute of Technology

Many existing high-rise buildings in Japan conform to outdated codes and require seismic retrofit to meet current standards. While installing additional seismic devices is a proven solution, these devices usually bring additional stiffness, alter dynamic characteristics of structures and exacerbate uneven stress distribution. This paper proposes a...

Frame of passively-controlled building is typically composed of steel beam, column, gusset plate and concrete slab. Its behavior is determined by the interaction of the nonlinear behavior of each component. Authors have proposed a new test method to research the behavior of frame of passively-controlled building, and carried out tests for bare gird...

In a steel structure building, it is easy to theoretically elucidate the behavior of each member, but it is difficult to evaluate the stiffness and strength at joints. Above all, in the joint where a gusset plate is attached diagonally to the frame and the dampers are connected, beams, columns, and gusset plates influence each other and show compli...

The failure of suspended ceiling system (SCS) has been one of the most widely reported seismic damage to non-structural components in buildings in recent years. In China, there are several types of SCSs applied in practice, among which the double-layer SCS with mineral wool boards is widely used in public buildings. It was found from the past earth...

Viscoelastic (VE) dampers are sensitive to temperature, excitation frequency, and strain level. As they dissipate the kinetic energy from earthquake or wind‐induced structural vibrations, their temperature increases from the heat generated, consequently softening their VE materials and lowering their dynamic mechanical properties. Temperature incre...

The optimal layout of dampers is an important part of the structural damping design process，which usually needs to be accomplished by multiple dynamic response calculations． To this end，a design procedure was proposed to determine the reasonable placement of dampers by structural static analysis，and to be able to quickly calculate the additional da...

Viscoelastic (VE) damper is a well-known passive control device in mitigating structural vibrations of high-rise buildings induced by long-period earthquakes and long-duration strong wind. Since its dynamic properties are dependent on several factors such as loading frequency and temperature, the increase of its temperature from dissipating kinetic...

The cable tray system is a kind of non-structural components used in civil and industrial buildings for the distribution of electric cables. A full-scale shaking table test on the suspended cable tray system was conducted in order to study its seismic performance. The floor response extracted by the numerical simulation and the artificially generat...

During an earthquake, the members surrounding the damper are subjected to combined bending moment and axial force produced cyclically by the actions of the damper and frame, respectively. Damper force and damper deformation have shifted phase, and the latter is in-phase with the frame story drift, which makes phase difference between the bending mo...

When a super-tall building is designed, a member-to-member model is constructed to represent the assembly of columns, beams, walls and so on. The seismic response analysis using this model is computationally expensive and outputs large amount of data. Therefore, an equivalent mass-spring system with a small number of elements and short analysis tim...

The failure of suspended ceiling systems (SCSs) has been one of the most widely reported seismic damage to non-structural components (NSCs) in buildings in recent years. To examine the seismic performance of Chinese style SCSs, the full-scale shaking table tests on Chinese style SCSs installed on a steel platform were conducted. Two specimens with...

The failure of suspended ceiling systems (SCSs) has been one of the most widely reported seismic damage to non-structural components (NSCs) in buildings in recent years. To examine the seismic performance of Chinese style SCSs, the full-scale shaking table tests on Chinese style SCSs installed on a steel platform were conducted. Two specimens with...

Recently, the heights and volumes of constructed buildings have been increasing. Similarly, bridges are being constructed with larger spans and lengths. The damage to structures such as huge buildings, bridges, or nuclear power plants can result in a substantial social impact; therefore, these structures should be designed such that they are safer...

Filtering is one of the critical steps of earthquake ground motion processing before its application to engineering practice, and high-pass filtering is particularly important due to rich contents of low frequency in ground motion signals. In particular, the impulsive properties of the ground motion recorded in near-fault zones are susceptible to t...

During earthquakes, I-shaped beams (I-beams) in a braced structure are subjected to the flexural moment synchronized with reversed axial forces transmitted from buckling restrained braces. A prior study used the modified width-thickness ratio to evaluate the rotation capacity of I-beams that failed by local buckling under alternating axial force. G...

When a super tall building is designed, a member-to-member model is constructed to represent the assembly of columns and beams. The response history analysis using member-to-member model, however, is computationally expensive and produces excessive amount of data that are not necessary at the preliminary design stage. Therefore, an equivalent mass-...

I‐shaped beams installed in a braced structure are subjected to reversed axial forces during earthquakes. Previously, we have derived the evaluation index and formulae for beams that collapsed with dominant local buckling. In this paper, we present additional experiments and numerical analyses conducted to clarify the influences of lateral‐torsiona...

Previous studies on prediction of responses of non-structural components during earthquakes based on response spectra analysis sometimes have inconsistent accuracy because of limitations on the parameters used. This paper proposes an improved simplified method for the prediction of the pseudo-spectral acceleration as well as spectral displacement o...

Monitoring of seismic response of structures has been widely employed for decades in Japan. From the structural point of view, the objectives of seismic monitoring are mainly to verify designed load assumption, evaluate seismic response and structure performance during large earthquake, detecting possible damages due to earthquake and monitoring fo...

During earthquakes, I‐shaped beams installed in a braced structure are subjected to a bending moment and compressive and tensile axial forces transmitted from the braces. The buckling behavior of a beam under the impact of an earthquake is thereby more complex than that under no axial force or constant compressive axial forces considered in previou...

In general, beams in the moment resisting steel frames are assumed axially rigid when pushover or dynamic analyses are conducted. Consequently, axial forces acting on the beams are not considered in a design procedure. However, steel beams are subjected to axial forces when frames have buckling restrained braces. The authors have confirmed the stru...

A new design method is proposed for vibration control of an inelastic multi-story frame using nonlinear viscous dampers. It determines the damper properties required to satisfy the target story drift at each story. The first step converts the frame to an equivalent SDOF (single-degree-of-freedom) model based on the static-pushover analysis. The sec...

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 amplitud...

In recent years, high-rise buildings are required to possess the higher performance for earthquakes, not only for the conventional input ground motions of L1 and L2, but also for the L3 earthquake motions (maximum considered earthquake ground motions), which are the ones with a probability of once every several thousand years, such as the long-peri...

The purpose of this paper is to carry out a response evaluation of passive control structure with viscous dampers considering its performance decrement under long-period ground motion. An analytical model of the viscous damper that considered the performance decrement caused by long-period cyclic loading was proposed in this paper, and its accuracy...

Hanging type cable rack system partially had serious damage during the Tohoku-oki Earthquake, March 11, 2011. The objective of this paper is to understand the seismic performance of the cable rack system and to propose passive control scheme for the system. Monotonic loading tests of the cable rack and shake table tests of hanged cable rack are con...

H-shaped beam installed in a braced structure are subjected to reversed axial force during the earthquake. In the previous paper, the evaluation index and formulae for beams collapse with dominant local buckling are reported. In this paper, additional experiments and numerical analyses are carried out to clarify the influences of combined (local an...

p>This paper presents a response evaluation of a Passive controlled building with viscous dampers considering its performance decrement under long-period ground motion. From the long-time sinusoidal wave test results using a full-scale viscous damper, it was shown that the performance decrement of the viscous damper was based on energetic density....

The authors conducted a series of experimental studies on the response characteristics of controlled rocking systems. This system comprises components that include a rocking frame, post-tensioning (PT) anchorages, and elasto-plastic damper, eliminating the residual deformation after the earthquake. In this paper, detailed and accurate analysis to s...

In general, beams with concrete slabs in the moment resisting steel frames are assumed to be rigid axially when pushover or dynamic analyses are conducted. Consequently, axial forces acting on the beams are not considered in a design procedure. However, steel beams are subject to axial forces when a frame has buckling restrained braces during the e...

1. Introduction Realistic three-dimensional (3-D) shake table tests using E-Defense were conducted for full-scale 5-story steel building specimens with/without dampers. Four different types of dampers, steel, viscous, oil, and viscoelastic dampers were alternatively attached to the frame, and small- to full-scale of the ground motions recorded at J...

A full-scale four-story steel building specimen was experimented using the E-Defense shake table in 2007, wherein various increasing scaled ground motions were applied until collapse. As a part of the investigation on the building response, this paper addresses the deterioration of the column subjected to simultaneous biaxial moment and axial force...

H-shaped beams installed in a braced structure are subjected to compressive and tensile forces from buckling restrained braces. In our previous paper, experiments on H-shaped beams which possess various beam sections under compressive and tensile forces were conducted. However, evaluations for the capacities of H-shaped beams under these two forces...

In this study, a new methodology for the direct displacement-based seismic control design of timber building structures with an idealized slip-hysteretic model is proposed. The structure under consideration is simulated by the shear beam model, and hysteretic dampers are used to improve the structural equivalent damping ratio and stiffness and thus...

To fulfill a displacement-based design or response prediction for nonlinear structures, the concept of equivalent linearization is usually applied, and the key issue is to derive the equivalent parameters considering the characteristics of hysteretic model, ductility level, and input ground motions. Pinching hysteretic structures subjected to dynam...

A much higher level of seismic performance is needed for supertall buildings due to increased demands for their functional continuities and the recognized needs for their continuing emergence in metropolitan areas. This paper analyzes, compares, and contrasts responses recorded during the 2011 Tohoku-oki Earthquake of different supertall buildings...

This paper presents three-dimensional nonlinear dynamic analyses of a full-scale four-story steel building tested to collapse in 2007 at the E-Defense shake-table facility in Japan, using strong ground motion. Local buckling and consequent strength deterioration of all six columns at the first-story level were observed as the main reason for the bu...

The damping modification factor (DMF) has been extensively used in earthquake engineering to describe the variation of structural responses due to varied damping ratios. It is known that DMFs are dependent not only on structural dynamic properties but also on characteristics of ground motions. DMFs regulated in current seismic codes are generally d...

In the current design code, verification of eccentricity ratio Re is required, which represents appropriate distribution of shear walls. The limitation of Re contributes to prevention of torsional vibration. However, damping performance is affected by distribution of dampers in the plan because the energy dissipation of each damper is clearly relat...

A new methodology for the direct displacement-based seismic control design of structures is presented. The main structure is simulated by bilinear hysteretic model, and the hysteretic damper is used for suppressing earthquake induced vibration. The equivalent damping ratio and stiffness are defined for inelastic structural system based on steady-st...

Composite beam has higher rigidity and strength than steel beam in the case of positive bending, and is considered to be the steel beam otherwise. Because of this, a composite beam in double curvature becomes complicated, since it consists of two portions of different length, stiffness, and strength. This paper proposes a practical analysis method...

This paper presents three‐dimensional nonlinear dynamic analyses of a full‐scale four‐story steel building tested to collapse in 2007 at the E‐Defense shake‐table facility in Japan, using strong ground motion. Local buckling and consequent strength deterioration of all six columns at the first‐story level were observed as the main reason for the bu...

Base isolation has become increasingly used not only for short buildings but also tall buildings, especially in Japan. It is recognized as an effective strategy for reducing displacement and acceleration in the superstructure. In design, rigid superstructure is generally assumed. However, for tall buildings, flexibility of the superstructure also p...

Shear panel dampers consisting of stiffeners and panels surrounded by four flanges are used as aseismic hysteretic dampers for buildings in Japan. Cracks can form easily in a shear panel damper when shear buckling occurs during the cyclic loading caused by a severe earthquake. For a relatively thin panel with a large width-to-thickness ratio, the d...

Dry cable galloping is one of hazardous phenomena that could be observed in long circular cylindrical members such as stay cables. Considerable researches have been conducted to clarify its characteristics and possible cause, but there still seem to be some uncertainties about its mechanism. This experiment was a trial to reproduce the phenomenon w...

Simplified theories are proposed for seismic response evaluation and preliminary design of "Bi-linear + Slip model" assumed wooden structures added with visco-elastic dampers. They are based on the single-degree-of-freedom (SDOF) idealization of multistory building, and produce the control performance curve expressing the peak responses as a functi...

A building with a seismic isolation system, in an earthquake, is recognized as producing substantially smaller accelerations and deformations compared with a building that use other systems. This type of system is therefore expected to better protect the building's nonstructural components, equipment, and other contents that are essential for the a...

Seismic isolation systems have been recognized for their effectiveness in protecting building and their contents. Despite costly technology, seismic isolation has been used in several countries, including Japan. Baseisolated building response could be substantially reduced, which is very favorable compared to conventional fixed-base buildings. Seve...

Seismic responses of a high-rise base-isolated building in Tokyo Institute of Technology were recorded during the 2011 Tohoku-oki earthquake. The purpose of this paper is to point out various important findings on the building responses from the recorded data, as well as to create the data base for fostering immature research areas on high-rise bas...

Viscoelastic damper dissipates energy through shear deformation of the viscoelastic material, and it causes temperature rise resulting softening of the material under long duration loading. This paper discusses properties of viscoelastic damper during long duration wind-induced vibration and presents simplified evaluation method using sinusoidal-wa...

The performance of passively-controlled building depends not only on damper but also on frame members and connections. Frame members are subjected to bending moment and shear force caused by the story drift and relatively large axial force caused by the damper force. The axial force can cause earlier yielding and possibly local buckling in the elem...

There are some types of damper to reduce the building vibration such as earthquakes. It is important for every damper to evaluate the stiffness of its component for the accurate formula of damper characteristics. This paper's Part1 showed the relationship among damping component, integrating components and supporting members in the viscous-typ...

Various types of dampers are being utilized to reduce building vibrations due to earthquakes. It is important to understand and quantify effectiveness of the damper and the building damping system, based on sound principle of mechanics. For a viscous-type (i.e., viscous or viscoelastic) damper of brace type configuration, the companion paper (Part...

Seismic responses of a high-rise base-isolated building in Tokyo Institute of Technology were recorded during the 2011 Tohoku-oki earthquake. The purpose of this paper is to point out various important findings on the building responses from the recorded data, as well as to create the data base for fostering immature research areas on high-rise bas...

A series of shake-table tests was conducted by inserting and replacing 4 different types of dampers, or by removing them in a full-scale 5-story steel frame building. The objective is to validate response-control technologies that are increasingly adopted for major Japanese buildings without being attested to-date by a major earthquake. Test result...

In order to mitigate seismic damage of timber houses, application of passive control devises is demanded. The authors have developed high performance shear walls with various types of dampers, which are called “energy dissipation walls”. For the future, new design method has to be proposed to generalize passively controlled timber structures. In th...

Application of passive dampers to timber structures is increasing with the aim of reducing seismic response including translation and torsion. The structure in such a case possesses the so-called non-proportional damping. In this paper, new system identification method considering non-proportional damping is proposed. Modal shapes including phase d...

Viscous-type dampers used for buildings can reduce building vibrations ranging from minor shaking by traffic loads to major shaking by strong earthquakes. In order to increase their efficiency, deformations of integrating component adherent to the viscous damping component must be minimized so that most deformation takes place in the latter, maximi...

抄録 Realistic 3D-shake table tests using E-Defense were conducted for full-scale 5-story building specimens with/without dampers to evaluate seismic performance, using ground motions of scales ranging from minor to catastrophic levels. The building was tested repeatedly, inserting and replacing each of 4 damper types. This paper focuses on the secon...

Shaking table tests for full-scale timber frame specimens with large stiffness eccentricity were conducted. In order to effectively reduce torsional seismic response, we proposed to add viscoelastic dampers especially in the flexible frame which has a large opening required from architectural reason. We designed passive control mechanism to add sti...

In passive controlled buildings, H-shaped beams connected to steel dampers are subjected to the cyclic axial force in addition to the flexural moment during earthquake, and then the plastic deformation capacity of H shaped beams may decrease because of compressive forces. The direction and magnitude of axial force from dampers changes with the flex...

Seismic reinforcement by Passive Control System is dynamic design, it’s a performance evaluation of buildings due to drift angle. That is why, it is difficult to evaluate with current seismic index of Structure.In this paper, we propose a method for calculating the conversion index that to evaluate the dynamic performance. In addition, considering...

Displacement mode including torsion in ultimate state is clearly related to strength balance of each frame while elastic torsional vibration is characterized by stiffness balance. Therefore, this paper presents displacement mode prediction method especially focusing on timber structure having large strength eccentricity. The method also considers v...

This paper focuses on use of supplemental stiffness and damping to reduce seismic responses of one-story torsionaly coupled structural systems having uni-axial stiffness eccentricities. Adding stiffness to minimize stiffness eccentricity can most directly reduce the torsional response, but increases translational acceleration and corresponding late...

The reports of building characteristic measurements in huge earthquakes show that viscous dampers are useful to reduce building acceleration. The formula of those damper characteristics is often relative to velocity in analysis. However the latest studies have shown that they depended on not only frequency and strain but also velocity. This means t...

An anchor-bolt-yield-type exposed column-base is typically used in low to medium-rise steel buildings. These column-base details are generally designed to consider the semi-rigid rotation spring, that caused by elastic/plastic elongation of anchor bolts. Such semirigid rotation spring stiffness (rotational rigidity) of column-base have a large effe...

Simplified theories are proposed for seismic response evaluation and preliminary design of RC building structures added with elasto-plastic dampers. They are based on the single-degree-of-freedom (SDOF) idealization of multistory building, and produce the control performance curve expressing the peak responses as a function of stiffness of all comp...

Many buildings in the Tohoku and Kanto area were strongly shaken during the Tohoku-oki earthquake on 11 March 2011. Soon after the earthquake, the Japan Society of Seismic Isolation (JSSI) established committees to investigate the performance of structures where modern seismic protection methods were used. Since response-control technologies are re...

Horizontal displacement mode including torsion in ultimate state is clearly related to strength balance of each frame while elastic torsional vibration is characterized by stiffness balance. Therefore, this paper presents horizontal displacement mode prediction method especially focusing on timber structure having large strength eccentricity. The m...

SUMMARYA series of large‐scale dynamic tests was conducted on a passively controlled five‐story steel building on the E‐Defense shaking table facility in Japan to accumulate knowledge of realistic seismic behavior of passively controlled structures. The specimen was tested by repeatedly inserting and replacing each of four damper types, that is, th...

The method proposed by the writers is based on the pioneering work of the discusser who earlier proposed a different system identification method. The validity and usefulness of the writers' method are accepted by the discusser. However, the writers' comments on other possible methods are criticized by the discusser. The present answer clarifies co...

This paper documents tests conducted to assess anchor loading characteristics and distributions over a suspended ceiling before, during, and after a series of simulated earthquakes. Miniature force-measurement devices were installed on a 4.5 by 6.5 m section of gypsum board ceiling located in a full-scale five-story building. The building was subje...

抄録 This paper proposes an accurate, member-by-member analytical model for two-story timber structures having energy dissipation walls and/or plywood shear walls. Various member joints are modeled by using nonlinear spring elements whose properties derived from numerous test results. The analyses were found to reproduce both local and global respons...

This paper discusses various effects of horizontal diaphragm flexibility on dynamic properties and seismic responses of timber structure. Equations of motion of a building with multiple discretized diaphragm elements are derived by defining reduced degrees of freedom. A method to predict dynamic properties is proposed by using the reduced degrees o...

抄録 This paper discusses various effects of diaphragm flexibility on dynamic properties and seismic responses of timber structure. Equations of motion of a building with multiple discretized diaphragm elements are derived by defining reduced degrees of freedom. A method to predict seismic responses is proposed, and example structures are used to dem...

抄録 The characteristic formula of viscous damper force is often the nonlinear viscous element model in seismic time history response analyses of structures having the dampers, but it is not always accurate. Damping force depends on properties of viscous material and its components, but the formula is not compounded from them. To make the formula mor...

抄録 A rule to predict translational and torsional seismic responses of highly damped structure is proposed. The structure is non-proportionally damped, because flexible and weak frames are provided with large dampers mitigating torsion. Steady-state theory is adopted to reduce the structure to a single-degree-of-freedom system. Peak values of the tw...

抄録 Realistic 3D-shake table tests using E-Defense were conducted for full-scale 5-story building specimens with/without dampers in order to evaluate seismic performance at ground motions of scales ranging from minor to catastrophic levels. The building was tested repeatedly, inserting and replacing each of 4 damper types. This paper focuses on the...

This paper discusses various effects of horizontal diaphragm flexibility on dynamic properties and seismic responses of timber structure. Equations of motion of a building with multiple discretized diaphragm elements are derived by defining reduced degrees of freedom. A method to predict seismic responses is proposed by using the reduced degrees of...

Simplified theories are proposed for seismic response evaluation and preliminary design of RC building structures added with visco-elastic dampers. They are based on the single-degree-of-freedom (SDOF) idealization of multistory building, and produce the control performance curve expressing the peak responses as a function of stiffness of all compo...

Many tall buildings in Tokyo metropolitan area were strongly shaken during the Great East Japan Earthquake, March 11, 2011. Most of them are less than 40 years old, and have not experienced the shaking of such a strong level. The tall buildings less than 15 years old, constructed after the 1995 Kobe Earthquake, are typically response-controlled by...

This paper discusses various effects of horizontal diaphragm flexibility on dynamic properties and seismic responses of timber structure. Equations of motion of a building with multiple discretized diaphragm elements are derived by defining reduced degrees of freedom. A method to predict seismic responses is proposed by using the reduced degrees of...

Dynamic properties of a structure tested using a shake table could be estimated correctly, if one uses an appropriate transfer function between the structural motion and table motion measured. A unique method to construct the transfer function including the effect of rocking motion of the three-dimensional (3D) shake table is proposed. By using an...

Realistic three-dimensional shake table tests using E-Defense were conducted for full-scale 5-story building specimens with/without dampers to evaluate seismic performance, under ground motions of a variety of scales ranging from minor to catastrophic levels. The building was tested repeatedly, inserting and replacing each of 4 damper types, i.e.,...

A new type of seismic resistant structural steel braced-frame system is introduced that employs controlled rocking, elastic post tensioning, and replaceable fuses to resist earthquake shaking with limited structural damage. Through the use of capacity design principles, inelastic energy dissipation is confined to replaceable fuses while the control...

In this paper, wooden frames with knee brace dampers are designed, and their performance is demonstrated. Lateral dynamic loading tests are conducted in order to examine their dynamic properties. Knee brace system can add stiffness and damping to wooden house without closing its opening, which is a great advantage to reduce torsional response of st...

Dynamic properties and seismic responses of timber structure are discussed, with focus on uni-axial stiffness eccentricity of structural walls and horizontal flexibility of floor diaphragm. The stiffness eccentricity factor Re defined in Japanese building standard law assumes rigid diaphragm, which can result in considerable error in estimations fo...

This paper proposes a time-history analysis model of high-hardness rubber that was recently developed for seismic vibration control of structures. The model combines elasto-plastic, visco-elastic, and nonlinear viscous constitutive rules. The rubber mechanical properties depend on frequency, temperature, and strain amplitude. The dependencies are e...

Dynamic properties and seismic responses of timber structure are discussed, with focus on uni-axial stiffness eccentricity of structural walls and horizontal flexibility of floor diaphragm. The stiffness eccentricity factor R e defined in Japanese building standard law assumes rigid horizontal diaphragm, which can result in considerable error in es...

The authors have conducted a series of experimental studies on the response characteristics of controlled rocking systems. This system comprises components that include a rocking frame, post-tensioning anchorages, and energy dissipation fuses, eliminating the residual deformation after the earthquake. In this paper, the shaking table test of the co...

It is necessary to clarify the characteristics of the ideal viscous fluid material to examine a characteristic model of the viscous fluid damper of the various shapes. Here the small size testing equipment was used in consideration of the steel stiffness, the work efficiency and so on. But the correct grasp of the characteristic from the measured v...

Previous studies of rocking frame systems have established their ability to resist earthquake ground motions by transforming the input energy into potential energy through uplift of the building self weight and damping out the motions through energy dissipating devices. These rocking systems are effective to minimize the residual deformation after...

A shaking table test of full-scale 4-story building was conducted at E-Defense in order to evaluate the structural and functional performances of a steel frame not only under design level but also under ground motion over design level. This paper presents the collapse behavior of a steel frame after steel members reached the maximum strength. The c...