Norwegian Public Roads Administration initiated a full-scale measurement campaign on Gjemnessund Suspension Bridge to support the ferry free E39 project and development of the E39 coastal highway route in Norway. The main objectives of the measurement campaign were to increase understanding of wind tunnel tests and calculation procedures for prediction of full-scale wind actions on long-span bridges. A monitoring system was developed to measure wind flow properties, wind-induced surface pressures around the bridge deck, and bridge deck acceleration response. Alongside the full-scale measurement campaign, a scale 1:40 section model of Gjemnessund Bridge was tested in the wind tunnel of SOH Wind Engineering LLC, resembling the pressure tap locations in full scale. The dynamic and static Strouhal numbers, vortex-shedding response, and static load coefficients for a range of Reynolds numbers spanning from approx. 10^3 to 10^5 in model scale and beyond 10^6 in full scale are paid attention to. These results may be used for discussion and evaluation of common procedures to perform wind tunnel tests on streamlined bridge decks.

The final draft of the Eurocode revision for wind actions on structures contains two models for predicting acrosswind loads on tall buildings. The two models are presented and their behavior for variations of central parameters is investigated focusing on the parts of the parameter space where their applications border each other. It is found that the models provide very different predictions for the across-wind loads at these intersections. Across-wind loads are then investigated through wind tunnel tests carried out by Svend Ole Hansen ApS applying both the High-Frequency Base Balance (HFBB) and the High-Frequency Pressure Integration (HFPI) techniques. Finally, key results of the wind tunnel tests are compared with the Eurocode draft predictions and deviations are discussed.

The ability to reproduce aeroelastic loads of horizontal-axis wind turbine blade cross sections by Theodorsen function, currently employed by researchers and practitioners, is investigated. Section model experiments are conducted on two reduced-scale models of airfoil sections, derived from a benchmark large-scale wind turbine blade. Uncertainties associated with aeroelastic properties of the wind turbine blade sections, measured in the wind tunnel, are also examined. Uncertainties are associated with random, experimental laboratory errors. Statistical inference is utilized to characterize experimental errors. The results suggest that the Theodorsen function cannot be used while empirical aeroelastic coefficients (Scanlan derivatives), dependent on the cross-section geometry, are necessary. Furthermore, experimental errors, aptly quantified in this study, should be incorporated and included in reliability analyses of wind turbine blades.

A pressure field on a stationary bridge section with a clear signature from vortex shedding is obtained from a numerical simulation. The pressure field is subjected to modal decomposition using the snapshot prober orthogonal decomposition method (POD), the exact dynamic mode decomposition method (DMD) and a novel application of the eigenvalue realization algorithm (ERA) where the correlation functions of the pressure field is used as Markov parameters. All three methods are able to identify spatial mode shapes of the surface pressure field due to vortex shedding. The Strouhal number is estimated using dynamic mode decomposition and the eigenvalue realization algorithm where the latter is the most accurate and precise method. Finally, the ERA is applied to estimate Strouhal numbers and vortex shedding pressure mode shapes under different flow conditions in wind tunnel and full-scale testing of the Gjemnessund bridge in Norway.

Codified specifications on wind actions, such as those prescribed in the Eurocode EN 1991-1-4, ISO, and ASCE norms, contain various procedures for calculating the buffeting response of typical buildings and bridge structures. Most often such procedures provide a simple, robust, and operational framework allowing for accurate predictions of the relevant wind loads and responses for many types of structures. The codified procedures for calculating the buffeting response are, however, not always applicable in the case of complex loading scenarios, such as the resonant response of structures with mode shapes of non-constant sign, and some of the prescribed mathematical expressions may contain coefficients and variables that are difficult to interpret in a physically consistent manner. The present document outlines a new codified procedure for calculating the along-wind buffeting response of buildings and bridges. The new procedure is simple and operational, and extends the current Eurocode EN 1991-1-4 provisions to cover mode shapes with non-constant signs, allows for the systematic use of cross-sectional admittance functions, and ensures an asymptotically consistent modeling of the two-dimensional surface pressure characteristics. The perspective of the new calculation procedure is also discussed to reflect on the implications of updating the buffeting response calculation procedure in the next revision of the Eurocode.

The problem of aerodynamic flutter has received much attention and continues to be important for slender structures, such as long-span suspension bridges. The wind flow across the structure can approximately be described as a two-dimensional flow across a moving flat plate, and the bridge motion can be expanded in heave and pitch motions, leading to the traditional aerodynamic derivatives description. In this paper, the classical Theodorsen model [NACA report no. 496, 1934] is revisited, and an extended method is proposed, allowing computation of the aerodynamic derivatives for more complex planar geometries, such as tandem configuration multi-deck bridges. In keeping with the Theodorsen model, the vorticity in the wake is modelled as a vortex sheet advected passively with the free-stream velocity. The bridge deck influence on the wind flow is described by a number of point vortices, and the aerodynamic forces and moments on the bridge are obtained as the rate-of-change of their aerodynamic impulse and angular impulse. Twin-deck bridges are considered for a number of inter-deck spacings. A set of critical reduced wind speeds, depending on the spacing between decks, are identified. Preliminary wind tunnel test results are reported and shown to correspond well to the point vortex model predictions.

The technology development within the structural design of long-span bridges in Norwegian fjords has created a need for reformulating the calculation format and the physical quantities used to describe the properties of wind and the associated wind-induced effects on bridge decks. Parts of a new probabilistic format describing the incoming, undisturbed wind is presented. It is expected that a fixed probabilistic format will facilitate a more physically consistent and precise description of the wind conditions, which in turn increase the accuracy and considerably reduce uncertainties in wind load assessments. Because the format is probabilistic, a quantification of the level of safety and uncertainty in predicted wind loads is readily accessible. A simple buffeting response calculation demonstrates the use of probabilistic wind data in the assessment of wind loads and responses. Furthermore, vortex-induced fatigue damage is discussed in relation to probabilistic wind turbulence data and response measurements from wind tunnel tests.