As pioneers in wind tunnel testing we provide global engineering solutions for building design, specializing in structural loads, component cladding, and occupant comfort assessment.
The BLWTL provides decades of specialized expertise, offering clients comprehensive wind analysis for structures around the globe. We specialize in assessing the unique challenges posed by tall, super-tall, and uniquely-shaped buildings in dense urban environments.
We deliver highly accurate, wind-induced load and response estimates for your building. Our testing programs integrate the unique geometry, structural dynamics, and project-specific climatic conditions to ensure structural reliability.
Our pressure model wind tunnel testing provides localized pressure data for designing building caldding and envelopes, including external and differntial pressures. envelopes. For buildings with operable openings or partitions, we assess the transmission of dynamic external pressures into the interior space.
We develop precise proximity models to accurately capture the local wind effects. By simulating neighboring buildings and topography, we capture the crucial funneling and sheltering effects that drastically alter wind flow, ensuring your design loads are based on realistic site behaviour.
Our wind tunnel testing programs are designed to assess key wind-induced building behaviour under real-world conditions. The objectives of these test programs are to evaluate the safety, stability, and serviceability of the building.
Key facets of the BLWTL’s wind tunnel testing and subsequent analyses include:
Global and Local Wind Load Prediction: We predict precise wind loads based on the building’s geometry, structural properties, and site-specific climatic conditions. These loads, including the mean, background, and resonant forces, are generally more precise than standard design codes, minimizing design uncertainty and allowing for a more efficient and economical structure.
Dynamic Response Assessment: We measure or analytically predict the full three-dimensional, wind-induced dynamic motion of the structure, evaluating it against occupancy comfort criteria to ensure optimal performance and inhabitant well-being.
Rigid Model Testing
We use rigid model testing of force-balance or pressure integration models to measure aerodynamic wind forces directly in the wind tunnel. This data is processed using random vibration theory and modal analysis to determine the full structural response. We analytically calculate the resonant response of the building due to dynamic amplification of the buffeting response by combining measured force spectra with the structure’s dynamic properties. By integrating this with statistical wind climate models, we predict final loads and responses for various return periods. The raw aerodynamic data remains valuable for re-analysis, allowing us to quickly assess design changes in structural dynamic properties.
This approach uses a stiff, lightweight model to measure the structure’s wind-induced base shears and moments. These measurements are used to estimate the dynamic response based on the assumption of nearly linear mode shapes. The primary advantages of this approach are rapid model construction and minimal requirements beyond scaled geometry. However, this method is unsuitable for highly flexible structures or those with non-linear mode shapes, particularly if the frequency of higher modes coincide with significant wind energy.
Tower and Resulting Force-Balance Model
This state-of-the-art approach uses highly sensitive instrumentation to take simultaneous local pressure measurements at up to 1,000 points on a model. These pressures are converted into detailed load time histories and then integrated to determine overall structural loads. This process allows for the calculation of generalized forces using the measured load distribution and the structure’s mode shapes.
This approach offers superior detail as to the variation of wind loads over the building as well as the prediction of the torsional loads. Additionally, it enables estimation of cladding and envelope loads (see below). While pressure model testing is more time-consuming than force-balance testing as a result of the added complexity, it is often more cost-effective overall due to the above benefits.
Building and Resulting Pressure Model
Aeroelastic Model Testing
For unique, slender, flexible, or super-tall buildings particularly vulnerable to large wind-incuded responses, aeroelastic model testing offers the most accurate method for determining structural response to wind.
Aeroelastic models are meticulously designed to match the scaled geometry, mass, and stiffness properties of the full-scale structure. The model is then tested in site-specific conditions in the wind tunnel to directly measure the wind-induced responses (deflections, accelerations, bending moments). These measured responses inherently include all aerodynamic effects.
Aeroelastic Tower Model and Internal Aluminum Spine
Cladding and Component Loads
The measurements from a pressure model of a building provide the distributed wind loads required to determine the external and differential pressures necessary for cladding design. Differential pressures on exposed elements such as canopies are calculated directly, while those on cladding are calculated by estimating internal pressures.
Critical loads occur at building corners where high positive external pressure can leak through an opening (such as an operable or broken window), generating positive internal pressure that significantly amplifies the external suction on the adjacent wall. The full complexity of internal pressure from operable windows or breakage scenarios must be assessed on a case-by-case basis, considering opening size, building volume, and internal partitioning.
Local Pressure Distributions on a Building
We assess the project site climate, considering local topography and historical wind measurements. We provide appropriate wind conditions for evaluation of the bridge.
We analyze the flow patterns and speeds at ground level in urban environments to ensure that outdoor spaces meet acceptable safety and comfort criteria for pedestrians.
Connect with the Boundary Layer Wind Tunnel Laboratory to discuss your building’s unique design and challenges.