The objective of this paper is to present the idea of control of the dual-mode buffeting response in suspension bridges under service conditions using two tuned mass dampers TMDs. The bridge is assumed to vibrate in two vertical modes, which are to be controlled using two TMDs. The TMDs' properties are determined by minimizing the maximum buffeting response of the bridge. By neglecting modal coupling terms, some approximate formulas are derived. A numerical example is used to understand the requirements for the TMDs. The results show that, as compared to using only one TMD, the dual TMDs offer a more pronounced response reduction. The results also reveal some disadvantages of using the TMD system for buffeting vibration control. The major one is that the efficiency of the TMD system declines and the strokes increase significantly as the wind speed increases.

The sinusoidal reference strategy (SRS) is a new strategy developed by the present authors for adaptive feedforward vibration control. The recursive-least-squares algorithm is used and a higher frequency sinusoidal signal is adopted as the reference signal. Some shortcomings of the conventional adaptive feedforward control are overcome. Numerical simulations and experimental studies have been carried out. The results show that this strategy can reduce vibration remarkably, and can adapt in real time to dynamic uncertainties and modeling errors. In this paper, the principle of SRS-based adaptive feedforward control is briefly introduced first, then simulation studies are conducted on reducing wind-induced response of the benchmark wind-excited building. The results are also compared to that obtained from linear quadratic Gaussian control.

A new control approach named Sinusoidal Reference Strategy is developed for adaptive feedforward structural control. In this approach, the recursive-least-squares algorithm is used and a higher frequency sinusoidal signal is utilized as the reference signal. The present approach is able to overcome some of the shortcomings of the conventional adaptive feedforward control. Numerical simulations are then conducted on reducing wind-induced vibrations of the JIN MAO Building in Shanghai, China, with a height of 420 m. A multiple-degree-of-freedom (m.d.o.f.) aeroelastic model of a general super-tall building and an active mass damper (AMD) actuator are designed and manufactured. Wind tunnel tests are carried out to investigate further the control efficiency and robustness of the present approach. Both the simulation and experimental results show that the approach can reduce vibration of super-tall buildings remarkably, and can adapt to dynamic uncertainties and modelling errors of the buildings.

A study on buffeting control of the Yangpu Bridge using a multiple tuned mass damper (MTMD) system is performed in this paper. The MTMD system consists of a set of TMDs which are attached to the center region of the bridge's main span and are symmetrical about the center of the main span as well as about the central line along the bridge span. It is found that the control efficiency of the MTMD system is sensitive to its frequency characteristics, namely, the central frequency ratio and the frequency bandwidth ratio. On the other hand, the damping ratio of the TMDs has less significant effects on the control efficiency. A total of seven MTMD systems with different mass ratios are designed. Each one of these seven MTMD systems can be used for the buffeting control of the Yangpu Bridge, depending on the required control efficiency and the available budget.

The method for identification of flutter derivatives of bridge decks developed by the authors is first briefly described in this paper. To investigate the effects of dynamic parameters of a bridge deck model on the flutter derivatives a test of the sectional Jiangyin Bridge deck's models with different dynamic parameters was carried out in a boundary layer wind tunnel using the present identification method. In both smooth and simulated turbulent flow conditions, a plate model and the sectional deck model of the Jiangyin Bridge were tested to further survey the effects of turbulence on flutter derivatives. The identified results tend to indicate that the effects of parameters of the model and turbulence on the flutter derivatives are negligible.

Traditionally, wind analysis procedures based on the "gust loading factor" approach and experimental techniques involving the high frequency base balance and the "stick-type" aeroelastic model test have assumed ideal structural mode shapes, i.e., linear lateral modes and uniform torsional modes. The influence of nonideal mode shapes manifests itself through modifications in the generalized wind load, the structural displacement, the equivalent static wind load (ESWL), and the attendant influence function. This has led to the introduction of several correction procedures, each focusing on an individual feature of the overall response analysis framework. This paper presents a systematic development of correction procedures in terms of correction factors (CFs) to account for nonideal mode shapes in the formulation of eneralized load, analysis of structural response, and the derivation of the ESWL. A parameter study is conducted to examine the significance of CFs in estimating various load effects. It is observed that the influence of a nonideal mode shape is actually negligible for the displacement response and the base bending moment, but not so for other load effects, e.g., the base shear and the generalized wind load. Although the existing procedures are effective in correcting the intended response component, they should not be used indiscriminately for other load effects. This paper also presents a correction procedure for the influence of mode shapes on the ESWLs, a loading format that is very attractive for implementation in codes and standards and design practice as well as for the correct interpretation of wind tunnel measurements.

In this paper increasing the critical flutter wind speed of long-span bridges by using tuned mass dampers (TMDs) is theoretically and experimentally studied. Equations governing the motions of a bridge with TMDs are established. The Routh-Hurwitz stability criterion is used to study the aerodynamic instability of the bridge based on the characteristic equation of the system of the bridge and TMDs. A sectional model wind-tunnel test on the Tiger Gate Bridge, a suspension bridge with a steel box deck and a center span of 888 m, is carried out to confirm the numerical results. Some new findings from the test and the calculation are presented.

An identification method has been developed to extract all the flutter derivatives defined by R.H. Scanlan. In the present work, the signals of the coupled vertical torsional free vibration of the spring-suspended section model are used. The fiutter derivatives of a thin plate obtained using the present method are compared with the corresponding Theodorsen theoretical values. The present method is then used in the identification of flutter derivatives of the Jiangyin suspension Bridge over Yangtze River. The flutter critical wind speed of this bridge obtained from the full bridge aeroelastic model test in a wind tunnel shows good agreement with the estimated result from Scanlan's flutter analysis method with the flutter derivatives using the present method.

Flutter-based selection for the Jiangyin Bridge, a suspension bridge with a main span of 1385m, was made through a sectional model wind tunnel test. The concept of

As the main span of modern cable-stayed bridges becomes longer and longer, the buffetinginduced fatigue damage problem of steel girders located in strong wind regions may have to be taken into consideration in the design of the bridge. This paper presents a method in the mixed frequency-time domain for estimating the fatigue life of steel girders of the Yangpu cable-stayed Bridge due to buffeting. In the suggested method, the joint probability density function of wind speed and wind direction at the deck level of the bridge is