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This paper discusses the uncertainty when estimating extreme values of wind-induced lateral accelerations in a high-rise building based on wind-tunnel measurements. The acceleration signals for an aeroelastic scale model under ten different velocities and three different wind angles were processed to evaluate the extreme acceleration values. The empirical cumulative distribution function (CDF) and probability density function (PDF) trends of the peaks were estimated and compared with the analytical models, which showed satisfactory fits. An effort was made for the best fit for the empirical CDF through the numerical expansion of the peak set using Polynomial Chaos Expansion (PCE). It was confirmed that in this case, the lack of a reliable fit was not due to the number of peaks. In addition, analytical models of the Gaussian and non-Gaussian processes were applied to estimate the extreme values using the entire process and the sub-processes, and this paper compares and discusses the results. Finally, the variability of the extreme acceleration values estimated using a total of ten different methods is discussed.

To investigate the coupling effects of wave–wind, wave–current, and wave–current–wind on a pile foundation of a marine structure, harbor basin tests on loads induced by single and combined action of wave, current, and wind were conducted. The time histories, power spectrums, and characteristic values of drag forces in the test conditions were compared. Then, the coupling coefficients were calculated based on the characteristic values to quantitively evaluate the coupling effects. The influence of natural vibration of the pile on the characteristic values and coupling effects were studied by comparing the test loads between rigid and elastic models. The results show that the shapes of power spectrums of drag forces and their peak frequencies in the wave-involved conditions are similar to the spectrum of incident wave, which means that the steady current and uniform wind cannot change the frequency distribution of incident random wave. Although the drag forces of rigid and elastic model under wave–wind, wave–current, and wave–current–wind are not the linear superposition of corresponding single field, the coupling effects among them are quite weak as the coupling coefficients are small. It is speculated that the weak wave–wind coupling effect may be because, firstly, the interaction of wave and wind is limited to the zone near the water surface, which is far less than the height of the model; secondly, the wave-induced load is dominant compared to wind and current. The loads in test conditions of elastic model are similar to the rigid model; for that, the model’s natural frequency is far away from the peak spectral frequency of incident wave, having little influence on the drag force.

In this paper, a series of full-scale wind tunnel tests are conducted to study the vortex-induced vibration (VIV) of the steel tubes connected with C-shaped bolted joints. The dynamic prope...

This paper examines the mean wind profiles of tropical cyclones (TCs) toward 1,000-m height with a low-level jet (LLJ) feature over the Southeast China Sea based on the newly released fifth...

This paper investigated the evolution of tropical cyclone (TC) wind threat from the past into the future and discussed its implications for the building code specifications for two vulnerab...

Synchronous multi-pressure measurements were carried out with relatively long time duration for a double-layer reticulated shell roof model in the atmospheric boundary layer wind tunnel. Since the long roof is open at two ends for the storage of coal piles, three different testing cases were considered as the empty roof without coal piles (Case A), half coal piles inside (Case B) and full coal piles inside (Case C). Based on the wind tunnel test results, non-Gaussian time-dependent statistics of net wind pressure on the shell roof were quantified in terms of skewness and kurtosis. It was found that the direct statistical estimation of high-order moments and peak factors is quite sensitive to the duration of wind pressure time-history data. The maximum value of COVs (Coefficients of variations) of high-order moments is up to 1.05 for several measured pressure processes. The Mixture distribution models are proposed for better modeling the distribution of a parent pressure process. With the aid of mixture parent distribution models, the existing translated-peak-process (TPP) method has been revised and improved in the estimation of non-Gaussian peak factors. Finally, non-Gaussian peak factors of wind pressure, particularly for those observed hardening pressure process, were calculated by employing various state-of-the-art methods and compared to the direct statistical analysis of the measured long-duration wind pressure data. The estimated non-Gaussian peak factors for a hardening pressure process at the leading edge of the roof were varying from 3.6229, 3.3693 to 3.3416 corresponding to three different cases of A, B and C.

SUMMARY This paper presents a practical method for evaluating lateral-torsional coupling in the elastic earthquake response of asymmetric multistory buildings. A transformation technique is first developed to shift the floor centers of mass of an asymmetric building to new reference positions where the sum of the squares of all floor rotations of the building due to lateral inertia loads is a minimum. By setting the locus of the floor centers of mass of the building at the new reference positions, a representative eccentricity and an effectively uncoupled system for the building can be established on the basis which an equivalent eccentric single mass system can be developed. The additional lateral translations caused by seismic torsional effects in the building can be analytically determined and expressed in terms of the representative building eccentricity and the uncoupled periods evaluated using the effectively uncoupled system. The effectiveness and practicality of the proposed method are illustrated with two 30-story practical buildings. Copyright © 2013 John Wiley & Sons, Ltd.

This paper investigates wind pressure characteristics on a corridor double-skin facade (DSF) of a tall rectangular building through experimental and numerical modeling. Firstly, wind-tunnel experiments have been carried out to study the wind pressures acting on three surfaces of the corridor DSF of the building: the outside and inside surfaces of the external skin and the outside surface of the internal skin. The characteristics of the wind pressure distribution on the DSF are investigated for different DSF layouts, air corridor width and incident wind angles. The mean and standard deviation of the pressure coefficients are presented for twelve wind angles over 360°. The experimental data show complex wind pressure distributions inside and outside the air cavity. Then, the zonal approach is applied to model the inner-gap pressures on the DSF. The results from the zonal modeling compare relatively well with the wind-tunnel measurements. Thus, the zonal approach is an effective tool for evaluating the performance of DSF on tall buildings and may be an efficient alternative to the traditional wind-tunnel test and computational fluid dynamic (CFD) method.

Long-span transmission tower and conductor line systems become important infrastructures in modern societies. The analysis of wind-induced dynamic responses of transmission towers is an essential task in the design of spatial lattice tower structures. Wind effects on the world's tallest transmission tower are presented in this paper. The tower with a total height of 370 metres, part of the Zhoushan long-span transmission project, enables high voltage conductor lines to span as long as 2750 metres over the typhoon-prone sea strait. A multi-DOF aeroelastic model test with and without conductor lines was carried out to investigate the dynamic performances of Zhoushan tower during typhoon events. Using the response measurement results in the wind tunnel, the inertial force based gust loading factors (GLFs) are applied to represent dynamic wind load effects on the tower for structural design purposes. Time domain computational simulation approach is also employed to predict dynamic responses of the transmissio...

SUMMARY This paper focuses on the development of peak factor formulas of non-Gaussian wind pressure processes after reviewing the current estimation methods of non-Gaussian peak factors. A skewness-dependent peak factor is proposed by accounting for the contribution of skewness and kurtosis parameters in some existing Hermite moment-based formulas. The possible correction on the upcrossing rate used in the translation process approach is also investigated. Wind tunnel pressure data on a practical 43-story building with unusual shape is used to validate the accuracy of the skewness-dependent peak factor by investigating various statistical properties of wind-induced fluctuating pressure field on the complex-shaped tall building example. Copyright © 2012 John Wiley & Sons, Ltd.

Equivalent static wind loads (ESWLs) play an important role in the wind-resistant design of tall buildings. Traditionally, ESWLs of a tall building are derived based on the equivalence of the top deflection or the base force along the principal direction, which is easy to identify for a regular tall building. For flexible tall buildings with simple or complex shapes, wind-induced dynamic responses are three-dimensional, which often complicates the application of the ESWLs. Based on the time-domain dynamic analysis method, a new scheme is developed in this paper to model multiobjective equivalent static wind loads (M-ESWLs) on complex tall buildings. The possible non-Gaussian properties of wind-induced response processes have been taken into account in M-ESWLs by using non-Gaussian peak factors. Furthermore, a joint action reduction factor is carefully defined to reflect the partial correlations among multiple component responses. Finally, the new scheme is applied to a practical 43-story tall buil...

This paper presents an integrated wind-induced dynamic analysis and computer-based design optimization technique for minimizing the structural cost of general tall buildings subject to static and dynamic serviceability design criteria. Once the wind-induced dynamic response of a tall building structure is accurately determined and the optimal serviceability design problem is explicitly formulated, a rigorously derived Optimality Criteria (OC) method is to be developed to achieve the optimal distribution of element stiffness of the structural system satisfying the wind-induced drift and acceleration design constraints. The effectiveness and practicality of the optimal design technique are illustrated by a full-scale 60-story building with complex 3D mode shapes. Both peak resultant acceleration criteria and frequency dependent modal acceleration criteria are considered and their influences on the optimization results are highlighted. Results have shown that the use of various acceleration criteria has different implications in the habitability evaluations and subsequently different optimal design solutions. The computer based optimization technique provides a powerful tool for the lateral drift and occupant comfort design of tall building structures.

Structural optimization and vibration control have long been recognized as effective approaches to obtain the optimal structural design and to mitigate excessive responses of tall building structures. However, the combined effects of both techniques in the structural design of wind-sensitive tall buildings with excessive responses have not been revealed. Therefore, this paper develops an integrated design technique making use of both the advantages of structural optimization and vibration control with an empirical cost model of the control devices. While the structural optimization is based on a very efficient optimality criteria (OC) method, a smart tuned mass damper (STMD) is used for the structural control purposes. Utilizing data obtained from synchronous pressure measurements in the wind tunnel, a 60-story building of mixed steel and concrete construction with three-dimensional (3D) mode shapes was employed as an illustrative example to demonstrate the effectiveness of the proposed optimal performance-based design framework integrating with structural vibration control.

The three-dimensional mode shapes found in modern tall buildings complicate the use of the high-frequency base balance (HFBB) technique in wind tunnel testing for predicting their wind-induced loads and effects. The linearized-mode-shape (LMS) method was recently proposed to address some of the complications in the calculation of the generalized wind forces, which serve as the input to modal analysis for predicting wind-induced dynamic responses of tall buildings. An improved LMS method, called the advanced linearized-mode-shape (ALMS) method, is developed in this paper by introducing torsional mode shape corrections to account for the partial correlation of torques over building height. The ALMS method has been incorporated into the accurate complete quadratic combination method in the coupled dynamic analysis to form a comprehensive procedure for the determination of equivalent static wind loads (ESWLs) for structural design of complex tall buildings. The improved accuracy in the prediction of generalized forces by the ALMS method has been validated by a 60-storey benchmark building with multiple-point simultaneous pressure measurements. A practical 40-storey residential building with significant swaying and torsional effects is presented to demonstrate the effectiveness of the proposed wind load and response analysis procedure based on the HFBB data. Copyright © 2010 John Wiley & Sons, Ltd.

Contemporary tall buildings with increasing height and slenderness are highly sensitive to the actions of wind. The structural design of modern tall buildings is generally governed by the need to provide adequate strength and stiffness against dynamic movement induced by strong wind. In addition to the strength-based safety design considerations, the major design effort of a tall building is related to the assessment of the wind-induced serviceability design requirements in terms of lateral drift and motion perception criteria. With tall buildings of today continuing to increase in height, the mitigation of wind-induced vibrations in tall buildings becomes a more critical challenge in the design synthesis process. This paper presents an integrated dynamic analysis and computer-based design optimization method for minimizing the structural cost of tall buildings subject to wind-induced serviceability acceleration design criteria. Once the optimal dynamic serviceability design problem is explicitly formulat...

Three-dimensional wind load effects on a tall building with X-shape are investigated based on measured synchronous surface pressures in a wind tunnel. The mean and root-mean-square storey force coefficients in the three primary directions, i.e. along-wind, crosswind and torsional wind, of the building are presented. Wind-induced response analysis has been carried out in time domain by using the step-by-step numerical integration method, and the occupant comfort performance of the practical 42-storey building is checked against the Chinese tall building design code. In the dynamic analysis, the buildings are modelled by a lumped mass system having three degrees of freedom at each floor level, i.e. two orthogonal translations and one rotation about a vertical axis. A new resultant displacement projection method is proposed to calculate the gust response factors (GRFs) along two orthogonal coordinate directions for design purpose. Not only can the calculated GRFs ensure the synchronization among the maximum resultant displacement and the maximum component displacements along X- and Y-axes, but also are capable of taking crosswind effects into account. Copyright © 2009 John Wiley & Sons, Ltd.

Modern tall steel buildings are wind sensitive and are prone to dynamic serviceability problems. Although wind tunnel techniques have emerged as valuable tools in providing reliable prediction of the wind-induced loads and effects on tall buildings, current design practice normally considers the wind tunnel-derived loads as constant static design loads. Such practice does not take into account the change in wind-induced structural loads while the dynamic properties of a building are modified during the design synthesis process. This paper presents a computer-based technique that couples together an aerodynamic wind tunnel load analysis routine and an element stiffness optimization method to minimize the cost of tall steel buildings subject to the lateral drift design criteria, while allowing for instantaneous prediction and updating of wind loads during the design synthesis process. Results of a full-scale steel building framework with the same geometric shape of the Commonwealth Advisory Aeronautical Research Council (CAARC) standard building indicate that not only is the proposed technique able to produce the cost-effective element stiffness distribution of the structure satisfying the serviceability wind drift design criteria, but a potential benefit of reducing the design wind loads can also be achieved by the stiffness optimization method. Copyright © 2007 John Wiley & Sons, Ltd.

This paper describes a proposed wind-excited benchmark tall building incorporating three-dimensional lateral-torsional modes of vibration, which is typical of a significant number of modern tall buildings. A series of wind tunnel pressure tests were conducted on a 1:400 scale model to determine the translational and torsional wind forces acting on the benchmark building. A finite element 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 (ROS) using the state order reduction method. A numerical vibration control example was conducted to demonstrate the suppression of the wind-induced three-dimensional lateral-torsional motions using a bi-directional tuned mass damper (TMD) incorporating two magnetorheological (MR) dampers, one in each orthogonal direction, to act as a semi-active control system, referred to as a smart tuned mass damper (STMD). The optimal control forces generated by the MR dampers were obtained through the linear quadratic regulator (LQR) to minimize the storey accelerations. The formulation details, methodology and numerical simulation results are outlined in this paper.

Dynamic wind loads on tall buildings can be decomposed into three components, i.e. two translational components and one torsional component. When one component reaches its maximum, the other two components have low probability to take their maximum values. It is common to use combination coefficients for estimating the mean extremes of linearly combined wind loads. The traditional design practice for determining wind load combinations relies partly on some approximate combination rules and lacks a systematic and reliable method. Based on the high frequency force balance (HFFB) testing results, wind loads can be acquired in terms of time history data, which provides necessary information for the more rigorous determination of combination coefficients by probabilistic methods. In this paper, a 3D copula-based approach is proposed for determining the combination coefficients for three stochastic wind loads associated with a specific exceedance probability and a set of 3D realizable equivalent static wind loads (ESWLs) on tall buildings. Using the measured base moment and torque data by the HFFB wind tunnel test, a case study is presented to illustrate the effectiveness of the proposed framework to determine the dynamic wind load combinations and associated 3D realizable ESWLs on a full-scale 60-story building.

This paper presents a combined study of wind tunnel experiment and numerical simulation of the wind-induced pressures on the long-span roof of the Hangzhou East Railway Station Building. Wind tunnel tests were performed on a 1∶250-scale rigid model of the station building. Based on the measured pressure data, the third and fourth statistical moments of the pressure processes were evaluated to quantify the non-Gaussian nature of the wind-induced pressures on the station roof. Using the recently reported Hermite moment model, an analytical form of the non-Gaussian peak factor was proposed for a given hardening load process and was verified using numerical integration. The currently available simulation algorithm was revised to generate sample functions of skewed hardening load processes. The simulated pressure data samples provide a basis for the direct statistical analysis of extreme peaks. The peak factors for non-Gaussian wind load effects were estimated by employing various state-of-the-art meth...