Wind-induced Dynamic Response Research Articles

Wind-Induced Dynamic Response of Inter-Story Isolated Tall Buildings with Friction Pendulum Bearing Based on an Enhanced Simplified Model

Isolation technology, especially for base isolation, is increasingly being applied in earthquake-prone areas. To satisfy some special demands (such as prevention from seawater erosion of an isolation layer, story-adding retrofit of existing buildings, avoidance of collision between base-isolated tall buildings, and so on), the isolation layer sometimes has to be set in the middle of a building to constitute inter-story isolated buildings. This special structural form inevitably encounters strong wind loads during service life, and its wind-resistant performance deserves to be investigated. This study conducts the wind-induced vibration analysis of inter-story isolated tall buildings with friction pendulum bearing (FPB). The nonlinear time domain analysis model and statistical linearization method to compute the wind-induced response of FPB inter-story isolated tall buildings are addressed based on an enhanced simplified model. Considering the independence of the upper and lower structures, two structural design schemes for inter-story isolated tall buildings are provided. Their dynamic characteristics are analyzed, and wind-induced responses are compared. Finally, the accuracy of the statistical linearization method is verified. This study provides an important theoretical basis for the structural design and wind resistance of inter-story isolated tall buildings.

Study on Wind-Induced Dynamic Response and Statistical Parameters of Skeleton Supported Saddle Membrane Structure in Arching and Vertical Direction

Wind tunnel tests and numerical simulations are the mainstream methods to study the wind-induced vibration of structures. However, few articles use statistical parameters to point out the differences and errors of these two research methods in exploring the wind-induced response of membrane structures. The displacement vibration of a saddle membrane structure under the action of wind load is studied by wind tunnel tests and numerical simulation, and statistical parameters (mean, range, skewness, and kurtosis) are introduced to analyze and compare the displacement data. The most unfavorable wind direction angle is 0° (arching direction). The error between experiment and simulation is less than 10%. The probability density curve has a good coincidence degree. Both the test and simulation show a certain skewed distribution, indicating that the wind-induced vibration of the membrane does not obey the Gaussian distribution. The displacement response obtained by the test has good stability, while the simulated displacement response has strong discreteness. The difference between the two research methods is quantitatively given by introducing statistical parameters, which is helpful to improve the shortcomings of wind tunnel tests and numerical simulations.

Wind-Induced Response Assessment of CAARC Building Based on LBM and FSI Simulation

It is very important for the wind-resistant design of high-rise buildings to assess wind-induced vibrations efficiently. The Lattice Boltzmann Method-based Large Eddy Simulation and Fluid–Structure Interaction techniques are used to identify the surface wind pressure and wind-induced dynamic response of a CAARC standard high-rise building. Compared with wind tunnel tests, a detailed analysis of the accuracy of simulated wind pressures and base moments of the CAARC model are discussed under multiple wind direction angles. The differences between one-way and two-way Fluid–Structure Interaction simulations are compared under two different reduced wind velocities. The research results show that the simulated mean surface wind pressures of building under seven wind direction conditions have an error within 15% compared to probe measurements, and the average and root mean square base bending moments agree well with the wind tunnel tests. The top transverse wind-induced vibrations of the buildings are significantly larger when the reduced wind velocity reaches 4.6, indicating that aerodynamic damping effects on structural responses should not be overlooked. The research findings of this article provide valuable technical references for the application of LBM methods in the wind load effect assessments of high-rise buildings.

Formulation of justifiable wind loading distributions up tall buildings derived from HFFB measurements

For the general case of non-linear and combined sway and twist mode shapes, analysis of HFFB measurements gives rise to serious challenges and various techniques have been developed using significant assumptions. This is because it is not possible to directly obtain the distribution of varying fluctuating wind loads throughout the height of tall buildings. This paper proposes a straightforward HFFB-based wind load/twist distribution approach in the time domain to predict the wind-induced dynamic response of tall buildings. Using this framework, it is possible to overcome the deficiencies of mode shape correction factor approach, and the complexity and impracticality of alternative approaches for tall buildings. Two 1:300 scale rigid models of benchmark tall buildings, IAWE Buildings A and B, have been selected to perform a detailed wind tunnel investigation as subjects to evaluate this proposed HFFB approach study. Building A has complex 3D mode shapes combining sway and twist, whereas the simpler Building B has uncoupled linear mode shapes in sway and twist. The high frequency pressure integration (HFPI) wind tunnel technique was utilised to measure surface pressure information in separate tests to obtain the reference wind loading for validation of the HFFB predictions. Furthermore, a commonly used HFFB mode shape correction factor approach was used to estimate the dynamic wind responses which were compared to those from the proposed approach. From the comparison between the aerodynamic and dynamic wind results from proposed HFFB approach and reference HFPI results, it is found that the proposed HFFB approach can predict the vertical distributions of the wind forces and torque (wind loads) with acceptable accuracy for carrying out the conceptual stage of tall building design.

Stochastic stress response and dynamic reliability evaluation for transmission towers with semi-rigid behaviors

As a kind of typical wind-sensitive structure, transmission towers have attracted fast-growing attention in the field of their wind-induced dynamic response. Nevertheless, their dynamic response considering effects of semi-rigid connected joints and semi-rigid-constrained stability behaviors has not been investigated. To this end, based on the experimental and numerical study, this paper proposes a fitting formula for the stability coefficient of steel tube members with semi-rigid behaviors in transmission towers to determine the dynamic stress response. Then, the stiffness, mass, and damping matrices of steel-tube transmission towers (STTTs) with semi-rigid behaviors are determined to construct their stochastic dynamic finite element model. Subsequently, the integral form of the generalized density evolution equation is solved via a family of Dirac's sequences to conduct the stochastic stress response analysis for STTTs considering effects of semi-rigid connected joints and semi-rigid-constrained stability behaviors, and their dynamic reliability is evaluated by further introducing the extreme-value distribution method. Finally, an engineering example of an existing STTT is given, and the results indicate that the semi-rigid connected joints and semi-rigid-constrained stability behaviors would significantly affect the stochastic stress response and dynamic reliability of STTTs. Accordingly, taking into account semi-rigid connected joints and semi-rigid-constrained stability behaviors may be more applicable for analysis and design of STTTs.

Dimension Reduction Method-Based Stochastic Wind Field Simulations for Dynamic Reliability Analysis of Communication Towers

The communication tower is a lifeline engineering that ensures the normal operation of wireless communication systems. Extreme wind disasters are inevitable while it is in service. Two dimension-reduction (DR) probabilistic representations based on proper orthogonal decomposition (POD) and wavenumber spectral representation (WSR), say DR-POD and DR-WSR, were thus proposed in this study. In order to determine the least representative sample size that satisfies the engineering accuracy requirements, the simulation error and simulation duration of 10 simulation points distributed along the height direction of the communication tower under different representative sample numbers were compared. Furthermore, for the fluctuating wind field with different numbers of simulation points distributed along the height of the communication tower, the simulation accuracy as well as efficiency of the DR-POD and the DR-WSR were compared. Finally, a high-rise communication tower structure’s wind-induced dynamic response study and wind-resistance reliability analysis were performed utilizing an alliance of the probability density evolution method (PDEM) and two DR probabilistic models, taking 10 load points into account. The structural dynamic analysis illustrates that the reliability of the communication tower structure and the wind-induced dynamic response allying the two DR probabilistic models with the PDEM have outstanding consistency.

Full-scale monitored wind and response characteristics of a suspension bridge compared with wind tunnel investigations at the design stage

Structural health monitoring of long-span bridges makes it possible to assess the assumptions and considerations in the design stage of the structures through measurements of their structural response and environmental conditions. In wind-resistant design of long-span bridges, the wind-induced dynamic buffeting response is difficult to assess as the uncertainty in the loading and the structural and aerodynamic characteristics is high. In that case, one of the best sources of information is wind tunnel tests, in addition to field measurements and analytical considerations. However, it is unclear if such methods can provide reliable information for the designer since, typically, many uncertainties and assumptions are involved in such a process. Here, we evaluate the scaled full aeroelastic and terrain model tests carried out during the design stage of the Gjemnessund Bridge in Norway through comparisons with full-scale monitoring data spanning five years. The monitoring system and the data are presented along with the wind tunnel study. The results from both campaigns are analyzed and critically discussed, emphasizing implications for the wind-resistant design of long-span bridges.

Instability mechanism and failure criteria of large-span flexible PV support arrays under severe wind

Compared with independent flexible PV support, the entire structure force performance and transfer mechanism of inter-row cables and inter-span rods of flexible PV support arrays are more complex, it is easy to have large vibration or even instability failure under strong wind. In this study, the three-span and five-row flexible PV support array of a 66 MW Fishery-PV Complementary demonstration site in the eastern coastal region of China is used as the research object. The rigid body pressure measurement wind tunnel test was designed and carried out, and the wind pressure distribution characteristics of the PV panels surface were analyzed. A three-dimensional explicit dynamics model of the flexible PV support array considering inter-row cables and inter-span rods is established, and the wind-induced dynamic response characteristics and instability processes of the large-span flexible PV support array are effectively simulated. Finally, the instability mechanism of the large-span flexible PV support array is revealed, and the dual failure criteria based on structural deformation and energy increment are proposed. Results demonstrated that the maximum values of displacement and von Mises stress of the large-span flexible PV support array are concentrated in the 1st row of the span in the windward side. The array under 0° and 180° wind direction angles induces local instability and failure at wind speeds of 51 m/s and 46 m/s due to the failure of the 1st row of triangular rods and crossed diagonal rods on the windward side, respectively, and the rods instability mechanisms are Eulerian buckling mechanism and Limit point buckling mechanism, respectively. When the axial compression ratio [Δ] > 0.1 or the strain energy increment [ΔU] > 1.0 × 105J of the instability rod, the structure will be locally destabilized. This paper presents a systematic work around the wind-induced response and instability characteristics of the large-span flexible PV support array, the results are of significance for the engineering application of solar energy generation structures.

Wind induced coupling effects of transmission tower-line system at microtopography

The coupled and uncoupled Dynamic Finite Element Models (DFEMs) of the transmission tower-line system consisting of two towers and three spans of conductors and ground wires were built at the windward and crosswind slope of a cosinoidal hill. The acceleration ratios of mean wind profiles of cosinoidal mountains were summarized from previous studies, then the mean wind profile over the windward, crosswind and leeward slopes were revised. The wind loads acting on the transmission tower-line system were calculated based on the revised profile. The wind-induced dynamic responses of the coupled and uncoupled DFEMs were detected, and the coupling effects on reaction force of hanging points, displacements and accelerations at the tower top, axial forces of main rods and wind-induced vibration coefficients were analysed. The results show that due to the lack of the TMD-like effect, the uncoupled system is more sensitive to wind load and has significant wind-induced vibration compared to the coupled system, making the three-dimensional force of the hanging point, displacements and accelerations at the tower top, axial forces of main rods increasing, but the wind-induced vibration coefficients change little. Generally, the coupling effects of the tower-line system are significant. Ignoring it will make the structural design of transmission towers conservative.

Frequency calculation method and wind-induced dynamic response of cable net façades considering the façade stiffness

In this study, a frequency formula for cable net façades that considers façade stiffness is proposed, and the effect of the façade stiffness on the dynamic behavior is analyzed. Initially, a theoretical formula based on membrane theory is derived for calculating the frequency of cable net façades while neglecting façade stiffness. Moreover, a total of 720 detailed finite element (FE) models of cable net façades with various parameters are established in ANSYS finite element software. The effects of glass thickness, cable spacing and cable force on frequency are analyzed with the detailed FE models. Based on the theoretical formula and detailed FE models, a fitted frequency formula that includes the façade stiffness is further proposed to calculate the first-order mode, which is the prominent mode. Furthermore, the effect of the façade stiffness on the dynamic response of the structure, including the cable force and displacement, is researched under excitation by wind loads based on time history analysis. The results show that the influence of façade stiffness on the frequency and dynamic response gradually decreases as the number of cable net grids increases. When the grid number is above 10, the impact can be ignored. In addition, the fitted formula can be used when the grid number is under 10, and when the number of grids exceeds 10, the theoretical formula can be applied. Considering this simplification, a simplified FE model is proposed in engineering design for grid numbers exceeding 10. When the grid number is less than 10, it is recommended to adopt a detailed FE model designed to avoid errors in structural design.

Long Short-Term Memory Network for Predicting Wind-Induced Vibration Response of Lightning Rod Structures

Lightning rod structures are susceptible to wind loads due to their high slenderness ratio, high flexibility, and light weight. The wind-induced dynamic response of a lightning rod is critical for structural safety and reliability. The traditional methods for this response, including observation and simulation, focus on structural health monitoring (SHM), wind tunnel tests (WTTs), or fluid–structure interaction (FSI) simulations. However, all these approaches require considerable financial or computational investment. Additionally, problems such as data loss or data anomalies in the sensor monitoring process often occur during SHM or WTTs. This paper proposes an algorithm based on a long short-term memory (LSTM) network to predict the wind-induced dynamic response and to solve the problem of data link fracture caused by abnormal sensor data transmission or wind-induced damage to lightning rod structures under different wind speeds. The effectiveness and applicability of the proposed framework are demonstrated using actual monitoring data. Root-mean-squared error (RMSE), determination of coefficient (R2), variance accounted for (VAF), and the refined Willmott index (RWI) are employed as performance assessment indices for the proposed network model. At the same time, the random forest algorithm is adopted to analyze the correlation between the data of the different measurement points on the lightning rod structure. The results show that the LSTM method proposed in this paper has a high accuracy for the prediction of “missing” strain data during lightning rod strain monitoring under wind speeds of 15.81~31.62 m/s. Even under the extreme wind speed of 31.62 m/s, the values of RMSE, MAE, R2, RWI and VAF are 0.24053, 0.18213, 0.94539, 0.88172 and 0.94444, respectively, which are within the acceptable range. Using the data feature importance analysis function, it is found that the predicted strain data of the measurement point on the top part of the lightning rod structure are closely related to the test strain data of the two adjacent sections of the structure, and the effect of the test strain data of the measurement points that are far from the predicted measurement point can be ignored.

Estimation of wind-induced response of large membrane structures with nonlinear motion-induced aerodynamic force and nonlinear geometric stiffness

Wind-induced dynamic response for large membrane structures with consideration of the coupling influences of nonlinear motion-induced aerodynamic force and nonlinear geometric stiffness is analytically evaluated in this study. By utilizing the equivalent nonlinear system approach, the Fokker-Planck-Kolmogorov equation of the membrane structures is derived, and the analytical response solutions, including probability density function, root-mean-square value, kurtosis, peak response, and peak factor, are presented. The accuracy of the proposed analytical solutions is checked by the numerical results obtained with the fourth-order Runge-Kutta approach. The findings reveal that vortex-induced vibrations occur at high wind speed regions due to the effect of nonlinear negative aerodynamic damping. Additionally, the geometric stiffness nonlinearity caused by large deformation is found to be significant for reducing the dynamic response amplitude in membrane structures. This study proposed herein presents an effective analytical approach for predicting the aero-elastic response of such flexible structures subjected to wind loads.

Wind Interference Effect of Neighbouring Square Buildings in Rhombic Arrangement on an Octagonal Building

Four square plan shaped tall buildings of the same height and lateral dimension are positioned at the vertices of a rhombus. The octagonal plan shaped tall building of same height is placed at the centroid of the rhombus. The wind-induced responses of the octagonal plan shaped tall building for specified interference cases are compared with that of the isolated cases. The octagonal plan shaped principal building is exposed to atmospheric boundary layer wind flow. The wind angle varies from 0° to 90° at an interval of 15° for both isolated and interfering conditions. Computational fluid dynamics is implemented to simulate the effect of wind-structure interaction on the principal and neighbouring buildings in the boundary layer wind flow. The wind-induced static responses like drag and lift coefficients, pressure coefficients for isolated and interference cases are evaluated and compared graphically. The responses of isolated and interference cases vary significantly with the varying wind incidence angle. The dynamic behaviour of wind is also thoroughly investigated to identify the adverse local effect on the different faces of the octagonal building. As the characterisation of wind-induced dynamic responses, peak pressure coefficients and power spectral densities are evaluated and plotted accordingly. The peak pressure coefficients are plotted against mean pressure coefficients. The power spectral densities for different interfering cases are compared with the isolated case. Significant variation in power spectral densities is observed in some cases, which portrays the different characteristics for formation and shedding of the vortices in the wake of the octagonal building. The comparison of various dynamic responses between isolated and interfering cases highlights the interference by the square plan shaped buildings.

The Interference Effects of Wind Load and Wind-Induced Dynamic Response of Quayside Container Cranes

Strong wind has caused damage to group-arranged quayside container cranes in terminals and ports in recent years. Interference may amplify the wind loads in some cases. However, the interference effect among cranes has rarely been studied. In this study, high-frequency force balance tests were conducted to obtain the wind load of isolated and group-arranged container cranes. The results of the computational fluid dynamics simulation were validated by wind tunnel tests and provided the mean wind loads of all 15 types of member cranes. According to the results from wind tunnel tests, the fluctuating wind loads of each member were generated using the weighted amplitude wave superposition method. Based on dynamic finite element methods, the wind-induced responses were obtained considering the interference effect. It was found that the interference effect is the combined effects of both the shielding effect and the amplification of turbulence. Although in some cases the fluctuating and peak wind loads can increase by up to 16% and 6%, respectively, those in the most unfavorable cases are reduced by the interference effect. The interference factor for extreme nodal deformation is 0.56 and 0.69. The interference effect in container cranes mainly appears as a shielding effect, reducing the wind loads and response of the structures in unfavorable cases.

Experimental study of wind-induced dynamic response and collapse of a mechanically-attached membrane roofing system installed on metal substrate of flat-roofed low-rise steel building

This paper investigates the wind-induced dynamic response at design wind speed and the collapse of a mechanically-attached membrane roofing system installed on metal substrate of flat-roofed low-rise steel building, based on a wind pressure loading test using full-scale assembly specimens. Three kinds of waterproofing membranes with different mechanical properties are tested. The wind loads employed in the test are generated by using the time histories of wind pressure coefficients on the roof of a flat-roofed low-rise building with low parapets, which were obtained from a wind tunnel experiment. Both the temporal and spatial variations of wind pressures are reproduced by using three Pressure Loading Actuators (PLAs). A step-wise pressure loading test commonly employed in the conventional wind-resistant performance evaluation in Japan is also carried out for a comparative purpose. The results indicate that the fasteners connecting the disks with the metal substrate are subjected to not only vertical uplift forces due to negative wind pressures (suctions) but also horizontal forces related to the membrane deformation. The maximum value of horizontal force is nearly equal to that of the vertical force. Although the general correlation between vertical and horizontal forces is not so high, the maximum values of these forces may occur almost simultaneously. Larger the membrane deformation, larger the horizontal forces are. The horizontal forces reduce the failure loads and affect the failure modes significantly. Therefore, the effect of horizontal forces should be considered in the evaluation of wind-resistant performance of mechanically-attached membrane roofing systems. The failure load under step-wise pressure is generally smaller than that under fluctuating wind pressures. Therefore, the conventional step-wise pressure loading test can be used as a simple method for evaluating the failure load of the roofing system on the safer side.

Effect of time-variant structural modal parameters on accurate estimation of wind-induced dynamic responses of high-rise buildings during typhoons

Structural modal parameters of high-rise buildings during severe winds generally exhibit time-variant features, which conflicts with the assumption adopted in the wind-resistant design procedure that the modal parameters are time-invariant values. This may lead to inaccurate estimation of wind-induced structural dynamic responses, thus deteriorating the reliability of structural design of high-rise buildings. To address this issue, this paper first evaluates the time-variant modal parameters of a 600-m-high skyscraper based on building accelerations measured during Super Typhoon Mangkhut. Then, the identified time-variant modal parameters are combined with the wind loads estimated from wind tunnel test on a 1:500 scaled model of the skyscraper to reproduce the typhoon-induced building accelerations. The results show that the reproduced accelerations based on the time-variant modal parameters agree well with the field-measured ones. Moreover, a comparative study between adoption of the time-variant modal parameters and time-invariant modal parameters is conducted, which shows that the former case provides more accurate estimation of the building dynamic responses during the extreme typhoon event. This paper aims to explore an effective means for precise evaluation of typhoon-induced dynamic responses of high-rise buildings.

A practical combination method for wind-induced responses of high-rise buildings: Based on the correlation of extremes

This study proposes a practical three-dimensional combination method for wind-induced responses of high-rise buildings. Five high-rise buildings with different side ratios are considered, where the base shears in two translational directions and base torques of each model are measured by the high-frequency force balance technique. The wind-induced dynamic responses are then calculated based on the measurement. The wind-induced extreme response along one direction and the simultaneously observed wind-induced responses along the other two directions are systematically analyzed, through which the combination factors are determined from a probability view. The factors are then validated by comparing with those specified in several proceeding international codes and standards. The effects of the resonant component, building side ratio, and building surroundings on the combination of wind-induced responses are investigated. The results show that the correlation of the extremes is considerably different from the correlation of time histories. Generally speaking, neglecting the resonant component will underestimate the combination factors. The building side ratio has substantial influence on the combination factor. In the end, the proposed method is employed to calculate combination factors of an actual high-rise building to verify its application in engineering practice.

Predicting wind-induced structural response with LSTM in transmission tower-line system

Wind-induced dynamic response of the nonlinear structure is critical for the structural safety and reliability. The traditional approaches for this response including observation or simulation focus on the structural health monitoring, the experiment, or finite element model development. However, all these approaches require high cost or computational investment. This paper proposes to predict the wind-induced dynamic response of the nonlinear structure with a novel deep learning approach, LSTM, and applies this in a structural lifeline system, the transmission tower-line system. By constructing the optimized LSTM architectures, the proposed method applies to both the linear structure, the single transmission tower and the nonlinear structure, the transmission tower-line system, with promising results for the dynamic and extreme response prediction. It can conclude that the layers and the hidden units have a strong impact on the LSTM prediction performance, and with proper training data set, the computational time can significantly decrease. A comparison surrogate model developed by CNN is also utilized to demonstrate the robustness of the LSTM-based surrogate model with limited data scale.

Monitoring of wind effects on a wind-sensitive hybrid structure with single-layer cable-net curtain walls under Typhoon Muifa

As a new type of building structure, the single-layer cable net (SL cable net) is widely used in many large landmark buildings with modern glass curtain walls. As a kind of wind-sensitive structure, the wind effects on the SL cable net is a problem that cannot be ignored. Therefore, a field measurement was carried out at the China Maritime Museum during Typhoon Muifa. The wind field characteristics and the wind-induced dynamic responses of the SL cable net during this typhoon were well studied. The relationship between the wind characteristics and the dynamic characteristics was analyzed. It was found that the vibration intensity of the SL cable net, unlike that of high-rise buildings, is not correlated with the time-varying mean but is positively correlated with the fluctuating wind speed. By using the method SSI and NExT, it was found that the low-order frequencies of the SL cable net are insensitive to the time-varying mean but have a negative correlation with the RMS fluctuating wind speed. The vibration of the SL cable net was proved to be a more direct cause of the phenomenon of frequency softening. Reasons of this phenomenon were discussed in this paper. At last, damping ratios of the SL cable net were studied and found to be insensitive to the structural vibration or wind speed in this paper.

A comparative study of wind-induced dynamic response models of long-span bridges using artificial neural networks, support vector regression and buffeting theory

Long-span cable-supported bridges are structures susceptible to high dynamic responses due to the buffeting phenomenon. The current state-of-the-art method for buffeting response estimation is the buffeting theory. However, previous research has shown discrepancies between buffeting theory estimates and full-scale measured response, revealing a weakness in the theoretical models. In cases where wind and structural health monitoring data are available, machine learning algorithms may enhance the buffeting response estimation speed with less computational effort by bypassing the analytical model’s assumptions. In this paper, multilayer perceptron and support vector regression models were trained with synthetic and full-scale measured data from the Hardanger Bridge. The analytical response was also computed from buffeting theory applied to a finite element model of the bridge, and the estimates are compared. The prediction accuracy was evaluated with the normalized root mean square error, the mean absolute percent error and the coefficient of determination (R2). The machine learning models trained with synthetic datasets achieved very high accuracy with normalized root mean square errors ranging from 1.46E-04 to 7.21E-03 and are therefore suitable for efficient surrogate modeling. Further, the support vector regression model trained with the full-scale measured dataset achieved the best accuracy compared with the other methods.