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Field measurements are critical to further understand the structural behavior of super-tall buildings under strong wind actions. This paper presents field measurements that reflect the wind characteristics and wind effects on Leatop Plaza under Typhoon Vicente. Wind field characteristics, including the turbulence intensity, gust factor, and power spectral density of wind speed in an urban area, were obtained on the basis of a statistical analysis of measured wind data. Subsequently, measured wind-induced accelerations were used to evaluate the dynamic characteristics of the building and the effects of wind on it. On the basis of the first several modes, the modal properties, i.e., the natural frequency and damping ratio, were identified via the fast Bayesian fast Fourier transform method and compared with those identified using the stochastic subspace method. The discrepancy between the identified results and finite element model predictions is presented and discussed. Finally, the variation in the modal parameters with respect to time and the vibration amplitude was analyzed while considering the associated posterior uncertainty. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer composites can be externally bonded to reinforced concrete members which provide an effective seismic retrofit strategy for reinforced concrete structures. For seismic retrofit of a complex building structure, due to the large number of structural members, an optimum design which ensures the use of the minimum amount of fiber-reinforced polymer to achieve a given level of seismic performance is highly desirable for economic reasons. In addition, such an optimum design approach is best built on a probabilistic basis so that various sources of uncertainties in the design process can be appropriately accounted for. This work therefore studies an efficient reliability-based optimization approach for the seismic retrofit design of reinforced concrete structures using fiber-reinforced polymer composites. The structural performance is assessed at the system level using nonlinear pushover analyses. In the proposed approach, the inelastic interstory drift ratios are modeled as indeterministic variables to consider the uncertainties of earthquake loading. By contrast, the thickness of the fiber-reinforced polymer jacket is considered as a deterministic design variable. The reliability-based design approach is formulated by minimizing fiber-reinforced polymer cost subject to prescribed structural reliability constraints. Using the results of nonlinear static pushover analyses and reliability analyses, the reliability index constraints are explicitly formulated with respect to the deterministic design variables based on the virtual work principle as well as Taylor series expansion. A numerical optimality criteria method is derived and programmed to solve this reliability-based nonlinear retrofit design optimization problem. A design example is included to illustrate the application of the new optimization approach. [ABSTRACT FROM AUTHOR]

The vector decomposition method was firstly adopted in this paper to process the measured wind speed data atop the super high-rise building Guangzhou West Tower. Three limitations of this widely used statistic a analysis method in wind engineering were discussed. In order to solve these limitations and obtain more accurate fluctuating wind speed time history, the non-stationary characteristics of wind was taken into account in this study. Therefore a revised stationary and non-stationary (mainly induced from the EMD method) wind speed model were established respectively for the two orthogonal directions of the fluctuating wind speed obtained from the propeller anemometer. Then the four major indexes of wind characteristic for measured wind speed, i. e. the turbulence intensity, the gust factor, the probability density distribution, and the power spectral density of fluctuating wind speed, were discussed comprehensively by comparing the analyzed results based on the specifications of the two above mentioned wind speed model. The comprehensive compared results showed that non-stationary wind speed model, which was obtained from the EMD method, could describe the true state of wind characteristic of on-site measured wind speed data more accurately. [ABSTRACT FROM AUTHOR]