20-story Benchmark Building Research Articles

High-performance isolation systems with rate-independent linear damping for seismic protection of high-rise buildings

There is currently growing concern within the earthquake engineering community regarding the potential for base-isolated structures to experience significant responses during extreme earthquakes. This concern is primarily driven by the observation that induced ground motions can contain influential long-period components, which may exacerbate the structural response. Supplementing damping using conventional damping devices contributed to a significant reduction in the responses whereas perhaps compromises the effects of base isolation itself when subjected to more frequently occurring short-period ground motions, particularly for base-isolated high-rise building structure. The present study employs rate-independent linear damping (RILD) to control the seismic response of high-rise building structures subjected to both short- and long-period ground motions. RILD is a damping mechanism that exerts a control force that is independent of the vibration frequency under harmonic deformation. This method is implemented in conjunction with isolators to achieve the desired control objectives. For passive realization of RILD, both the Maxwell-negative-stiffness (MNS) and modified tuned Maxwell–Wiechert (MTMW) models were considered. A regression technique is presented in this study to optimally design the properties of the MTMW model, and a recursive formulation is developed to conduct structural response history analyses efficiently. The proposed method for seismic protection of high-rise structures was demonstrated using a 20-story benchmark building structure as the analytical model. This approach serves to illustrate the advantages of the proposed method in a practical context. Both short- and long-period ground motions are used for examining the performance of rate-independent damping models incorporated into base-isolated high-rise structures. The findings suggest that the combined isolation systems, in conjunction with rate-independent linear damping (RILD), offer significantly enhanced protection against conventional short-period ground motions, without sacrificing performance during long-period ground motions. Compared to commonly utilized isolation systems, this approach demonstrates superior performance in safeguarding high-rise structures.

Multi-modal seismic control design for multi-storey buildings using cross-layer installed cable-bracing inerter systems: Part 1 theoretical treatment

Many attempts have been made to improve the performance of buildings subjected to ground motions with a novel mechanic element, known as an inerter, thereby giving buildings more stability. Recently, a characteristic of the inerter system on controlling the target mode, called the target mode control effect, has been discovered. Considering the prospects of target mode control effect on controlling those buildings affected by multi-modal responses, in this study, cross-layer installed cable-bracing inerter systems (CICBISs) will be used for the multi-modal seismic control. For releasing the end torsion constraints demand of the ball-screw inerter and simplifying the CICBIS's realization, a self-balanced inerter is proposed. A multi-modal seismic control design strategy is proposed to determine the optimal parameters of CICBISs. The equivalent mass with a physical meaning of the multi-storey building with a CICBIS is proposed to quantify the control efficiency of the CICBIS's placement and determine the installation placement of CICBISs directly. A 20-story benchmark building is used to validate the design strategy. The results show that the CICBISs tuned to multi-modes through applying the proposed design strategy can simultaneously focus on controlling multiple target modes. Moreover, it is proved that under the same constraint on each device's control force, the designed CICBISs obtain a higher efficiency on suppressing seismic responses than those CICBISs for single-modal seismic control we proposed in the past and cross-three-layer installed tuned viscous mass dampers. Further sections of the study, including device tests on a self-balanced inerter's prototype and shake table tests on corresponding CIBCIS, will be offered in the following companion paper: Part 2 Experimental treatment.

Real-time hybrid testing for active mass driver system based on an improved control strategy against control-structure-interaction effects

General real-time hybrid testing (RTHT) for active mass driver (AMD) system requires shake table to achieve boundary conditions between the numerical and experimental substructures, which may be unavailable in some situations. Simplified RTHT is free of shake table, but it cannot consider control-structure-interaction (CSI) effects, and may result in an inaccurate performance evaluation of AMD system due to a significant influence of CSI on control performance. In this study, to eliminate the CSI effects, an improved control strategy is proposed, by incorporating the acceleration of control floor into the AMD controller and transforming all the control commands and feedbacks from the geocentric coordinate system to the relative coordinate system. Based on this strategy, the implementations of general and simplified RTHTs for AMD system are described. Experimental investigations are conducted on a two-story structure equipped with an AMD. It is confirmed that the general RTHT can be used to evaluate the actual performances of different control strategies. The CSI effects are essentially eliminated by the improved control strategy, but adversely affect the performance of traditional control strategy. In addition, the simplified RTHT is inappropriate for the performance evaluation of the traditional control strategy, but is available to that of the improved control strategy. Finally, an AMD control scheme is presented for a seismically excited 20-story benchmark building, and is evaluated through the simplified RTHT. Experimental results demonstrate the effectiveness of the proposed AMD control scheme. The maximum roof displacement and acceleration decrease from 0.175 m and 3.059 m/s2 to 0.116 m and 1.356 m/s2, respectively, when subjected to the El Centro earthquake.

Strain amplitude effects on the seismic performance of dampers utilizing shape memory alloy wires

Superelastic shape memory alloys (SMAs) are unique smart materials with a considerable energy dissipation potential for the vibration control of structures. The energy dissipation arises from the hysteretic phase transformation. Random vibration patterns, such as by earthquakes and wind, include not only changing strain rates but also different strain amplitudes. Previous studies revealed that the reverse phase transformation behavior of SMAs depend apart from the strain rate also on the strain amplitude. This study confirms these findings by experiments and proposes a modeling approach for an accurate representation of this effect. Both tensile cyclic and seismic responses of Nitinol wires are studied for this purpose. The modeling approach is validated by the experimental results. Finally, the proposed model is applied numerically to a seismically excited 20-story benchmark building incorporating multiple SMAs. An intermediate time stepping approach is employed, which improves both the computational efficiency and the accuracy of the simulation process.

Investigations on the Performance of a Novel Semi-active Tuned Liquid Column Damper

A semi-active tuned liquid column damper (S-TLCD) is proposed, which can tune both the natural frequency and the damping ratio autonomously. The S-TLCD reaches a robust high-level damping performance by adapting its parameters to the changing loading and structural conditions. Degradation effects, soil-structure interaction and environmental variations can cause such changes. This paper summarizes the results of the numerical and experimental investigations on the performance of the damper. For the numerical analyses, a seismically excited 20-story benchmark building is used. The calculation results are compared with a passive tuned mass damper (TMD). Due to its adaptation capacity, the S-TLCD shows a higher performance regardless of the fluctuations in the natural frequency of the building. On the experimental part of the study, the frequency change capacity of the S-TLCD is also documented by using shake table tests and comparing the results with the analytical solutions.

A semi-active H∞ control strategy with application to the vibration suppression of nonlinear high-rise building under earthquake excitations.

Different from previous researches which mostly focused on linear response control of seismically excited high-rise buildings, this study aims to control nonlinear seismic response of high-rise buildings. To this end, a semi-active control strategy, in which H∞ control algorithm is used and magneto-rheological dampers are employed for an actuator, is presented to suppress the nonlinear vibration. In this strategy, a modified Kalman–Bucy observer which is suitable for the proposed semi-active strategy is developed to obtain the state vector from the measured semi-active control force and acceleration feedback, taking into account of the effects of nonlinearity, disturbance and uncertainty of controlled system parameters by the observed nonlinear accelerations. Then, the proposed semi-active H∞ control strategy is applied to the ASCE 20-story benchmark building when subjected to earthquake excitation and compared with the other control approaches by some control criteria. It is indicated that the proposed semi-active H∞ control strategy provides much better control performances by comparison with the semi-active MPC and Clipped-LQG control approaches, and can reduce nonlinear seismic response and minimize the damage in the buildings. Besides, it enhances the reliability of the control performance when compared with the active control strategy. Thus, the proposed semi-active H∞ control strategy is suitable for suppressing the nonlinear vibration of high-rise buildings.

Optimal Control of Magnetorheological Fluid Dampers for Seismic Isolation of Structures

This paper presents the modeling and control of a magnetorheological (MR) damper, installed in Chevron configuration, at the base of a 20-story benchmark building. The building structural model is created using the commercial software package ETABS. The MR damper model is derived from Bouc-Wen hysteresis model which provides the critical nonlinear dynamics that best represents the MR damper under a wide range of operating conditions. System identification is used to derive a low-order nonlinear model that best mimics the nonlinear dynamics of the actual MR damper. Dynamic behavior of this low-order model is tested and validated over a range of inputs. The damper model has proven its validity to a high degree of accuracy against the nonlinear model. A Kalman filter is designed to best estimate the state of the structure-damper system for feedback implementation purposes. Using the estimated states, an LQG-based compensator is designed to control the MR damper under earthquake loads. To demonstrate the effectiveness of this control strategy, four historical earthquakes are applied to the structure. Controlled and uncontrolled floor accelerations and displacements at key locations are compared. Results of the optimally controlled model demonstrate superior performance in comparison to the uncontrolled model.

Application of Centralized and Decentralized Control to Building Structure: Analytical Study

This paper presents both the centralized and decentralized control strategies by using semiactive control devices (magnetorheological dampers) for building structural control under seismic excitations. The control algorithms used in this study only focus on the linear quadratic Gaussian control theory with acceleration measurements as feedback signals. In the centralized control, the control force is generated directly from the measurement in each degree of freedom, while in the decentralized control, only measurement from local subsystems is used to calculate the control force with respect to the locations of control devices and measurements. Four groups of centralized/decentralized control algorithms are studied: fully centralized control, fully decentralized control, half-centralized control, and partially decentralized control. The ASCE 20-story benchmark building is selected as an example to evaluate the control performance among different control strategies.

Semi-active model predictive control for 3rd generation benchmark problem using smart dampers

A semi-active strategy for model predictive control (MPC), in which magneto-rheological dampers are used as an actuator, is presented for use in reducing the nonlinear seismic response of high-rise buildings. A multi-step predictive model is developed to estimate the seismic performance of high-rise buildings, taking into account of the effects of nonlinearity, time-variability, model mismatching, and disturbances and uncertainty of controlled system parameters by the predicted error feedback in the multi-step predictive model. Based on the predictive model, a Kalman-Bucy observer suitable for semi-active strategy is proposed to estimate the state vector from the acceleration and semi-active control force feedback. The main advantage of the proposed strategy is its inherent stability, simplicity, on-line real-time operation, and the ability to handle nonlinearity, uncertainty, and time-variability properties of structures. Numerical simulation of the nonlinear seismic responses of a controlled 20-story benchmark building is carried out, and the simulation results are compared to those of other control systems. The results show that the developed semi-active strategy can efficiently reduce the nonlinear seismic response of high-rise buildings.

Application of a Genetic Algorithm for Optimal Damper Distribution within the Nonlinear Seismic Benchmark Building

This paper presents a systematic method for identifying the optimal damper distribution to control the seismic response of a 20-story benchmark building. A genetic algorithm with integer representation was used to determine the damper locations. Both H2- and H∞-norms of the linear system transfer function were utilized as the objective functions. Moreover, frequency weighting was incorporated into the objective functions so that the genetic algorithm emphasized minimization of the response in the second mode of vibration instead of the dominant first mode. The results from numerical simulations of the nonlinear benchmark building show that, depending on the objective function used, the optimal damper locations can vary significantly. However, most of dampers tend to be concentrated in the lowermost and uppermost stories. In general, the damper configurations evaluated herein performed well in terms of reducing the seismic response of the benchmark building in comparison to the uncontrolled building.

Semiactive Control of the 20-Story Benchmark Building with Piezoelectric Friction Dampers

A new control algorithm is proposed in this paper to control the responses of a seismically excited, nonlinear 20-story building with piezoelectric friction dampers. The passive friction damping mechanism is used for low-amplitude vibration while the active counterpart takes over for high-amplitude vibration. Both the stick and sliding phases of dampers are taken into account. To effectively mitigate the peak story drift and floor acceleration of the 20-story building, multiple dampers are placed on the 20-story building based on a sequential procedure developed for optimal performance of the dampers. Extensive simulations indicate that the proposed semiactive dampers can effectively reduce the seismic responses of the uncontrolled building with substantially less external power than its associated active dampers, for instance, 67% less under the 1940 El Centro earthquake when the passive friction force is equal to 10% of the damper capacity.

Control Effect for 20-Story Benchmark Building Using Passive or Semiactive Device

In this paper, we study the control effect for a 20-story benchmark building and apply passive and semiactive control devices to the building. First, we take viscous damping walls as a passive control device which consists of two outer plates and one inner plate, facing each other with a small gap filled with viscous fluid. The damping force is related to the interstory velocity, temperature, and the shearing area. Next, we take a variable oil damper as a semiactive control device which can produce the control forces by little electrical power. We propose a damper model in which the damping coefficient changes according to the response of the damper and control forces calculated by the controller based on a linear quadratic Gaussian control theory. It is demonstrated from the results of some simulations that both passive device and semiactive device can effectively reduce the response of the structure in various earthquake motions.