Aerodynamic Mitigation Research Articles

Aerodynamic mitigation of low-rise building with complex roof geometry

During strong wind events, building roofs are subjected to high wind uplift forces (suctions), which often lead to severe roofing component damage, or even roof total failure, flying debris, and water intrusion, hence, interior damages. Typical roof shapes (e.g., gable and hip) are generally designed using provision codes and standards to accurately estimate peak load impacting the roofs during wind events for design purposes. Complex roof geometry can be efficiently examined using wind tunnel testing and computational modeling to provide quantitative assessment for wind to narrow down the design alternatives and to examine the improvement gained from mitigation techniques. In this study, an isolated low-rise building with a complex roof shape is examined using large eddy simulation (LES) to numerically assess wind load prediction by validating it with wind tunnel results. This study presents two roof modification scenarios using parapets added to roof corners and ridgelines to displace the flow from the separation locations to reduce the wind impact on the roof. The current study aims to 1) evaluate wind load on an isolated low-rise building with complex roof geometry for various angles of attack and 2) mitigate the roof aerodynamically using parapets, added corners, and ridgeline to reduce the wind impact on the roof. The validation shows that both the mean and RMS of the pressure coefficients are in good agreement with the wind tunnel results. The research results suggest that parapets with 500 mm height located at the corner and edges of complex roof geometry can effectively reduce extreme corner suction by 29% and roof uplift by 5.6%.

Investigation of Vortex-Induced Vibration of Double-Deck Truss Girder with Aerodynamic Mitigation Measures

The long-span double-deck truss girder bridge has become a recommend structural form because of its good performance on traffic capacity. However, the vortex-induced vibration (VIV) characteristics for double-deck truss girders are more complicated and there is a lack of related research. In this research, wind tunnel tests were utilized to investigate the VIV characteristics of a large-span double-deck truss girder bridge. Meanwhile, the VIV suppression effect of the aerodynamic mitigation measures was measured. Furthermore, the VIV suppression mechanism was studied from the perspective of vortex shedding characteristics. The results indicated that the double-deck truss girder had a significant VIV when the wind attack angles were +3° and +5°. The aerodynamic mitigation measures had an influence on the VIV response of the double-deck truss girder. The upper chord fairing and lower chord inverted L-shaped deflector plate played a crucial role in suppressing VIV. Numerical analysis indicated that vortex shedding above the upper deck or in the wake region may dominate vertical VIV, while vortex shedding in the wake region of the lower deck may dominate torsional VIV. The upper chord fairing and lower chord inverted L-shaped deflector plate disrupted the original vortex shedding pattern in both regions, thereby suppressing VIV. This research can provide a foundation for bridge design and vibration suppression measures for large-span double-deck truss girder bridges.

Aerodynamic mitigation by corner modification on square model under wind loads employing CFD and wind tunnel

This paper explores a recent application of the computational fluid dynamics technique “CFD” for wind analysis and its comparisons with the conventional wind tunnel experimentations. This study is centered on the wind response of square and corner cut-shaped building models and its optimization caused by the variation of the wind incidence angle. Extensive rigid model experiments of two building models of length scale 1:100 have been performed in the boundary layer wind tunnel. The numerical analysis has been carried out with the standard k-ε turbulence model to evaluate the force coefficients, base moments, power spectra, external surface pressure coefficients, and flow field characteristics of the models with variable wind angles of incidence. The comparisons between experimental results and CFD analysis suggest the computational approach's viability in wind analysis of tall structures efficiently and accurately. A case study of aerodynamic mitigation by corner cut suggests minor modification techniques performance, efficiency, and limitations.

Case study of vortex-induced vibration and mitigation mechanism for a long-span suspension bridge

The wind-induced vibration of long-span bridges mainly manifests as flutter, galloping, vortex-induced vibrations (VIVs), buffeting, etc. Among these, VIVs cause vertical or torsional single-mode vibrations of the main girder; these affect the comfort of drivers or pedestrians on the bridge when vortex-induced resonance occurs. In this study, field measurements, numerical simulations, and wind tunnel tests were used to systematically investigate triggering mechanism during the sudden first and secondary VIV phenomena of Humen Bridge, along with the structural mode and damping characteristics and VIV aerodynamic mitigation effects, etc. The results show that the sudden first VIV was caused by the temporary installation of water-filled barriers, as these changed the aerodynamic configuration of the box girder; the decisive removal of these water-filled barriers can effectively suppress the VIV amplitude to some extent. The succedent secondary VIV was caused by the reduction of the structural damping; therefore, aerodynamic control and damping control measures are proposed. The aerodynamic control measures include the implementation of suppressor plates on the top of handrails and removal of the maintenance rails under the girder, whereas the structural damping control measures involve the successive installation of tuned-mass damper (TMD) to compensate for the reduced damping owing to the former large-amplitude VIV performance. After verification based on reduced-scale model wind tunnel tests, the aerodynamic control measures and structural damping control measures are successfully adopted and applied to Humen Bridge. These measures are shown to effectively suppress VIVs, as confirmed via succedent long-term on-the-spot observations.

Experimental study on wind-induced vibration and aerodynamic mitigation measures of a building over 800 meters

The new-generation high-rise buildings are taller and more flexible than before. Rigid model and aeroelastic model tests of a proposed steel super high-rise building with a height of 838 m were carried out in two simulated typical wind fields defined in the Chinese code [1] and the ISO standard (ISO 4354) in an atmospheric boundary layer wind tunnel. The wind pressure distributions of the building were obtained through the rigid model tests and then the wind-induced vibration responses of the building were calculated. Through the aeroelastic model test, the vibration responses of the building, which naturally include the wind–structure coupling effects, were directly obtained. The test results shows that strong crosswind vortex-induced resonance may appear at high wind speeds. Based on these results, the crosswind aerodynamic damping of the building was then studied. Finally, seven aerodynamic measures for controlling the wind-induced vibrations of the building were proposed and tested. The results show that the seven proposed aerodynamic measures can reduce the dynamic responses of buildings in different degrees.

Flutter performance optimization of a long-span truss girder bridge in mountainous canyon

Steel truss stiffening girders are widely used when designing long-span bridges in mountainous areas owing to their distinct characteristics compared to the streamlined box girder. However, natural wind in mountainous areas is very complex with high turbulence and large attack angles which adversely affect the flutter performance of long-span bridges with truss girders. Aerodynamic countermeasures are widely adopted to improve flutter performance. This paper studies the flutter performance and the effects of various aerodynamic countermeasures on the flutter improvement of a 1060 m truss-stiffened girder suspension bridge spanning mountainous canyon by wind tunnel tests of the sectional model and full-bridge model. First, sectional model tests with the original girder section were carried out under various wind attack angles. Subsequently, to improve the flutter stability of the bridge under the most unfavorable wind attack angle, several aerodynamic countermeasures including central upper stabilizer, horizontal stabilizer, combined central upper and horizontal stabilizers, and sealed central traffic barrier were proposed and sectional model tests with optimized girders were conducted. The results show that the aerodynamic mitigation effect of the central upper stabilizer, horizontal stabilizer, as well as combined measure, is closely related to the geometric dimension of the stabilizing plate. It is found that large geometric dimensions effectively increase the flutter critical wind speed of the truss girder. Considering sealed central traffic barrier measure, the smaller ventilation rates result in larger flutter critical wind speed of the girder. The sealed central traffic barrier measure with a 50 % ventilation rate is deemed as the most optimal aerodynamic countermeasure in consideration of aesthetics, economy, and safety. Finally, the effectiveness of optimal countermeasure is validated through an aeroelastic full-bridge model test. The research is conducted to provide references on flutter performance optimization of similar bridges in the future.

A knowledge‐enhanced deep reinforcement learning‐based shape optimizer for aerodynamic mitigation of wind‐sensitive structures

AbstractStructural shape optimization plays an important role in the design of wind‐sensitive structures. The numerical evaluation of aerodynamic performance for each shape search and update during the optimization process typically involves significant computational costs. Accordingly, an effective shape optimization algorithm is needed. In this study, the reinforcement learning (RL) method with deep neural network (DNN)‐based policy is utilized for the first time as a shape optimization scheme for aerodynamic mitigation of wind‐sensitive structures. In addition, “tacit” domain knowledge is leveraged to enhance the training efficiency. Both the specific direct‐domain knowledge and general cross‐domain knowledge are incorporated into the deep RL‐based aerodynamic shape optimizer via the transfer‐learning and meta‐learning techniques, respectively, to reduce the required datasets for learning an effective RL policy. Numerical examples for aerodynamic shape optimization of a tall building are used to demonstrate that the proposed knowledge‐enhanced deep RL‐based shape optimizer outperforms both gradient‐based and gradient‐free optimization algorithms.

High Reynolds number aerodynamic testing of a roof with parapet

Aerodynamic testing was executed on a large-scale building with two distinct aspect ratios (1:6 and 1:3), at a large open-jet facility, Louisiana State University (LSU). To illustrate, a 1:15 scale test model was extensively investigated by experimental testing at a high Reynolds number (~2.3 × 107). The objective was to understand the performance of parapets in reducing the magnitude of localized and area-averaged roof pressures. Through analogy with bare-roof and several parapet configurations, the paper explores the performance of parapet walls and why they can be employed in aerodynamic mitigation. The results suggest installing a parapet wall will act as an aerodynamic mitigation device to reduce negative (uplift) loads. Large-scale testing indicates that the taller the parapet, the higher the reduction in mean and fluctuating pressures. However, depending on the roof’s aspect ratio, there is an optimal parapet height. The study concludes that 40–50% reductions in roof pressures can be achieved with parapets. Along the same lines, to yield high reductions in roof pressures, the parapet height is a key parameter. Short parapets may have low performance under conical vortices. The importance of the current study is that parapets, as well as other architectural features, are widely considered difficult to investigate by small-scale testing, at low Reynolds numbers, the leading cause of discrepancies between the laboratory and field measurements. Consequently, the current paper contributes to knowledge useful to explain the role of parapets in reducing aerodynamic pressures, for buildings to withstand wind loads at high Reynolds numbers.

Aerodynamic performance of Π-shaped composite deck cable-stayed bridges including VIV mitigation measures

This study systematically investigates the influence of the cross-sectional aspect ratio (B/H) and four different aerodynamic mitigation measures, i.e., the fairing, lower central stability plate, inverted L-shaped edge plate, and lower horizontal edge plate, on the performance of cable-stayed bridges, with π-typed composite deck, i.e., π section, due to vortex-induced vibrations (VIV). The study utilized wind tunnel tests and limited CFD simulations by varying bridge dimensions. First, based on a survey of existing cable-stayed bridges with the π-typed composite deck, three-section models with different aspect ratios were studied and their corresponding vibration characteristics for the vertical and torsional VIVs were analyzed. Then, the vibration suppression effects of mitigation measures with several variants in shape were investigated to determine an effective mitigation measure, i.e., with favorable aerodynamic stability, for the π section deck. The vibration suppression mechanism for three selected cases was further assessed using numerical simulation. The results show that: (a) for the π section model with the aspect ratio in the range of 9.05–11.96, increasing the ratio value will delay the onset wind speed of the vertical and torsional VIVs; (b) In the case of a low ratio of the torsional frequency to vertical bending frequency, there are often special phenomena where the vertical and torsional vibrations coexist. However, a larger aspect ratio would result in more independent vertical and torsional vibrations; (c) Regarding the vibration suppression effect, based on the limited studied cases, a small fairing can be superior to large fairings; (d) Different forms of the lower central stability plate have a good suppression effect on the vertical VIV; (e) The use of inverted L-shaped edge plate with a ​= ​23H and b ​= ​12H is identified to result in the best vibration suppression for both the vertical and torsional vibrations among the considered mitigation measures, where a and b are the size parameters of the inverted L-shaped edge plate; and (f) The lower horizontal edge plate cannot effectively improve the torsional VIV performance. This study offers guidance on the performance of composite cable-stayed bridge with the π section in isolation and equipped with mitigation measures to aid in the engineering design practice.

Experimental and numerical studies on the vortex-induced vibration of two-box edge girder for cable-stayed bridges

Due to the blunt aerodynamic configuration, the edge-girder bridge deck may sustain severe vortex-induced vibrations (VIVs) that adversely affect bridge usability and security. In the present study, the VIV performance and the related aerodynamic mechanism of the two-box edge girder for a cable-stayed bridge are systematically investigated. Based on the flow pattern and vortex structure around the section simulated by computational fluid dynamics, it is inferred that the aerodynamic interactions of the large-scale vortices under the deck and the shedding vortices in the wake zone periodically change the fluctuating pressures on the section and induce the vibrations of the deck. Moreover, several aerodynamic mitigation countermeasures are designed. Their effects on the vertical VIV are experimentally investigated in detail. It is found that the vertical VIVs are considerably suppressed at different attack angles (−3°, 0°, and +3°) by installing the mini-triangular wind fairings, which can satisfy the bridge wind-resistant design requirements. Further numerical simulations show that after the installation of the effective countermeasures, vortex shedding in the wake zone is mitigated, and the strengths and distortions of large-scale vortices around the upper and lower surfaces of the section also decrease, thereby the vertical VIV is suppressed effectively.

An alternative aerodynamic mitigation measure for improving bridge flutter and vortex induced vibration (VIV) stability: Sealed traffic barrier

This study proposes an alternative aerodynamic mitigation measure, i.e., sealed traffic barrier, for bridges and verifies its efficacy in improving the flutter and vortex induced vibration (VIV) stability of bridges through wind tunnel tests for three distinctive real-world bridge projects. The results show that: (1) The measure of the sealed traffic barrier with regular intervals along the bridge deck has a significant influence on the flutter and VIV performance of the bridge. Thus, a reasonable design of the traffic barrier can simultaneously improve the bridge’s flutter and VIV stability; (2) The sealed traffic barrier with vertical intervals along the bridge can effectively suppress the vertical VIVs of the bridge, while the sealed traffic barrier without vertical intervals, i.e., configured continuously along the bridge, has a better vibration suppression effect on the torsional VIV than that on the vertical VIV; (3) This proposed measure installed on both sides of the bridge deck imposes favorable suppression effect for the flutter vibration, similar to the upward central stabilizer. In case with the sealing form fixed, but a reduced height, for the barrier, the flutter stability at different wind attack angles is slightly decreased; and (4) In certain scenarios, increasing the ventilation rate of the traffic barrier results in an increase for the flutter critical wind speed at positive wind attack angles, but a decrease for the flutter critical wind speed at negative wind attack angles. This aerodynamic mitigation measure has been successfully applied to more than ten other bridge projects based on the wind tunnel tests by the leading authors, offering a reliable approach in improving both flutter and VIV for bridges.

Aerodynamic Mitigation of Wind Uplift on Low-Rise Building Roof Using Large-Scale Testing

During strong wind events such as hurricanes and thunderstorms, building roofs are subjected to high wind uplift forces (suctions), which often lead to severe roofing component damage and possibly, water intrusion. It is therefore crucial to accurately estimate peak suctions (negative pressures) on roofs for design purposes and to develop mitigation devices to reduce wind uplift and possible damage. Past research suggests that mitigation devices, in various forms and configurations, can significantly reduce wind effects on buildings’ roofs. Perforated parapets have been shown by many researchers to be one of the most effective and low-cost mitigation devices for reducing roof suction. However, such devices contain perforations of critical functionality that may be Reynolds number Re dependent. Therefore, it is essential to study their functionality and possible Re dependency in wind tunnel testing. This paper focuses on investigation of Reynolds number Re similitude aspects of porous devices and large-scale model testing of discontinuous porous parapets to estimate their roof uplift reduction efficacy that would be representative of the prototype (full-scale) conditions. Large scale (1:8) experiments were implemented at the 12-Fan Wall of Wind Experimental Facility (WOW) at Florida International University (FIU) to achieve adequate local Reynolds number Re to ensure realistic results. In this study, a relatively smaller ratio of parapet height to roof height has been considered as compared to previous studies. The paper delineates the step-by-step design of the parapets based on kinematic similitude requirements cited in the literature. The goal was to achieve a discontinuous porous parapet design that provides similar uplift reduction efficacy as compared to those reported in the literature, but with lower height and smaller length to ensure cost-effectiveness, ease of installation, and architectural aesthetics of the retrofitted building. The effects of perforated parapets on both individual tap and area-averaged pressure coefficients were explored. The results indicated a maximum of 45% reduction in individual tap peak pressure coefficients at the corner roof and a 40% reduction in area-averaged peak pressure coefficients. The study showed that low-height ratio perforated parapets could be as effective as those reported in the literature with higher height ratios.

A multi-fidelity shape optimization via surrogate modeling for civil structures

Shape optimization serves as a powerful tool to reduce wind effects on buildings. Past studies have demonstrated the superiority of the shape tailoring technique in aerodynamic mitigation through recessing or chamfering building corners, etc. Nonetheless, conventional approaches highly rely on wind tunnel experiments for which only a limited number of candidate geometries are tested to identify the best-performing one. In an attempt to globally and automatically explore the optimal geometry, the shape optimization via surrogate modeling is introduced in this study. Particularly, CFD is employed for calibration of the surrogate model. The CFD analyses can be conducted either through low-fidelity simulations such as RANS model, or through high-fidelity ones including LES. The low-fidelity model can provide a large ensemble for surrogate calibration, yet it suffers from the lack of accuracy. On the other hand, the high-fidelity model exhibits satisfactory accuracy, while it can only accommodate a small ensemble which may result in a large sampling error in the surrogate calibration. In order to take advantages of the merits of two types of CFD models, a multi-fidelity surrogate modeling is investigated in this research to guarantee the model accuracy as well as to maintain the computational efficiency.

Retrofitting building roofs with aerodynamic features and solar panels to reduce hurricane damage and enhance eco-friendly energy production

Wind-induced negative pressure on roofs of low-rise buildings is a major source of losses and community disruption. Vortex suppression technologies may reduce wind loads on buildings; however, it is challenging to implement an effective strategy to reduce wind loads on roofs with minimal loads on the mitigation feature itself. In this paper, the performance of different aerodynamic mitigation features is investigated in a comparative study. The results show that solar panels are relatively effective in reducing wind-induced uplift forces on a flat roof. Compared with all mitigation features presented, the airfoil is the most effective in reducing uplift loads, with promises to proceeding research in this area. In addition, the study investigates wind impact on a gable roof building with different configurations of solar panels, to reduce wind-induced loads on the host building while maintaining a visually appealing installation to permit broad usage and application. Pressure coefficients on roofs and solar panels from both computational fluid dynamics (CFD) simulations and laboratory experiments are compared. The study shows that the optimal roof/solar panel combination reduces wind loads on low-rise buildings, i.e. improves the performance, in addition to providing ecofriendly energy especially when power outage is expected.

Aerodynamic mitigation of wind-induced uplift forces on low-rise buildings: A comparative study

Negative pressures on roofs of low-rise buildings are a major source of losses and community disruption during windstorms. The main driver for negative pressures is the fact that buildings are bluff bodies that cause flow separtion, compared to streamline objects such as an airplane wing. Consequently, the separated flow may create conical vortices that can significantly increase wind-induced uplift loads on roofs. Although vortex suppression technologies play a role in reducing wind loads on buildings, the challenge is related to exploring techniques that can reduce loads on roofs and the mitigation features themselves. In this paper, several aerodynamic mitigation techniques/features are proposed and tested by computational fluid dynamics (CFD) simulations, in a comparative study to permit selection among different potential solutions. Modifications to eliminate the sharp corners that cause flow separation and uplift forces are carried out. Different aerodynamic mitigation features including barriers, circular edges, inclined edges and airfoil edges are investigated. The study explores mitigation devices that not only can reduce wind-induced uplift loads on roofs, but also have minimum drag and lift forces. The results show that the slope-in features, representatives of solar panels for green energy production, are effective in reducing wind-induced uplift forces. In fact, having solar panels on buildings can be a feasible solution, especially when there is a potential for power outage due to windstorms. Such features, among other devices, can potentially protect roofs under windstorms, creating economic and green buildings. In addition, compared to all mitigation features presented in the current study, the airfoil produced the minimum uplift loads, with promises to proceeding research in this area.

Influence of Turbulence, Orientation, and Site Configuration on the Response of Buildings to Extreme Wind

Atmospheric turbulence results from the vertical movement of air, together with flow disturbances around surface obstacles which make low- and moderate-level winds extremely irregular. Recent advancements in wind engineering have led to the construction of new facilities for testing residential homes at relatively high Reynolds numbers. However, the generation of a fully developed turbulence in these facilities is challenging. The author proposed techniques for the testing of residential buildings and architectural features in flows that lack fully developed turbulence. While these methods are effective for small structures, the extension of the approach for large and flexible structures is not possible yet. The purpose of this study is to investigate the role of turbulence in the response of tall buildings to extreme winds. In addition, the paper presents a detailed analysis to investigate the influence of upstream terrain conditions, wind direction angle (orientation), and the interference effect from the surrounding on the response of high-rise buildings. The methodology presented can be followed to help decision makers to choose among innovative solutions like aerodynamic mitigation, structural member size adjustment, and/or damping enhancement, with an objective to improve the resiliency and the serviceability of buildings.

Pressure integration technique for predicting wind-induced response in high-rise buildings

This paper presents a procedure for response prediction in high-rise buildings under wind loads. The procedure is illustrated in an application example of a tall building exposed to both cross-wind and along-wind loads. The responses of the building in the lateral directions combined with torsion are estimated simultaneously. Results show good agreement with recent design standards; however, the proposed procedure has the advantages of accounting for complex mode shapes, non-uniform mass distribution, and interference effects from the surrounding. In addition, the technique allows for the contribution of higher modes. For accurate estimation of the acceleration response, it is important to consider not only the first two lateral vibrational modes, but also higher modes. Ignoring the contribution of higher modes may lead to underestimation of the acceleration response; on the other hand, it could result in overestimation of the displacement response. Furthermore, the procedure presented in this study can help decision makers, involved in a tall building design/retrofit to choose among innovative solutions like aerodynamic mitigation, structural member size adjustment, damping enhancement, and/or materials change, with an objective to improve the resiliency and the serviceability under extreme wind actions.

Field Measurement of Wind Effects of Roof Accessory Structures on Gable-Roofed Low-Rise Building

The components and claddings of low-rise buildings are usually destroyed first during typhoon disasters in coastal areas. Roof accessory structures can change the flow pattern on the roof, thus effectively reducing the wind load on the roof surface and the damage to the low-rise buildings. Three types of aerodynamic mitigation plates, that is, (1) 0.3 m high full-length roof-edge plate, (2) 0.3 m high and 0.5 m + 0.5 m long roof-corner plate, and (3) discrete roof-edge plates with different spaces (which can be used as advertisement boards), are studied on the basis of the field measurement results under roof pitches of 10° and 18.4°. By comparing the results of the roof with and without constructed plates, it is implied that the three types of plates can affect the formation of conical vortexes and can significantly reduce the mean and fluctuating pressure coefficients in the windward corner. Compared with the constructed plate, the roof ridge has a larger influence on the wind loads on leeward roof.

Aerodynamic Mitigation of Roof and Wall Corner Suctions Using Simple Architectural Elements

This paper presents the use of simple architectural elements such as aerodynamic mitigation devices for reducing high wind-induced suctions occurring at roof and wall corners of low-rise buildings where wind-induced building envelope failures usually initiate. The architectural elements considered in the current study include trellises (pergolas), roof extensions of gable ends (gable end ribs), ridgeline extensions (ridge rib), and sideways extensions of walls (wall ribs). A small-scale model of residential villa was tested in a boundary layer wind tunnel for two different roof geometries (gable and hip). Moreover, selected cases were investigated at the Wall of Wind, a large-scale testing facility, to investigate scale effects. The effectiveness of these architectural elements in reducing high suction (negative pressure) was assessed by comparing the wind-induced pressure measurements obtained before and after introducing the elements. Based on the results obtained for the worst wind angle of attacks, the peak suction was reduced after introducing the architectural elements by 65% at gable-end corners, 60% close to roof ridges, 45% at soffits, 35% at wall corners, and 25% at eaves. These simple architectural elements, which can be retrofitted to the stock of existing homes or incorporated into the design of new buildings, can be used as aerodynamic mitigation devices for reducing peak suction at critical locations of the building envelope.

Aerodynamic interference effects and mitigation measures on vortex-induced vibrations of two adjacent cable-stayed bridges

By examining the two neighboring Haihe Bridges with semi- and full-closed bridge decks, the aerodynamic interference between the two decks on the vortex-induced vibration (VIV) and the corresponding aerodynamic mitigation measures are investigated via a series of wind tunnel tests with a spring-suspended sectional model aided with computational fluid dynamics (CFD) method. The results show that the VIV responses of both bridges can be significantly affected by the aerodynamic interference and that the extent of the influence varies with the shapes of the windward and leeward decks. The VIV amplitudes of the windward bridge are often fairly close to those of the single bridge. However, those of the leeward bridge are magnified substantially by aerodynamic interference if the same structural and aerodynamic configurations are adopted for the two bridges. Otherwise, the VIV responses are not significantly increased and may even be reduced by the aerodynamic interference if different configurations are employed for the two bridges. Furthermore, an effective combined measure of adding wind barriers and sharpening the wind fairing noses of the two box decks is presented for mitigating both the vertical and torsional VIV responses of the windward and leeward bridges.