Performance‐based design with semi‐active structural control technique

The recent spate of large earthquakes has triggered diverse performance requirements for structures. This has led to increasing worldwide interest in performance‐based design methods. To establish such methods, however, it is necessary to evaluate structure conditions after defining the loads, and this is difficult to accomplish. On the other hand, there has been steady progress on research and development of structural control techniques for improving structural performance. These technological innovations need to be rationally incorporated into structural design. In particular, semi‐active structural control techniques are effective in improving structural performance during large earthquakes. By effectively incorporating them into the design, it is possible to meet the various structural performance requirements. This paper first outlines the various structural control methods and focuses on the semi‐active structural control technique as the main topic. It then describes an example to verify the effectiveness of the semi‐active structural control technique in high‐rise buildings. Copyright © 2001 John Wiley & Sons, Ltd.     

Earthquake response of elastic SDF systems with non‐linear fluid viscous dampers

The steady‐forced and earthquake responses of SDF systems with a non‐linear fluid viscous damper (FVD) are investigated. The energy dissipation capacity of the FVD is characterized by the supplemental damping ratio ζsd and its non‐linearity by a parameter designated α. It is found that the structural response is most effectively investigated in terms of ζ_sd and α because (1) these two parameters are dimensionless and independent, and (2) the structural response varies linearly with the excitation intensity. Damper non‐linearity has essentially no influence on the peak response of systems in the velocity‐sensitive spectral region, but differences up to 14% were observed in the other spectral regions. The structural deformation is reduced by up to 25% when ζ_sd= 5%; and by up to 60% when ζ_sd= 30%. Non‐linear FVDs are advantageous because they achieve essentially the same reduction in system responses but with a significantly reduced damper force. For practical applications, a procedure is presented to estimate the design values of structural deformation and forces for a system with non‐linear FVD directly from the design spectrum. It is demonstrated that the earthquake‐induced force in a non‐linear FVD can be estimated from the damper force in a corresponding system with linear FVD, its peak deformation, and peak relative velocity; however, the relative velocity should not be approximated by the pseudo‐velocity as this approximation introduces a large error in the damper force. Finally, a procedure is presented to determine the non‐linear damper properties necessary to limit the structural deformation to some design value or the structural capacity for a given design spectrum. Copyright © 2002 John Wiley & Sons, Ltd.     

Multiobjective optimal FLC driven hybrid mass damper system for torsionally coupled,seismically excited structures

In most of the research work on structural vibration control only two‐dimensional plane structural modelling has been considered, although only a few practical building structures can be modelled as planar structures. Therefore, these methods are not directly applicable to the majority of the practical building structures. This paper discusses the design of a multiobjective optimal fuzzy logic controller (FLC) driven hybrid mass damper (HMD) system for seismically excited torsionally coupled building structures. Floor acceleration and velocity information have been used as feedback to the fuzzy logic controller. A three branch tournament Genetic Algorithm has been used for the multiobjective optimal design of the FLC driven HMD system, where the minimization of the non‐dimensionalized peak displacement, acceleration and rotation of the structure about its vertical axis, have been as the three objective functions. The proposed multiobjective optimal fuzzy logic controller has been verified for an example problem reported in the literature. This HMD system consists of four HMDs arranged in such a way that the system can control the torsional mode of vibration effectively in addition to the flexure modes of vibration. Copyright © 2002 John Wiley & Sons, Ltd.     

磁流变阻尼器对高层建筑风振舒适度的半主动控制分析

高层建筑风振舒适度的控制是结构抗风设计的一项重要内容。本文提出了磁流变阻尼器对高层建筑风振舒适度控制的一种设计方法。由于加速度是舒适度的判别标准，因此，首先通过对依据现行规范计算和用计算机模拟两种方法下得到的加速度进行比较，进而对模拟的脉动风荷载进行合理的修正，并以此作为抗风设计的依据；其次，根据磁流变阻尼器在不同位置时的控制效果，合理地布置控制装置，在此基础上，通过对加速度的有效控制来满足结构舒适度要求；最后，对磁流变阻尼器的参数进行合理的设计，达到优化的目的。     

宿迁市文体馆基础隔震非线性时程分析研究

宿迁市文体馆4500座位，约13000m^2,位于8度抗震设防区，主体结构为钢筋混凝土结构空间框架，钢网壳屋盖。该工程采用基础隔震技术设计，在桩基顶面与上部结构之间设置架空层，用作安置设备管道及隔震层。隔震层由叠层橡胶隔震支座和粘滞阻尼器组成。对主体结构基础隔震采用空间模型非线性时程分析方法进行了详细分析，结果表明：采用基础隔震措施可显著降低结构地震作用，上部结构水平地震作用减震系数可按0．25采用；设置附加粘滞阻尼器能较好地解决降低地震作用和限制隔震层位移之间的矛盾，对提高隔震体系的性能具有重要作用。技术经济比较表明，本工程采用基础隔震措施，具有明显的社会、经济效益。     

Vehicle effects on seismic response of a simple‐span bridge during shake tests

Presence of vehicles on a bridge has been observed many times during past earthquakes. Although in practice, the engineers may or may not include the live load contribution to seismic weight in design, current bridge design codes do not specify a certain guideline. A very limited research has been conducted to address this issue from design point of view. The focus of this research is to experimentally assess the effect of a vehicle on the seismic response of a bridge through a large‐scale model. In this scope, a 12‐meter long bridge, having a one lane deck with concrete slab on steel girders, has been shaken under five different ground motions obtained from recent earthquakes that occurred in Turkey, in its transverse direction, both with and without a vehicle on top of the deck. The measured results have indicated that top slab transverse acceleration and bearing displacements can reduce up to 18.7% in presence of a vehicle during seismic tests, which is an indication of reduction in substructure forces. The main reason for the reduction in seismic response of the bridge in the presence of live load can be ascribed to the increase in damping of the system due to mass damper‐like action induced by the vehicle. This beneficial effect cannot be observed in vertical seismic response. Copyright © 2014 John Wiley & Sons, Ltd.     

某型钢混凝土框架核心筒消能减震结构的弹塑性分析

某工程位于昆明市,主体结构高153.1m,为型钢混凝土框架-剪力墙核心筒体系。建筑总高度超过了《高层建筑混凝土结构技术规程》中规定的B级高度,为提高结构的抗震性能,该工程采用消能减震技术控制结构的地震反应,对消能减震结构进行了设计,确定了消能器附加给结构的阻尼比值。为给结构设计提供可靠的参考依据,采用PERFORM-3D软件,对设有非线性粘滞阻尼器的该结构进行罕遇地震作用下动力弹塑性时程分析,评估该结构的整体性能及其构件的屈服情况,结果表明该消能减震结构基本能达到预期抗震性能目标。     

Full-scale dynamic testing of response-controlled buildings and their components:concepts,methods,and findings

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 results are briefly described,and good performance of the dampers and frame demonstrated. The concepts of the full-scale building tests and various contributions are discussed. The difficulty associated with full-scale dynamic testing is explained.     

Development of steel dampers for bridges to allow large displacement through a vertical free mechanism

Isolation bearings and dampers are often installed between piers and superstructures to reduce the seismic responses of bridges under large earthquakes. This paper presents a novel steel damper for bridges. The damper employs steel plates as energy dissipation components, and adopts a vertical free mechanism to achieve a large deformation capacity. Quasi-static tests using displacement-controlled cyclic loading and numerical analyses using a finite element program called ABAQUS are conducted to investigate the behavior of the damper, and a design methodology is proposed based on the tests and numerical analyses. Major conclusions obtained from this study are as follows:(1) the new dampers have stable hysteresis behavior under large displacements;(2) finite element analyses are able to simulate the behavior of the damper with satisfactory accuracy; and(3) simplified design methodology of the damper is effective.     

Real‐time hybrid testing of a smart base isolation system

Real‐time hybrid testing is a very effective technique for evaluating the dynamic responses of rate‐dependent structural systems subjected to earthquake excitation. A smart base isolation system has been proposed by others using conventional low‐damping isolators and controllable damping devices such as magnetorheological (MR) dampers to achieve specified control target performance. In this paper, real‐time hybrid tests of a smart base isolation system are conducted. The simulation is for a base‐isolated two‐degrees‐of‐freedom building model where the superstructure and the low‐damping base isolator are numerically simulated, and the MR damper is physically tested. The target displacement obtained from the step‐by‐step integration of the numerical substructure is imposed on the MR damper, which is driven by three different control algorithms in real‐time. To compensate the actuator delay and improve the accuracy of the test, an adaptive phase‐lead compensator is implemented. The accuracy of each test is investigated by using the root mean square error and the tracking indicator. Experimental results demonstrate that the hybrid testing procedure using the proposed actuator compensation techniques is effective for investigating the control performance of the MR damper in a smart base isolation system. Copyright © 2013 John Wiley & Sons, Ltd.