Structural systems often show nonlinear behavior under severe excitations generated by natural hazards. In that condition, the restoring force becomes highly nonlinear showing significant hysteresis. The hereditary nature of this nonlinear restoring force indicates that the force cannot be described as a function of the instantaneous displacement and velocity. Accordingly, many hysteretic restoring force models were developed to include the time dependent nature using a set of differential equations. This survey contains a review of the past, recent developments and implementations of the Bouc-Wen model which is used extensively in modeling the hysteresis phenomenon in the dynamically excited nonlinear structures.

The Hysteresis Bouc-Wen Model, a Survey

https://nottingham-repository.worktribe.com/preview/949995/ChenEtAl18b_authorVersion.pdf

A machine learning method to estimate PM2.5 concentrations across China with remote sensing, meteorological and land use information.

This paper presents some of the oral discussion by the author and others at the 2005 Annual Meeting of the Los Angeles Tall Buildings Structural Design Council. It also includes additional opinions added by the author after the annual meeting. These opinions address the development of a new building code for tall buildings and where the non-structural engineering decision makers can and must make contributions. It also addresses the very important topic of quality control. Copyright © 2005 John Wiley & Sons, Ltd.

The structural design of tall and special buildings

Magnetorheological fluid technology has gained significant development during the past decades. The application of magnetorheological fluids has grown rapidly in civil engineering, safety engineering, transportation, and life science with the development of magnetorheological fluid–based devices, especially magnetorheological fluid dampers. The magnetorheological fluid dampers could offer an outstanding capability in semiactive vibration control due to excellent dynamical features such as fast response, environmentally robust characteristics, large force capacity, low power consumption, and simple interfaces between electronic input and mechanical output. To address the fast growing demand on magnetorheological fluid damping technology in extensive engineering practices, the state-of-the-art development is presented in this article, which provides a comprehensive review on the structure design and its analysis of magnetorheological fluid dampers (or systems). This can be regarded as a useful complement to...

Magnetorheological fluid dampers: A review on structure design and analysis

Non-linear hysteresis is a complicated phenomenon associated with magnetorheological (MR) fluid dampers. A new model for MR dampers is proposed in this paper. For this, computationally-tractable algebraic expressions are suggested here in contrast to the commonly-used Bouc–Wen model, which involves internal dynamics represented by a non-linear differential equation. In addition, the model parameters can be explicitly related to the hysteretic phenomenon. To identify the model parameters, a particle swarm optimization (PSO) algorithm is employed using experimental force–velocity data obtained from various operating conditions. In our algorithm, it is possible to relax the need for a priori knowledge on the parameters and to reduce the algorithmic complexity. Here, the PSO algorithm is enhanced by introducing a termination criterion, based on the statistical hypothesis testing to guarantee a user-specified confidence level in stopping the algorithm. Parameter identification results are included to demonstrate the accuracy of the model and the effectiveness of the identification process.

A novel hysteretic model for magnetorheological fluid dampers and parameter identification using particle swarm optimization

Estimation of long-term population exposure to PM2.5 for dense urban areas using 1-km MODIS data

In an attempt to validate the effectiveness of a magnetorheological (MR) damper in controlling the wind-induced response of a building model in a wind tunnel, it is necessary to have a damper which produces a range of small forces so that it can be used to control the light-weight building model. In this study, a small-scale rotary type of MR damper is designed, manufactured, and tested. The damper uses shear-mode behavior of the MR fluids and is designed based on the simple Bingham viscoplastic model. A prototype damper that can produce forces in the order of a few newtons is made and tested in the laboratory. It is found that the Bouc-Wen model, which has been used to emulate linear valve-mode MR dampers, can also portray the hysteretic behavior of the shear-mode rotary damper. A simplified yet relatively accurate inverse dynamic model that can directly relate the damper force to the input voltage is proposed. Experiments demonstrate that a MR damper using this inverse model can closely reproduce prescribed forces. This inverse model provides an alternative means of commanding the MR damper for control applications.

Shear-Mode Rotary Magnetorheological Damper for Small-Scale Structural Control Experiments

Serious particulate matter (PM) pollution problems in many polluted regions of China have been frequently reported in recent years. Long-term exposure to ambient PM pollution is significantly associated with adverse health effects. Characterizing the long-term trends and variation in PM pollution is a basic requirement for evaluating long-term exposure and for guiding future policies to reduce the effects of air pollution on health. However, long-term, ground-based PM measurements are only available at a few fixed stations. In this study, an algorithm is developed and validated to estimate PM concentrations based on the satellite atmospheric optical depth with 1 km spatial resolution. The long-term trends of PM10 concentrations in the entire Pearl River Delta (PRD) region and different cities are quantified and discussed. From 2001 to 2013, the PM10 pollution of the entire PRD region was dominated by a decreasing trend of -0.15 ± 0.23 μg/m(3)·yr. This decreasing PM10 trend was apparent over 75% of the PRD area, with the most significant decreases observed in the center of the region. However, the remaining 25%, mostly located in the outskirts of the region, showed an increasing PM10 trend. This overall decreasing trend indicates the effectiveness of the control measures applied in the past decade for the primary pollutants.

Assessing Long-Term Trend of Particulate Matter Pollution in the Pearl River Delta Region Using Satellite Remote Sensing

Dynamic Mode Decomposition on pressure flow field analysis: Flow field reconstruction, accuracy, and practical significance

To evaluate different energy dissipation systems used to control wind-induced vibrations of a 456 m super-tall building in fluctuating wind excitations, the finite element (FE) method was employed to simulate the dynamic responses of the building. A series of wind tunnel pressure tests were conducted on a 1:450 scale model to determine the wind forces acting on the super-tall building. A FE model was also constructed and mass, damping and stiffness matrices were subsequently formulated as an evaluation model for numerical analysis. The evaluation model was further simplified to a state reduced-order system using the state order reduction method. Three different vibration control schemes, namely a tuned mass damper (TMD) system, a system containing only nonlinear viscous dampers and a hybrid control system combining TMD and viscous dampers, were examined through simulations with respect to their effectiveness in reducing the accelerations at the top of the building. Furthermore, a cost evaluation was condu...

Tim K.T. Tse

Papers

Estimation of long-term population exposure to PM2.5 for dense urban areas using 1-km MODIS data

Shear-Mode Rotary Magnetorheological Damper for Small-Scale Structural Control Experiments

Assessing Long-Term Trend of Particulate Matter Pollution in the Pearl River Delta Region Using Satellite Remote Sensing

Dynamic Mode Decomposition on pressure flow field analysis: Flow field reconstruction, accuracy, and practical significance

Structural performance and cost analysis of wind-induced vibration control schemes for a real super-tall building