Study on adaptive‐passive eddy current pendulum tuned mass damper for wind‐induced vibration control

Tuned mass dampers (TMDs) are used to control wind‐excited responses of high‐rise building as traditional vibration control devices. A TMD will have an excellent control effect when it is well tuned. However, a traditional passive TMD is sensitive to the frequency deviation; the mistuning in frequency and damping ratio both will decrease its control effect. In the previous research, an adaptive‐passive variable pendulum TMD (APVP‐TMD) is proposed, which can identify the TMD optimal frequency and retune itself through varying its pendulum length. However, it is found that the frequency variation will change the TMD damping ratio, and an unreasonable damping ratio will lead to a decrement in the robustness of a TMD. In this study, an adaptive‐passive eddy current pendulum TMD (APEC‐PTMD) is presented, which can retune the frequency through varying the pendulum length, and retune the damping ratio through adjusting the air gap between permanent magnets and conductive plates. An adjustable eddy current pendulum TMD (PTMD) is tested, and then, a single‐degree‐of‐freedom (SDOF) primary model with an APEC‐PTMD is built, and functions of frequency and damping ratio retuning are verified. The 76‐story wind‐sensitive benchmark model is proposed in the case study. The original model without uncertainty and ±15% stiffness uncertainty models are considered, and response control effects of different controllers are compared. Results show that because the APEC‐PTMD can both retune its frequency and damping ratio; it is more robust and effective than a passive TMD. It is also found that the APEC‐PTMD has a similar control effect with the active TMD, with little power consumption and better stability.     

周期与层间位移角双约束条件下超高层结构优化设计方法

基于地震作用下层间位移角和一阶周期对构件材料成本的敏感性系数计算公式的推导,提出了双约束条件下结构优化组合排序法。结合一两层平面框架算例,分别采用建议公式和等增量敏感性分析方法计算了设计约束对构件材料成本的敏感性系数,并进行了对比;以某超高层结构为研究对象,采用提出的计算公式和组合排序法对结构进行了敏感性分析和结构优化。结果表明：采用建议的计算公式和等增量敏感性分析方法得到的敏感性系数较吻合,说明建议公式具有较高的准确性;采用组合排序法进行双约束条件下的结构优化时,当控制每组构件材料成本变化量不超过10%时,设计约束对构件材料成本的敏感性系数可认为是不变量;在初始优化阶段,设计约束改变较慢,当不敏感构件组的构件优化完成后,主要改变较敏感构件组的构件,使设计约束加速收敛至限值;优化过程中出现了最大层间位移角所在楼层交替变化的情况,可采用比规范更加严格的限值来进行结构优化,从而保证实际的设计约束条件满足规范限值要求。     

Wind‐induced vibration control of tall buildings using hybrid buckling‐restrained braces

A buckling‐restrained brace (BRB) is a system with excellent earthquake‐proof performance, but it does not dissipate energies caused by the load from weak earthquakes or winds. A hybrid BRB (H‐BRB), which improved the performance of the BRB, is a type of composite damper system consisting of a BRB and a viscoelastic damper. To explain the wind‐induced vibration control performance of H‐BRB, a 40‐story steel building was designed and used as an analysis model in this study, on the basis of the damping ratio from a structural performance test, using normal steel braces, BRB and H‐BRB. In addition, to evaluate the optimal location of H‐BRB, a time‐history analysis of four models was conducted in the study. For such time‐history analysis, wind‐load data in a 10‐year recurrence interval, which were calculated from the wind tunnel test, were used. The result of the time‐history analysis showed that H‐BRB is effective in improving both the lateral stiffness and serviceability of a building using the existing BRB. It also confirmed that it is most effective to position H‐BRBs mainly on the lower stories. Copyright © 2012 John Wiley & Sons, Ltd.     

基于等增量敏感性的高层建筑结构反向约束优化设计方法研究

以高层建筑结构为背景,提出了一种降级反向约束优化设计方法。降级反向约束优化设计方法根据工程设计习惯,按照整体、组件、构件、截面、构造的顺序逐级收紧设计约束条件,在每一轮设计中采用等增量敏感性分析方法,以最小的结构材料增量弥补本级冗余不足的设计准则,在满足规范安全性的同时,减少结构材料浪费。应用反向约束优化设计方法,对一个10层钢框架结构和一幢实际超高层钢结构进行了基于等增量敏感性的优化设计,并与正向约束优化设计方法的结果进行对比。研究结果表明,结构能够满足规范各项设计准则的要求,在充分满足安全性要求的同时,有效减少了结构材料用量,两个案例材料用料分别减少了14.2%和7.8%,且在优化过程中没有出现约束条件偏离限值的情况,提高了优化效率。     

Experimental parametric study on wind‐induced vibration control of particle tuned mass damper on a benchmark high‐rise building

A particle tuned mass damper system is an integration of tuned mass damper and particle damper. The damping performance of such device is investigated by an aero‐elastic wind tunnel test on a benchmark high‐rise building. The robustness of the system is studied by comparing the damping performance to that of a traditional tuned mass damper, and the results show that the damper has excellent and steady wind‐induced vibration control effects. Meanwhile, the parameters (filling ratio, mass ratio, and mass ratio of the container to particles), which have great influence on the vibration reduction performance of the system, are also analyzed, and it is found that the particles filling ratio plays the most important role in deciding the damping effects of the dampers. There exists an optimum filling ratio and mass ratios in which the damper can reach the best damping state. Proper parameter selections can greatly improve the damping performance.     

Multiperformance optimization design of a hybrid vibration mitigation system for super high‐rise buildings to improve earthquake resistance

A structure must meet many performance requirements to survive an earthquake. For a super high‐rise structure, the dominant control performance metric is stiffness when considering earthquake resistance because the lateral displacement of the structure often does not meet the requirements of the code even if the structure meets strength requirements. For moderate and major earthquakes, stiffness and strength play a leading role jointly. Viscous damper (VD) and buckling restraint brace (BRB) are damping devices that are commonly used in modern engineering. The efficiencies of these devices are different for different situations, and combining them can yield improved structural vibration mitigation. In this study, the performances of VD and BRB are summarized. A kind of virtual VD model with an additional damping ratio is proposed on the basis of which a VD priority placement analysis method is developed, and an optimal design is proposed. A detailed analysis of various stress states of a BRB is also performed, and a BRB arrangement method based on brace stress level analysis is proposed. The two kinds of vibration damping equipment are combined in the structure, and a practical design method for a hybrid vibration damping system is proposed. The accuracy of the proposed method is verified by considering a 10‐story plane frame. Finally, a hybrid vibration mitigation design for different objective damping ratios is performed for a super tall building project, and the design results are compared. The analysis results show that a VD can effectively increase structural damping and reduce the seismic response of the structure. A BRB is used to replace supports that experience high stress and reduce their section size, thereby reducing costs. Therefore, the proposed hybrid vibration damping structure is cost effective while providing good energy dissipation and is thus promising for engineering applications.     

Effects of tuned mass damper on correlation of wind‐induced responses and combination coefficients of equivalent static wind loads of high‐rise buildings

Tuned mass dampers (TMDs) are employed to control the wind‐induced responses of tall buildings. In the meantime, TMD may have an impact on the correlation of wind‐induced responses and combination coefficients of equivalent static wind loads (ESWLs). First, the mass matrix and stiffness matrix were extracted in this paper in accordance with the structural analysis model of two high‐rise buildings, and on that basis, the wind‐induced vibration responses analysis model with and without TMD was established. Second, the synchronous multipoint wind tunnel test to measure the pressure was performed for two high‐rise buildings, and the time history of wind‐induced vibration responses with and without TMD was studied. Finally, the impact of TMD on the correlation of wind‐induced responses and combination coefficients of ESWLs was discussed. The results of two examples suggest that after the installation of TMD, the increase of ρ_xy was 2.1% to 35.0% and ρ_yz was 2.8% to 45.6% at all wind directions for Building 1, and the increase of ρ_xy was 3.9% to 17.1% and ρ_yz was 6.8% to 38.3% for Building 2. The combination coefficients of ESWLs of two buildings were 3% to 6% larger than that of the original structure. The conclusion of this paper can be referenced by the wind resistant design of high‐rise buildings with TMD.     

Improving the wind‐induced human comfort of the Beijing Olympic Tower by a double‐stage pendulum tuned mass damper

With five sub towers and a maximum height of 246.8 m, the Beijing Olympic Tower (BOT) is a landmark of Beijing. The complex structural properties and slenderness of the BOT render it prone to wind loading. As far as the wind‐induced performance of this structure is concerned, this paper thus aims at a tuned mass damper‐based mitigation system for controlling the wind‐induced acceleration response of the BOT. To this end, the three‐dimensional wind loading of various wind directions are simulated based on the fluctuating wind force obtained by the wind tunnel test, by which the wind‐induced vibration is evaluated in the time domain by using the finite element model. A double‐stage pendulum tuned mass damper (DPTMD), which is capable of controlling the long period dynamic response and requires only a limited space of installation, is optimally designed at the upper part of the tower. Finally, the wind‐induced response of the structure with and without DPTMD is compared with respect to various wind directions and in both the time and frequency domains. The comparative results show that the wind‐induced accelerations atop the tower with the wind directions of 45, 135, 225, and 315° are larger than those with the other directions. The DPTMD significantly reduces the wind‐induced response by the maximum acceleration reduction ratio of 30.05%. Moreover, it is revealed that the control effect varies noticeably for the five sub towers, depending on the connection rigidity between Tower1 and each sub tower.     

高层建筑结构的风振阻尼控制分析与设计方法

本文首先分析了阻尼比对结构风振反应的控制效果,重点讨论了阻尼比对风振脉动增大系数的减小效果和具体计算方法,给出了便于工程实际应用的阻尼比为10%～30%的风振脉动增大系数随基本风压和结构基本周期变化的计算图表。结果表明,结构阻尼比增大,风振脉动增大系数明显减小。其次,分析了结构耗能减振系统的附加阻尼特性,给出了调频质量阻尼器(TMD)、调频液体阻尼器(TLD)和速度线性相关型耗能器附加给结构阻尼比的实用计算公式。最后给出了100层钢结构分别设置TMD和线性粘滞阻尼器的风振控制分析和设计实例。实例结果表明,两种被动阻尼控制系统对结构最大位移和最大加速度控制效果相同,可以达到40%～55%,同时说明了本文提出的方法可以方便地用于大型结构的风振阻尼控制分析和设计。     

Hybrid simulation of a tall building with a double‐decker tuned sloshing damper system under wind loads

This study presents an advanced experimental system, hardware‐in‐the‐loop (HIL), recently referred to as hybrid testing, to validate the effectiveness of a double‐decker tuned sloshing damper (TSD) system with screens applied to a recently constructed tall building. The HIL simulation facilitates a performance analysis of a combined structure‐damper system in which the nonlinear behavior of liquid motion in a TSD is physically modeled, whereas a building system under wind loads that behaves linearly is embedded virtually utilizing a computer model. The scaled model of the TSD is composed of a computer‐controlled system with a shaking table, sensors, and a real‐time communication link. The virtual building system on the computer communicates in real time with the hardware, that is, the physical model of TSD to evaluate on‐the‐fly the performance of a combined building‐TSD system. External excitation including random loading characteristics of winds, waves, or earthquakes can be implemented in HIL to observe the dynamics of the building‐damper system under a host of loading scenarios. An example of a recently completed tall reinforced concrete building with multiple TSDs placed side by side in double‐decker configuration under a suite of external loads and the proposed damping estimation procedure to evaluate the amount of auxiliary damping with TSD for ensuring the TSD design is presented. It examines the habitability of the building in winds and evaluates the effectiveness of the TSD system as well as the efficacy of the first HIL simulation for an actual tall building‐TSD system equipped with screens inside.     

Influence of soil‐structure interaction on performance of a super tall building using a new eddy‐current tuned mass damper

Tuned mass dampers (TMDs) can be used as vibration control devices to improve the vibration performance of high‐rise buildings. The Shanghai Tower (SHT) is a 632‐m high landmark building in China, featuring a new eddy‐current TMD. Special protective mechanisms have been adopted to prevent excessively large amplitude of the TMD under extreme wind or earthquake loading scenarios. This paper presents a methodology for simulating behavior of the new eddy‐current TMD that features displacement‐dependent damping behavior. The TMD model was built into the SHT finite element model to perform frequency analysis and detailed response analyses under wind and earthquake loads. Furthermore, soil‐structure interaction (SSI) effects on wind and seismic load responses of the SHT model were investigated, as SSI has a significant impact on the vibration performance of high‐rise buildings. It was found that SSI has more significant effects on acceleration response for wind loads with a short return period than for wind loads with a long return period. Some of the acceleration responses with SSI effects exceed design limits of human comfort for wind loads with shorter return periods. As to the seismic analyses, it was found that SSI slightly reduces the displacement amplitude, the damping force, and the impact force of the TMD.     

Vertical shortening prediction for super‐tall buildings considering enclosure effect and coupling effect

In this paper, the time‐dependent vertical shortening behavior of the super‐tall building is studied considering the enclosure effect and the coupling effect. A combined method to predict the overall strain of the mega section is firstly proposed by combining the B3 model and the fiber modeling approach to consider the enclosure effect of mega steel and validated by a series of in‐house experiments. An iteration method is then proposed based on the construction sequence method to consider the coupling effect of stress and strain in the vertical shortening prediction and illustrated by a super‐tall building project. Finally, the vertical shortening predictions of the super‐tall building project are compared with the field monitoring records. The results show that the strain predictions by the combined method show good agreement with experiments. Without considering the enclosure effect, the overall strain of mega section is overestimated. The coupling effect affects more on the vertical shortening of the mega column than on that of the shear wall and more on the elastic shortening than on the inelastic shortening. Without considering the coupling effect, the elastic shortening is significantly underestimated in the mega column but slightly overestimated in the shear wall. The predictions of vertical shortening in the shear wall show reasonable agreement with the measurements, whereas those in the mega column show large disagreement with the measurements, which enlightens the necessity to improve the prediction method further.     

超高层建筑黏滞阻尼器及屈曲约束支撑混合减振结构系统集成优化设计

总结分析了黏滞阻尼器(VD)与屈曲约束支撑(BRB)的基本性能,提出了附加阻尼虚拟VD模型,基于该模型发展了一种VD优先布置顺序分析方法,进而提出了基于附加阻尼虚拟VD模型的黏滞阻尼系统优化设计方法。对BRB各种应力状态进行了详细分析,提出了基于支撑应力水平分析的BRB布置方法;将两种减振装备混合布置在结构中,提出了一种实用的混合减振系统设计方法。结合一10层平面框架算例,对所提方法的准确性进行验证。最后以某超高层结构工程为例,针对不同期望阻尼比对结构进行混合减振集成优化设计,并对设计结果进行对比分析。研究结果表明,VD可以有效增大结构阻尼,降低结构地震响应,BRB用于替换应力较大支撑,可缩小支撑截面尺寸,降低结构成本。因此,混合减振结构具有高效的减振性能和良好的经济性,有较大的工程应用价值。     

Outrigger system analysis and design under time‐dependent actions for super‐tall steel buildings

The outrigger system has been widely adopted as an efficient structural lateral‐load resisting system for super‐tall buildings in recent years. Although the outrigger system has many structural advantages, it has a significant defect due to differential shortening, which cannot be neglected. Due to the shrinkage and creep of concrete, as well as the differential settlement of foundation, the shortening of the structural member is an important time‐dependent issue, which leads to additional forces in the outriggers after the lock‐in of the outriggers. As a result, it will increase the size of the structural member cross section in the design. In a real project, engineers can delay the lock‐in time of the outrigger system to release the additional forces caused by the differential shortening during the construction phase. The time‐dependent actions, such as the column shortening and the differential settlement of the foundation, were estimated. A mega frame steel structure was employed to illustrate the analysis and design of the outrigger under the time‐dependent actions. Furthermore, a simple optimal method, considering the structural stability and overall stiffness, was proposed to optimize the construction sequence of the outrigger system.     

Shaking table test and numerical simulation on vibration control effects of TMD with different mass ratios on a super high‐rise structure

In this paper, the influence of mass ratio on the vibration control effects of tuned mass damper (TMD) on a super high‐rise building has been investigated. A 1/45 scaled model of a super high‐rise building was constructed, and the TMD with the mass ratio of 0.01, 0.02, and 0.03, respectively, was suspended on the top. Shaking table test and the corresponding numerical simulation were carried out to make a further understanding of the damping mechanism. The structural performance with or without TMD was comparatively studied. The results show that larger mass ratio can improve the control effects under frequent earthquake, but the control effects increase little with the increase of mass ratio under rare earthquake due to structural damages, accompanied by stiffness degradation and nonlinear behavior of the main structure. In addition, some suggestions on the mass ratio selection are also proposed to generalize its applications.     

Three‐dimensional coupled wind‐induced vibration calculation method for super high‐rise buildings based on high‐frequency force balance technology

High‐frequency force balance test is a major technical means to evaluate the wind effect of super high‐rise buildings. Most super high‐rise buildings have the characteristic that the first two‐order modal frequencies are close, and thus, considerable modal coupling effects (MCEs) may occur under wind load. For a balance model system (BMS), MCEs increase the difficulty of correcting aerodynamic distortion signals. For the wind‐induced vibration analysis of a structural system (PSS), the calculation results of the wind‐induced response and the equivalent static wind load (ESWL) may be significantly affected without considering MCE. Based on the above‐mentioned signal distortion of BMS and the modal coupling problem of PSS, this study proposes a wind‐induced vibration calculation method for the two coupled systems (BMS and PSS). The method uses the second‐order blind identification technique based on complex modal theory and the Bayesian spectral density method considering full aerodynamic characteristics to achieve effective correction of the distortion signal in BMS. In addition, it deduces the calculation method of the wind‐induced response and ESWL considering the three‐dimensional coupled vibration of a super high‐rise building. The wind effect calculation results of a 528‐m super high‐rise building confirm the necessity and effectiveness of the proposed method.     

A generalized method for estimating drifts and drift components of tall buildings under lateral loading

A generalized method for estimating the drifts of tall buildings composed of planar moment‐resisting frames and coupled shear walls under lateral loading is presented. This method establishes the stiffness equations at the story levels by assuming that all the nodes in the same floor of a planar lateral‐force‐resisting unit have an identical lateral displacement, an identical rotation component due to the axial deformations of the columns, and an identical rotation component due to the flexural and shear deformations of the beams. By adopting this simplification, the story drifts contributed by different types of deformations, namely, the axial deformations of the columns or wall piers, the flexural and shear deformations of the beams, and the double‐curvature bending and shear deformations of the columns or wall piers, can be identified. In the formulation of the stiffness matrix, the P‐Delta effects were also incorporated. Through comparisons between the lateral displacements and story drifts computed using the proposed method and those computed using the structural analysis software Midas/Gen, the proposed method is proved to have high accuracy in estimating the drifts of tall building structures.     

Optimal design and seismic performance of Multi‐Tuned Mass Damper Inerter (MTMDI) applied to adjacent high‐rise buildings

The tuned mass damper inerter (TMDI) is an enhanced variant of the tuned mass damper (TMD) that benefits from the mass‐amplification effect of the inerter. Here, a multi‐TMDI (MTMDI) system (comprising more than one TMDI) linking two adjacent high‐rise buildings is presented as an unconventional seismic protection strategy. The relative acceleration response of the adjacent structures triggers large reaction forces of the inerter devices in the MTMDI, which in turn efficiently improve the seismic performance of the two buildings. By addressing a real project of two adjacent high‐rise buildings connected by two corridors equipped with the proposed MTMDI system, the displacement‐, interstory drift‐, and acceleration‐based parametric optimizations are separately performed by employing Nondominated Sorting Genetic Algorithm II (NSGA‐II) under 44 ground motions from the FEMA P695 far‐field record set. It is found that the frequency content of the seismic input has strong impact on the MTMDI mitigation performance. Adopting realistic mass ratio constraints, the optimally designed MTMDI outperforms both conventional MTMD and single TMDI in acceleration control, while it is not much effective in mitigating the displacement response due to the highly flexible nature of the high‐rise buildings, in contrast to other literature studies generally focused on low‐to‐medium rise buildings.     

A multi‐time‐delay compensation controller using a Takagi–Sugeno fuzzy neural network method for high‐rise buildings with an active mass damper/driver system

An active mass damper/driver (AMD) control system with a single mass has such problems as the excessive weight of the auxiliary mass and the insufficient capacity of its driving equipment. It is necessary to work through multiple subsystems to achieve effective control of high‐rise buildings. However, the time‐delay effect in each subsystem impedes its application in engineering practices. In the paper, an augmented system based on a zero‐order hold is proposed for discrete‐time systems with multiple time delays, and then the system is designed according to the compensation strategy using a classical linear quadratic regulator algorithm. After that, the sample data obtained from the zero‐order hold compensation controller is trained through a Takagi–Sugeno fuzzy neural network method. Finally, a new simplified compensation controller is designed to further shorten the time consuming calculation on the premise of guaranteeing its control effects and parameters. To verify its effectiveness, an AMD system in a high‐rise building is regarded as an example, and the proposed methodology is also applied to an experiment of a four‐story frame. Both results demonstrate that the method can enhance the performance of an AMD system with multiple time delays.     

Wind‐induced inter‐story drift analysis and equivalent static wind load for multiple targets of tall buildings

In super high‐rise buildings with varying story heights, the wind‐induced inter‐story drifts might violate the specified limit. However, these effects have seldom been concerned in wind‐induced response analysis. The theory and application of equivalent static wind load (ESWL) for wind‐induced inter‐story drifts of super high‐rise buildings were studied in this paper. A spectral decomposition method suitable for multi‐point excitation problems was firstly proposed. The formula of ESWL targeting for largest inter‐story drift was derived. For more reasonable structural design, the ESWL for multiple targets including displacement atop of building and inter‐story drifts at all story levels is put forward, in which the dominant modal inertial forces are adopted as the based load vectors. The presented methods were finally verified by its application for the wind‐induced response analysis for a tallest super tall building in Guangzhou. The researched results showed that the proposed spectral decomposition method not only has the same precision as the complete quadratic combination method but also possesses higher computation efficiency. The ESWL for multiple targets produces the same static responses for all the specified wind‐induced response, so it is much more rational for wind‐resistant structural design. Meanwhile, it is more reasonable to select the wind‐induced responses in the same direction simultaneously as the targeted values for obtaining the required ESWLs; however, the ESWL targeting for the wind‐induced responses in all degrees of freedom would generate more queer and unrealistic ESWLs distribution. Copyright © 2015 John Wiley & Sons, Ltd.