Vibration control using ATMD and site measurements on the ...

THE STRUCTURAL DESIGN OF TALL AND SPECIAL BUILDINGSStruct. Design Tall Spec. Build. 23, 105–123 (2014)Published online 7 June 2012 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/tal.1027

Vibration control using ATMD and site measurements on theShanghai World Financial Center Tower

Xilin Lu, Peizhen Li*,†, Xianqun Guo, Weixing Shi and Jie Liu

State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China

SUMMARY

The Shanghai World Financial Center Tower is the tallest landmark building in mainland China, with aheight of 492m. In order to mitigate wind-induced vibration, a set of two identical damping deviceswas installed at the 90th floor. The damping devices are active tuned mass dampers: under wind loading,the active control feature is enabled, while the active control feature becomes disabled under earthquakeconditions, and the damping devices function as passive tuned mass dampers. The dynamic parametersof the damping devices, structural analysis results and field measurement results under different vibrationscenarios are presented in this paper. The analysis and field measurement results show that the dampingdevices performed well and had the following characteristics: they increased the damping ratio up to eighttimes in field measurements and reduced the wind acceleration response up to 60% when wind speed isbelow the designed value in the analysis. Copyright © 2012 John Wiley & Sons, Ltd.

Received 6 December 2010; Revised 25 April 2012; Accepted 17 May 2012

KEY WORDS: vibration control; site measurement; damping device; damping ratio; dynamic properties; tall buildings

1. INTRODUCTION

The Shanghai World Financial Center Tower (SWFC) is a super high-rise landmark building in Chinathat is used primarily for offices, as well as for trading centers, hotel rooms, observation decks,museum exhibits, retail centers and other public amenities. A photograph of the SWFC and ShanghaiJinmao Building is shown in Figure 1. The SWFC has 101 stories above ground with three basementlevels. The height of the building is 492m above ground level, making it the tallest structure in themainland China. The plan for the building is a 57.95m� 57.95m square. A typical floor plan is shownin Figure 2, and the vertical section is shown in Figure 3 (Robertson and See, 2007). The gross floorarea is approximately 350 000m2, including 226 900m2 for the tower, 33 370m2 for the podium and63 751m2 for the basement.The design of the SWFC complies with Chinese design codes: Code for Seismic Design of Buildings

(GB 50011-2001), Technical Specification for Concrete of Tall Buildings (JGJ 3-2002) and TechnicalSpecification for Steel Reinforced Concrete Composite Structures (JGJ 138-2001). American designcodes were also referred to when specifications were not available in the Chinese design codes: BuildingCode Requirements for Structural Concrete (ACI 318-99), Load and Resistance Factor DesignSpecification for Structural Steel Buildings (AISC-LRFD, 1999) and International Building Code(IBC-2000).The Chinese Technical Specification for the Concrete Structures of Tall Buildings (JGJ3-2002) limits

the maximum height to 190m for steel-reinforced concrete frame-reinforced concrete core walls and theaspect ratio (height/width ratio) to 7 in the Shanghai region, which is classified as a 7-degree seismic

*Correspondence to: Peizhen Li, State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University,Shanghai 200092, China.†E-mail: [email protected]

Copyright © 2012 John Wiley & Sons, Ltd.

Figure 1. A photograph of the SWFC and the Shanghai Jinmao Building.

106 X. LU ET AL.

intensity zone. If a building exceeds the above limits, additional tests and analyses should be conducted toensure the safety of the structure, including the shaking table test of the overall structure, the key jointstest, analysis of the time history of the elastic and elastoplastic dynamics of the building and a staticnonlinear analysis of the building. The height of the SWFC is 492m, and the aspect ratio is 8.49, bothof which exceed the above limits. Comfort criteria for wind loads were carefully considered in the designof the SWFC, with specifications exceeding the current Chinese design codes. The maximum accelerationfor wind loads was taken as 7–9mgal for the hotel and 9–12mgal for the office for a 1-year return period(not specified in the Chinese codes, Melbourne and Palmer, 1992) and 15–20mgal for the hotel and20–25mgal for the office for a 10-year return period. The limit in the Chinese code is 25mgal for a10-year return period. The maximum torsional velocity for wind loads was taken as 1.5mrad/s for a 1-yearreturn period and 3.0mrad/s for a 10-year return period (not specified in the Chinese codes).In the construction of the SWFC, a unique approach was employed: the horizontal loads are resisted

by three parallel structural systems, including (a) the mega-frame, consisting of the mega-columns, themega-diagonals and the belt trusses; (b) the reinforced concrete and braced steel service core; and(c) the outrigger trusses, which link the service core and the mega-frame. Because the system isrelatively new for tall buildings, such implementations warrant special study.

Copyright © 2012 John Wiley & Sons, Ltd. Struct. Design Tall Spec. Build. 23, 105–123 (2014)DOI: 10.1002/tal

Figure 2. Typical floor plan of the SWFC.

VIBRATION CONTROL USING ATMD AND SITE MEASUREMENTS ON THE SWFC 107

In order to improve the serviceability conditions for moderate wind loads with short return periods, aset of two identical active tuned mass dampers (ATMDs) was installed at the 90th floor: under windloading, the active control feature is enabled, while the active control feature becomes disabled underearthquake conditions, and the damping devices function as TMD. ATMD systems have been a popu-lar area of research, and significant progress has been made in this area. For example, ATMD in whichthe control action is achieved by a fuzzy logic controller is used to control the wind response of tallbuildings (Aldawod et al., 2001). A control strategy named sinusoidal reference strategy has beendeveloped for active control of the wind-induced vibration of super-tall buildings and was verifiedby wind tunnel tests with building models (Gu and Peng, 2002). A fuzzy hybrid control techniqueusing a semiactive tuned mass damper has been proposed for the mitigation of the wind-inducedmotion of a tall building (Kang and Kim, 2010). A hybrid mass damper system with convertible activeand passive modes has been installed on an actual slender, tall building in Chiba prefecture (Watakabeet al., 2001). A semiactive fuzzy logic-based controller is designed to attenuate the vibrations of a tallbuilding under cross-wind excitations (Zahrai and Shafieezadeh, 2009). A large-scale hybrid massdamper system was developed to reduce the tall building response during strong winds andearthquakes of up to medium strength. The system was installed in two high-rise buildings (Saitoet al., 2001). A new robust neural network methodology has been developed for the mitigation ofvibrations in a tall building under wind excitation. The building considered is a 76-story 306-mconcrete office tower controlled by an ATMD (Bani-Hani, 2007). To investigate the effectiveness ofa TMD in suppressing the wind-induced excitation motion of a tall building, aeroelastic wind tunneltests and theoretical analyses were conducted (Kim et al., 2008). High-hardness viscoelastic rubberdampers were used to upgrade both the habitability environment and the structural safety in high-risebuildings subjected to wind disturbances (Tani et al., 2009).The design complexity of the structural system of the SWFC also includes the following unique

features: (a) the dimension and cross section of the service core vary along its height for lower, middleand upper cores. Therefore, it is difficult to carry out accurate theoretical calculations on the transfereffects of the vertical and horizontal load at the transitions of the three core parts. The lower (floors1 to 59) and the middle (floors 60 to 79) service core contain a reinforced concrete services core.The upper service core is composed of structural steel with concrete encasement at the two ends ofthe core (floors 79 to 90). Steel trusses located along the long walls will reduce the structuralself-weight compared with a concrete wall. Structural steel columns and trusses at the two ends ofthe service core are encased in concrete. (b) The strengthened stories, where the belt trusses andoutrigger trusses are arranged along the height, make the vertical stiffness of the building nonuniform.The strengthened stories in the structure are regularly spaced throughout the height of the building.


Figure 3. Vertical cross section of the SWFC.

108 X. LU ET AL.

One-story high belt trusses and core transfer trusses are placed at each 12-story interval, whereas threethree-story high outrigger trusses spanning between the mega-structure columns and the corners of theconcrete service core are distributed along the height. (c) Perimeter concrete walls are located at thelower levels from floor 1 to floor 5, and mega-columns are positioned at the corners of the buildingfrom floor 6. The foundation system consists of a pile-supported mat. Piles consisting of f700mmsteel pipe piles were installed. (d) The outrigger truss system consisting of three three-story heightspace frames are regularly distributed to engage the mega-frame structure with the service core.Because of the constraints imposed by the architecture, it is impractical for outrigger trusses to passthe service core directly, and they are connected to the embedded core perimeter trusses and the



mega-columns at two ends. At the outrigger floors, a core perimeter truss is embedded in the core wallsto provide the necessary back-spans for the outrigger trusses. The corner columns of the embeddedcore perimeter truss extend throughout the height of the service core. The outrigger truss and the coreperimeter truss consist of welded structural steel sections. (e) The mega-diagonals, extending to thetop of the tower, are an important feature of the three-dimensional braced frame (Figure 3). Thesingle-diagonal system is selected for a more desirable interior space and a more aesthetically pleasingexterior facade (Lu et al., 2007; Robertson and See, 2007).The State Key Laboratory of Disaster Reduction in Civil Engineering of Tongji University was

entrusted by Shanghai World Financial Center Co., Ltd, to complete a separate series of studies onthe building structure. The studies include research on the ground motion parameters of the constructionsite, the shaking table test of the overall structure (Lu et al., 2007), the key joints test, an elastoplasticdynamics time-history analysis of the building (Lu et al., 2009), a structure vibration reduction analysiswith ATMDs and a site measurement of the structural dynamic characteristics after its completion.The structural performance of the high-rise complex building, including the dynamic properties,deformation performance and failure mechanism in seismic events, is also discussed. This paper mainlydescribes the analysis of ATMDs under various wind loadings and results from field measurements.

2. DESCRIPTION OF THE DAMPING DEVICES

The goal of damper devices is to reduce the maximum acceleration response at the top of a building toapproximately 35% of nonvibration control and to reduce the root mean square acceleration responseto approximately 40% of nonvibration control for a 1-year return period wind load (maximum windspeed at the top of the building: 26.3m/s). In addition, the damping device is locked under seismicaction; this security mechanism is designed to prevent disadvantageous effect during earthquakes.As we all know, the better location of ATMD is in the top section of the building and in the ends of

the floor plan in order to reduce the vibration and the torsion of the building. Because a big “hole”exists in the buildings from the 90th floor to 100th floor (Figure 1), there is a big space in the 90th floorand other floors do not have such big space to install the ATMD device. For this reason, the ATMDsare installed on the 90th floor, and the two damping devices are installed at the ends of the floorplan, along the Y-axis (Figures 3–4). Photograph of the damping devices are shown in Figure 5.The vibration body, whose natural period is adjusted to the fundamental period of the building(Y direction), is supported by the multisectional steel cables. With the synchronous vibration of

Figure 4. Floor plan of the 90th floor where the damping devices are located.


Figure 5. Photograph of the damping devices.

110 X. LU ET AL.

the building, the damping devices mitigate wind vibration passively by functioning as TMD. Table 1gives the basic parameters for the damping devices. Figure 6 displays the working principle of thevibration control of the TMD (Mitsubishi Heavy Industries, 2007). By using velocity sensors, theacceleration and displacement of the building and vibrating body can be estimated numerically withmeasured velocities. In addition to the passive control capability of the TMDs, the building vibrationcan be controlled actively with the measured and estimated dynamic response of the building and

Table 1. Main parameters of the damping devices.

Main parameters Damping device 1 and damping device 2

Style Screw-driven three-vibration-body two-direction active controlSize (m) 9.0� 9.0� 4.4Vibration body weight (kN) 1500Portal frame and other weight (kN) Approximately 1140Entire weight (kN) Approximately 2640Basic cycle (s) 5.2–6.5Control force (kN) 142.5Brake force (kN) 193.2Control stroke (cm) �110Travel stroke (cm) �141

Figure 6. Working principle of the vibration control of the damping devices.



vibrating body. Thus, the damping devices work as ATMD by enabling or disabling the activecontrol features. When the vibration of building is greater than 2 cm/s2 for two cycles, the dampingdevices will change from stop state to active control state (ATMD). In the active control state(ATMD), when the vibration amplitude of the vibration body is greater than 110 cm, the dampingdevices will change into passive control state (TMD). In the passive control state, when the vibrationamplitude of the vibration body is greater than 110 cm, the damping devices will be locked. In thislocked state, when the acceleration of the building is less than 30 cm/s2 over 30 s, the dampingdevices will change into passive control state (TMD). In the passive control state, when the vibrationamplitude of the vibration body is less than 30 cm over 30 s, the damping device will change intoactive control state (ATMD). In the active control state, when the vibration of the building is lessthan 2 cm/s2 over 10min, the damping devices will be locked.The damping devices consist of two parts: a multisection vibration body and a drive device. The

control force of the vibration body is obtained by the feedback motion state variables. These statevariables include the floor on which the damping devices are set up, as well as the displacement andspeed of the vibration body. The feedback gain can be obtained from the following nonlinear dynamicequation (Mitsubishi Heavy Industries, 2007):

U ¼ K1 � X1þ K2 � X2þ K3 �X1�þK4 �X2

�þUn X1;X2;X1

�;X2

�� (1)

where U is the control force, X1 is the displacement of the vibration body, X2 is the displacement of

the building, X1�

is the speed of the vibration body, X2�

is the speed of the building, K1�K4 arethe feedback gains and Un is the nonlinear control force. In this case, the nonlinear control force is verysmall and can be neglected in practice.The designed travel stroke of the damping devices is 140 cm, and the control stroke of the damping

devices is 110 cm. In addition, to avoid the excessively large displacement of the damping devicesin seismic events, the devices are locked by locking devices on the driven screw when the vibrationamplitude of vibration body exceeds 110 cm in the passive control state. If the vibration amplitudeof the vibration body exceeds 110 cm when the locking devices do not work, the limit switch willactivate, and the power will be switched off. If the control effect worsens because the control systemexperiences abnormal states, the devices will be locked by the error detection system. If there is apower failure, the devices will also be locked, and the power switch will be kept off.

3. KEY RESULTS OF THE ANALYSIS

3.1. The effect of vibration control under wind loading

In order to analyze the vibration control performance of the damping devices, the performance analysiswas conducted using the time-history curves made using the vibration spectrum of X, Y and torsionaccording to the wind direction Az= 197�, provided by wind engineering studies for the SWFC,PRC (BLWTT-SS40-2002/October 2002). The analysis employs the numerical analytical method ofNewmark-b. The maximum and root mean square values are used as the motion state variablescalculated from the state of every time step (wind speed 26.3m/s, duration 5198.40 s; wind speed34.9m/s, duration 4068.0 s; wind speed 43.7m/s, duration 3250.80 s; wind speed 46.3m/s, duration3250.80 s). The values in parentheses represent the wind speed and duration for the time histories usedin the analyses.The analytical model of the building under a wind load is shown in Figure 7 (Mitsubishi Heavy

Industries, 2007). The entire building is considered to be a single mass model with the damping deviceson the 90th floor, which is set as the reference point. In addition, two damping devices and a single massare connected horizontally with the rigid beam in the Y direction. The model is considered to have onlyone vibration degree of freedom in each direction (X and Y direction and torsion) for the analysis. Thecritical damping ratio of each vibration mode under a wind load is taken as 1% according to Chinese


Figure 7. Analytical model under a wind load.

112 X. LU ET AL.

code (MOHURD, 2002). The plastic deformation of the tall building under design wind loads is usuallysmaller than that under design seismic loads. Therefore, the damping ratio used under wind loads issmaller than that under seismic loads. Smith and Willford (2007, 2008) recommended that for buildingstaller than 250m, almost all reliable measurements show damping below 1% of the critical value. Otherresearchers also reported similar values (Li et al., 2002; Satake et al., 2003). The damping ratio ofeach vibration mode for this building through system identification from the site measurements underambient vibration is shown in Table 2. The damping ratio of each vibration mode is below or closeto 1%. The natural period of the single mass damping device has been adjusted to the same naturalperiod for the building in the Y direction. Each factor of the analytical model of the building is shownin Tables 3 and 4.The analytical results of the vibration control are shown in Tables 5–8 (Mitsubishi Heavy Industries,

2007). In the tables, under the active control state with the effect of the wind load for a 1-year returnperiod, the maximum acceleration response of the 90th floor of the building decreases to 60%, and theroot mean square of the acceleration response decreases to 55%, which meets the design requirementsfor vibration control described in Section 2. In addition, under the passive control state with the effectof the wind load of a 10-year return period, the effective direction of the wind load is slightly different,the maximum acceleration response of the building decreases to 72–79% and the root mean square ofthe acceleration response decreases to 72–74%, which also satisfies the design requirements. However,

Table 2. Natural frequency and corresponding damping ratio of the structure obtained from the sitemeasurement under ambient vibrations (ATMD off).

No. Frequency (Hz) Period (s) Damping ratio (%)

1 0.1538 6.502 0.592 0.1563 6.398 0.893 0.4785 2.090 1.084 0.5371 1.862 0.875 0.5811 1.721 1.216 0.9375 1.067 0.477 1.0303 0.971 0.578 1.3965 0.716 0.579 1.4697 0.680 0.5410 1.5332 0.652 0.6811 1.8652 0.536 0.2012 1.9287 0.518 0.2113 2.0703 0.483 0.3214 2.1582 0.463 0.3015 2.4463 0.409 0.2716 2.5146 0.398 0.3617 2.6465 0.378 0.6918 2.7148 0.368 0.4419 2.9980 0.334 0.2120 3.1982 0.313 0.1321 3.3057 0.303 0.14


Table 4. Dynamic properties of the damping devices.

First mode(Y direction)

Second mode(X direction)

Natural period (s) 6.35 6.35Effective participation weight (kN s2/m) 153.06 153.06Damping coefficient (kN s/m) 10.818 10.818

Table 5. Analytical results for the acceleration of the structure with the damping devices under a wind speedof 26.3m/s for a 1-year return period (cm/s2, rad/s2).

Nonbraking Braking Braking to nonbrakingresponse ratio

Remarks

Vibrationdirection

X Maximum 9.32 5.59 0.60 Active controlstateRMS value 2.48 1.37 0.55

Y Maximum 5.25 3.12 0.59RMS value 1.46 0.78 0.54

Torsion Maximum 0.00062 0.00057 0.93RMS value 0.00017 0.00016 0.91

Table 3. Dynamic properties of the structure used in the analytical model under a wind load.

First mode(Y direction)

Second mode(X direction)

Third mode(torsion)

Undamped natural period (s) 6.33 6.00 2.20Effective participation weight (kN s2/m) 86 377.5 84 393.1 49 130 082 kNmDamping coefficient (kN s/m) 1715 1769 2 802 770



Remarks

Vibrationdirection

X Maximum 25.31 19.88 0.79 Passive controlstateRMS value 7.08 5.23 0.74





Remarks

Vibrationdirection

X Maximum 45.78 44.50 0.97 LockedstateRMS value 17.28 16.75 0.97







Remarks

Vibrationdirection

X Maximum 71.74 69.00 0.96 LockedstateRMS value 23.99 21.71 0.90



114 X. LU ET AL.

under a locked state with the effect of wind speed for a 100- or 200-year return period, no significanteffect is observed in the maximum acceleration response (Mitsubishi Heavy Industries, 2007).

3.2. The analysis of structural seismic performance with TMD

When the active control features are disabled, the damping devices function as typical passive TMDs.The structural seismic performance of the building with the TMDs is estimated. The reduced modelwith 14 lumped masses is shown in Figure 8. The damping devices are simulated by mass-springdampers at the 91st floor. Because the damping devices are installed on the 90th floor, the parametersof the 91st floor are linearly interpolated. The floor slab of the 91st floor is treated as two rigid beamswith a length of 28m. The parameters of the model are shown in Table 9. The model is obtainedfrom the condensation of degrees of freedom through the three-dimensional modeling of the overallstructure by a finite element analysis (FEA) program. The main lateral structural systems are retained,

Figure 8. Multimass simplified model under seismic action.


Table 9. The mass distribution of the analytical model for seismic action.

Number Story Story height (m) Weight (t) Moment of inertia (t m2)

m1 Roof 51.125 780 492 307.759m2 97F 35.700 4322 3 626 339.683m3 91F 14.825 6123.899 6 415 950.390m4 88F 44.100 13 486.015 14 033 056.460m5 79F 50.330 29 951.063 34 564 648.400m6 67F 29.400 26 175.268 32 389 764.583m7 60F 21.150 17 938.530 23 839 708.992m8 55F 14.675 15 078.264 22 693 640.504m9 52F 38.125 21 270.256 32 480 739.300m10 43F 50.700 41 128.079 64 459 112.811m11 31F 14.675 29 596.987 47 283 833.420m12 28F 38.125 26 365.322 42 582 321.549m13 19F 55.020 49 794.670 80 499 758.039m14 6F 27.680 77 110.571 127 104 712.680


while the minor structural members are omitted. Therefore, only those floors are reserved, includingfloors that contain the belt trusses, the outrigger trusses and the locations where the sections of theservice core are changed; other floors are omitted. The reduced model contains 14 floors, including12 floors from the main structure and 2 floors from the capping truss portion. The first three modesof this reduced model are nearly the same as those calculated from the detailed finite element model.Two analytical models with and without damping devices are constructed. The gross mass of theoriginal structure is 3.59121� 105 tons, and the gross mass of the structure with the damping devicesis 3.59642� 105 tons. The increased mass is the weight of the two damping devices and includes thefixed weight and the movable weight. The fixed weight of each device is approximately 1140 kN, andthe movable weight is approximately 1500 kN.The FEA is performed using ANSYS© (ANSYS, Inc., Canonsburg, PA, USA). The Mass Element

in the ANSYS program is used to model the 14 lumped masses in Figure 8, and the Matrix Element isused to model the interfaces between the masses. This element is allowed to fill in the element stiffnessmatrix. The Combine Element is used to simulate the damping devices (ANSYS, 2007). This elementis shown in Figure 9, and it has longitudinal or torsional capability in one-, two- and three-dimensionalapplications. The longitudinal spring-damper option is a uniaxial tension–compression element withup to three degrees of freedom at each node: translations in the nodal X, Y and Z directions. No bendingor torsion is considered. The lock of the damping devices is ignored in the FEA. The time-historyanalysis method is used to calculate the seismic response of the structure. Four different synthesizedShanghai seismic ground motions (i.e. SHW1–SHW4) are used as seismic excitation with a peakacceleration of 220 cm/s2 (specified by Chinese seismic code). The seismic ground motion is inputin the X and Y directions separately.

Figure 9. Combine element for the TMD used in the analysis.


116 X. LU ET AL.

Tables 10 and 11 show the analysis results for the period, frequency and corresponding modalparameters with and without TMDs. The first mode of the original structure without TMDs istranslation along the Y-axis, and the corresponding period is 6.5166 s. The second mode is translationalong the X-axis, and the corresponding period is 6.4469 s. The period of the first torsional mode is2.5190 s. Consequently, the ratio of the period of the first torsional mode to the period of the firsttranslational mode is 0.387, which satisfies the requirement of the code limit (less than 0.9, specifiedin Chinese design codes: Code for Seismic Design of Buildings (GB 50011-2001)).The first mode of the structure with TMDs is translation along the Y-axis, and the corresponding

period is 6.6745 s. The second mode is translation along the X-axis, and the corresponding period is6.6247 s. The period of the first torsional mode is 2.5181 s. Consequently, the ratio of the period ofthe first torsional mode to the period of the first translational mode is 0.377, which also satisfies therequirements of the code limit. Therefore, the analysis results show that the effect of the TMD devicesis negligible with a period increase of only 2.4% with the TMDs.The length of the time history of SHW1 is 36.86 s, and the time interval is 0.01 s. The acceleration

time history and corresponding Fourier spectrum of SHW1 is given in Figure 10. The seismic groundmotion acted on the structure with or without TMDs along the X and Y directions separately. Thedamping ratio of the structure is specified as 4% according to the technical specifications for concretestructures of tall buildings in China (MOHURD, 2002). Displacement, acceleration time history andthe corresponding Fourier spectrum at the top and the 91st floor of the structure with and withoutthe TMDs under SHW1 along the X direction are given in Figures 11 and 12. Because the steel cappingtruss above floor 91 has a smaller lateral-resisting stiffness than that of the lower floors and a significantwhipping effect in response to an earthquake exists at the top of the building, the acceleration responseat the 91st floor is drastically smaller than that at the roof, as shown in Figures 11 and 12. Floordisplacement curves and interstory drift curves of the structure with and without the TMDs underSHW1 along the X direction are given in Figures 13 and 14. The service core exists from floor 1 tofloor 90, and there is a strengthened story at floor 90 (at the building height of approximately 400m).A moment steel frame consisting of the capping truss exists above floor 91. The lateral-resistingstiffness of floor 90 is larger than that of other floors, so there is a sudden drop in the interstory driftat a building height of approximately 400m, as shown in Figure 14. The maximum interstory driftsof the building are the same value (1/86) with and without TMD under SHW1 along the X direction

Table 10. Calculation result of dynamic properties of the structure with and without TMD.

Vibration modenumber

With TMD Without TMD

Period (s) Frequency(Hz)

Modalcharacteristics

Period (s) Frequency(Hz)

Modalcharacteristics

1 6.6745 0.1498 The first translationin the Y direction

6.5166 0.1534 The first translationin the Y direction

2 6.6247 0.1509 The first translationin the X direction

6.4469 0.1551 The first translationin the X direction

3 2.5181 0.3971 The first torsion 2.5190 0.3970 The first torsion

Table 11. Dynamic properties of the structure obtained from field measurements and calculations.

Direction Excitation Frequency (Hz) Period (s) Damping ratio (%)

Y 5 gal excitation at floor 90 (ATMD off) 0.1538 6.502 0.4225 gal excitation at floor 90 (ATMD on) 0.1538 6.502 3.404Ambient vibration 0.1538 6.502 0.592Calculated dynamic properties 0.1534 6.5166 —

X 5 gal excitation of floor 90 (ATMD off) 0.1563 6.398 0.4595 gal excitation at floor 90 (ATMD on) 0.1563 6.398 3.865Ambient vibration 0.1563 6.398 0.890Calculated dynamic properties 0.1551 6.4469 —


Figure 10. Acceleration time history and corresponding Fourier spectrum of SHW1 earthquake waves.


and are the same value (1/101) along the Y direction. The peak value of the base shear of the building is4.558� 105 kN without TMD and is 4.559� 105 kN with TMD under SHW1 along the X direction, andthe corresponding value along the Y direction is 5.113� 105 kN without TMD and is 5.093� 105 kNwith TMD.By comparing the seismic response of the structure under Shanghai seismic ground motion SHW1

in Figures 11–14 and Table 10, it can be seen that the response of the structure with the TMDsdecreases by less than 3%. By comparing the frequency component of the acceleration response ofthe top and the 91st floor, it can be seen that the TMD can reduce the vibration of the fundamentalmode by a very small degree. Because the fundamental mode of the structure does not dominate theseismic response, the vibration control directed toward this mode under seismic action would indeedbe fruitless. Thus, the TMD has little effect on the structure’s seismic performance.

4. SITE MEASUREMENT AND TEST RESULTS

In order to verify the analysis results, the dynamic properties of the SWFC were estimated usingacceleration measurements collected from the building. During the site test, densely distributedaccelerometer sensor networks were placed at various locations using the following two steps: (1) theaccelerometers were installed on floors 10, 50, 60, 70, 80 and 90 and (2) once the step (1) measurementswere completed, the accelerometers were moved to floors 15, 25, 55, 65, 75 and 85. In these steps, boththe ambient and free vibration responses in the X, Y and Z directions were recorded. During these tests,acceleration data were collected for 30–40min under ambient vibration conditions. The dynamicresponse range of the accelerometers used in this experiment is between 0.05Hz and 500Hz, and themaximum measurement range is 0.1 g.Forced vibration tests were also conducted using the ATMDs. Two types of tests were conducted as

follows: (a) the SWFC was forced to vibrate using one of the two ATMDs in one horizontal directionwith the amplitude of 5 gal, and then the ATMD was turned off for the free vibration response. (b) The


Figure 11. Displacement, acceleration time history and corresponding Fourier spectrum at the top ofthe structure with and without TMD under SHW1 (along the X-axis).

118 X. LU ET AL.

second test differed from the first in that while one forcing ATMD was turned off, the other ATMDwas turned on to reduce the vibration in the applicable direction.The measured data were analyzed using the peak-picking method to identify the natural frequencies,

and the damping ratios were obtained through the half-power bandwidth method (Olmos Navarreteand Roesset, 2009). System identification of the SWFC was performed for both the ambient and forcedvibration test data. In order to record the low-frequency behaviors of the structure, the accelerationresponse at various floors was sampled at rates of 10Hz and 20Hz, which resulted in a Nyquistfrequency higher than the frequencies of interest. The analytical and experimental results of thedynamic properties of the SWFC are shown in Table 11. The analytical dynamic properties areestimated using the reduced 14 lumped mass model described in Section 3. Table 11 shows that thenatural frequencies estimated in the analytical and experimental studies are almost identical, with0.3% error. The estimated natural frequencies and corresponding damping ratios for the ambientvibration data are also summarized in Table 2 with the first 21st mode frequencies. In the test in whichthe structure was forced to vibrate by an ATMD, because the mode of the ATMD is tuned to the


Figure 12. Displacement, acceleration time history and corresponding Fourier spectrum at the 91stfloor of the structure with and without TMD under SHW1 (along the X-axis).


fundamental mode of the structure, only the fundamental mode of the structure is excited.Consequently, in forced vibration tests, only the fundamental mode can be identified. In the ambientvibration tests, all fundamental modes can be identified.The acceleration time history of the 90th floor in the X and Y directions with and without active

vibration control from the two types of forced vibration tests at an amplitude of 5 gal is shown inFigures 15, 16. There is a pulse when the ATMD is started, which caused the maximum accelerationsto not be exactly equal to 5 gal in these figures. In some case, the maximum acceleration is greater than5 gal, and in other cases, the maximum acceleration is smaller than 5 gal. For the ATMD, it wasobserved that structural vibration is mitigated rapidly. The damping ratio for the first mode (in the Ydirection) without active vibration control is 0.422%, while the value changes to 3.404% with activevibration control. The damping ratio for the second mode (along the X direction) without activevibration control is 0.459%, while the value increases to 3.865% with active vibration control. Thedamping ratio with vibration control devices increases by eight times.


Figure 13. Floor displacement curves of the structure with and without TMD under SHW1 (alongthe X-axis).

Figure 14. Interstory drifts curves of the structure with and without TMDunder SHW1 (along the X-axis).

120 X. LU ET AL.


Figure 15. Acceleration time history of the 90th floor along the Y-axis under forced vibration at anamplitude of 5 gal.

Figure 16. Acceleration time history of the 90th floor along the X-axis under forced vibration at anamplitude of 5 gal.


5. CONCLUSION

The SWFC is a super high-rise landmark building in China. In order to mitigate wind-induced vibra-tion, a set of two identical damping devices was installed on the 90th floor. The damping devices areATMD: under wind loading, the active control feature is enabled, while under earthquake condition,the active control feature becomes disabled, and the damping devices function as TMD. The dynamiccharacteristics of the damping devices installed in the SWFC, the structural analysis results and the sitevibration measurement results were discussed. There are some conclusions drawn from the study:(a) under the wind load for a 1-year return period, the damping devices work in active control state.The maximum acceleration response of the 90th floor of the building decreases to 60%, and the rootmean square of the acceleration response decreases to 55%, which meets the design requirementsfor vibration control. (b) The analysis results show that the effect of the TMD devices is negligible withthe period of the structure increase of only 2.4% with the TMDs and the response of the structure withthe TMDs decreases by less than 3%. The results show that no significant effects from the dampingdevices are observed during seismic simulations. (c) The site measurement results show that thestructural vibration is mitigated rapidly with active vibration control and the damping ratio with activevibration control devices increases by eight times.The analysis and field measurement results show that the damping devices performed well. It tells us

that the ATMD can be used to control the wind-induced vibration of such super-tall buildings effect-ively while without significant effects under seismic.


122 X. LU ET AL.

NOMENCLATURE

The following symbols are used in this paper.

U

Copyright ©

control force
X1 displacement of the vibration body X2� displacement of the building X1 speed of the vibration body X2�
speed of the building
K1�K4 feedback gain Un nonlinear control force Az wind direction
ACKNOWLEDGEMENTS

This project was partially supported by the Ministry of Science and Technology of China (grant no.SLDRCE 09-B-09), the project (grant no. 51178349) and the key project (grant nos 90815029 and51021140006) of the National Natural Science Foundation of China. The work is also supported bythe Fundamental Research Funds for the Central Universities and Kwang-Hua Fund for the Collegeof Civil Engineering, Tongji University.

REFERENCES

Aldawod M, Samali B, Naghdy F, Kwok KCS. 2001. Active control of along wind response of tall building using a fuzzycontroller. Engineering Structures 23(11): 1512–1522.

ANSYS Inc. ANSYS Element Reference. 2007.Bani-Hani KA. 2007. Vibration control of wind-induced response of tall buildings with an active tuned mass damper using

neural networks. Structural Control and Health Monitoring 14(1): 83–108.Gu M, Peng FJ 2002. An experimental study of active control of wind-induced vibration of super-tall buildings. Journal of Wind

Engineering and Industrial Aerodynamics 90(12–15): 1919–1931.Kang J, Kim HS. 2010. Fuzzy hybrid control of a wind-excited tall building. Structural Engineering and Mechanics 36(3): 381–399.Kim YM, You KP, Kim HY. 2008. Wind-induced excitation control of a tall building with tuned mass dampers. The Structural

Design of Tall and Special Buildings 17(3): 669–682.Li QS, Yang K, Zhang N, Wong CK, Jeary AP. 2002. Field measurement of amplitude dependent damping in a 79-storey tall

building and its effects on the structural dynamic responses. The Structural design of tall buildings 11: 129–153.Lu XL, Zhu JJ, Zou Y. 2009. Study on performance-based seismic design of Shanghai World Financial Center Tower. Journal of

Earthquake and Tsunami 3(4): 273–284.Lu XL, Zou Y, Lu WS, Zhao B. 2007. Shaking table model test on Shanghai World Financial Center Tower. Earthquake

Engineering and Structural Dynamics 36(4): 439–457.Melbourne WH, Palmer TR. 1992. Accelerations and comfort criteria for buildings undergoing complex motions. Journal of

Wind Engineering and Industrial Aerodynamics (41–42): 105–116.Ministry of Housing and Urban–Rural Development of the People’s Republic of China (MOHURD). 2002. Technical specification

for concrete structures of tall building (JGJ 3-2002), China architecture & building press. (in Chinese)Mitsubishi Heavy Industries, Ltd. 2007. Technical consulting conference data of the damping devices set up in Shanghai World

Financial Center Tower. (in Chinese and in Japanese)Olmos Navarrete BA, Roesset JM. 2009. Analytical evaluation of the accuracy of the half-power bandwidth method to estimate

damping ratios in a structure. 4th International Conference on Structural Health Monitoring on Intelligent Infrastructure(SHMII-4), 22–24 July, Zurich, Switzerland.

Robertson LE, See ST. 2007. The Shanghai World Financial Center: welding brilliant architecture to imaginative engineering.Structure Magazine, June: 32–35.

Saito T, Shiba K, Tamura K. 2001. Vibration control characteristics of a hybrid mass damper system installed in tall buildings.Earthquake Engineering and Structural Dynamics 30(11): 1677–1696.

Satake N, Suda K, Arakawa T, Sasaki A, Tamura Y. 2003. Damping evaluation using full-scale data of buildings in Japan. ASCEJournal of Structural Engineering 129(4): 470–477.

Smith RJ, Willford MR. 2007. The damped outrigger concept for tall buildings. The Structural Design of Tall and SpecialBuildings 16(4): 501–517.

Smith R, Willford M. 2008. Damping in tall buildings – uncertainties and solutions. 17th Congress of IABSE, Chicago.Tani T, Yoshitomi S, Tsuji M, Takewaki I. 2009. High-performance control of wind-induced vibration of high-rise building via

innovative high-hardness rubber damper. The Structural Design of Tall and Special Buildings 18(7): 705–728.

2012 John Wiley & Sons, Ltd. Struct. Design Tall Spec. Build. 23, 105–123 (2014)DOI: 10.1002/tal


Watakabe M, Tohdo M, Chiba O, Izumi N, Ebisawa H, Fujita T. 2001. Response control performance of a hybrid mass damperapplied to a tall building. Earthquake Engineering and Structural Dynamics 30(11):1655–1676.

Zahrai SM, Shafieezadeh A. 2009. Semi-active control of the wind-excited benchmark tall building using a fuzzy controller.Iranian Journal of Science and Technology Transaction B-Engineering 33(B1): 1–14.

AUTHORS’ BIOGRAPHIES

Xilin Lu is a professor at State Key Laboratory of Disaster Reduction in Civil Engineering, TongjiUniversity. He is the vice head of the State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University, from 1996. He is also the chief editor of the journal of “The Structural Design ofTall and Special Buildings” from 2012. His professional expertise are in the following fields: passivestructural control research and application, seismic resistance of high-rise building structures,nonlinear analysis of reinforced concrete structures and seismic behavior of precast concrete structures.

Peizhen Li is an associate professor at State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University. His professional expertises are in the fields of structural engineering and earthquakeengineering.

Xianqun Guo is a part-time professor at State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University. His professional expertise is in the field of structural engineering.

Weixing Shi is a professor at State Key Laboratory of Disaster Reduction in Civil Engineering, TongjiUniversity. His professional expertises are in the fields of structural engineering and earthquakeengineering.

Jie Liu has a master’s degree in Structure Engineering from Tongji University (Shanghai 2005). She isnow member of Shanghai Xian Dai Architectural Design (Group) Co., Ltd. Her expertise is in the fieldof structural design and analysis.


Vibration control using ATMD and site measurements on the ...

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