Consulting Services in Wind Engineering

Environmental Testing
Many structures have the potential to create unpleasant, or even dangerous, wind conditions at ground level. Fortunately, these effects can be investigated and remedied at the design stage through wind tunnel model testing.

Environmental testing involves the construction a suitably scaled model of the building and the surrounding area, which is then tested in the wind tunnel with hot-wire anemometers. The results of the testing and compared to local wind acceptance criteria. If an environmental wind problem is encountered, a variety of solutions can be investigated in consultation with the designers. Environmental conditions are often required for Council approval. Velocity measurements can also be used for the design of mechanical discharge locations.

Cladding Pressures
In order to design cladding systems for high-rise and medium-rise buildings, it is important to have a reliable prediction of the external wind pressures acting on the building surface. Due to the inherent conservatism in building codes, design wind pressures from a wind tunnel test are generally significantly lower than those calculated from building codes. Wind Engineering Services uses a simultaneous pressure measurement system, which allows differential pressures on thin architectural elements to be measured.

The wind pressure distribution as predicted by wind tunnel test results may also be used for structural design, e.g. in evaluating bay loads on long-spanning structural members. Insurance costs can be considerably lower for buildings that have been wind tunnel tested.

The appropriate scaled model of the development is fitted with between two hundred and one thousand pressure taps distributed over the surface of the building. Maximum design pressures for the appropriate return period are produced for the structure.

Structural Pressures
For larger buildings, such as large roofed structures, a structural pressure test may be appropriate for the design of the primary members. A suitably scaled model is pressure tapped and simultaneous panel pressures are measured over the structure. Combining these pressures with structural information allows an estimate of peak responses in any member, and a design effective pressure distribution across the structure.

Dynamic Testing
On-site building response measurements have shown that strong winds acting on modern tall buildings and structures can cause significant loads and vibrations. Recent trends toward slender, flexible, and light-weight buildings have left a large number of buildings susceptible to wind-induced motion, and human perception of building motion has become a critical consideration in modern building design. More complex building shapes and structural systems further accentuate eccentricities between the mass centre, the elastic centre and the instantaneous point of application of aerodynamic loads and generate significant torsional effects. Again the natural conservatism in design codes means that a significant reduction in the predicted overturning moments, and accelerations can be realized.

Aeroelastic
Aeroelastic model test rigs have been developed to measure wind-induced translational and torsional loads and vibrations. The model design and construction requirements are modest and consequently there are both time and economic advantages. The mass moment of inertia, stiffness, damping and even the geometric properties of the building models can be readily changed and the aeroelastic effects easily identified. The effectiveness of different damping systems such as tuned mass dampers (TMD) to control dynamic motions of buildings can also be readily demonstrated.

High-Frequency Force Balance
As with the aeroelastic test this yields a measure of the overturning moments and accelerations at the top of a tall structure. Unlike the aeroelastic test where the flexibility, mass, and damping of the full-scale structure are modelled, the force balance test directly measures the dynamic forces and moments and uses these to calculate the dynamic response of the structure. For general high-rise design this technique is more appropriate. The modelling for this test is far simpler than the aeroelastic test, and all dynamic characteristics are included at the analysis stage. Thus, the dynamic information is not required at the outset, and if the dynamic characteristics change during the period of the project, these can easily be incorporated into the analysis, whereas the aeroelastic test would require a revised model to be constructed.

Full Scale Testing Wind Speed And Wind Induced Building Response
A full-range of short- or long-term wind monitoring and wind induced building response measurements is available, including wind speed and direction, internal and external pressures, and building accelerations.

Structural Dynamics
To verify the dynamic structural analysis, Wind Engineering Services have pioneered direct dynamic measurement techniques of structures to determine the natural frequencies, damping characteristics, and mode shapes. These techniques include crane excitation, and synchronised human movement. With no wind conditions, these simple non-intrusive techniques can be completed in under a day. These techniques have been used successfully on over 40 structures in Australia and overseas.

Snow Drift Modelling
Snowdrift modelling is used to predict the deposition pattern behind structures that will be experience wind driven snow. The output from this test is a prediction of the rate of snow deposition. This information is used at the design stage to align buildings with respect to the prevailing wind direction, and to design entranceways to ensure that they remain accessible.