Advanced and Robust Analysis of Wind Effects
Advanced and Robust Analysis of Wind Effects
150 The Donway West and 4 Overland Drive, located in the Don Mills area of North York, is a perfect example of the intensification necessary to meet the increased housing demand resulting from high population inflow to the Greater Toronto Area (GTA) and the unaffordability of homeownership in Ontario. Akelius plans to build up the existing two-building site by adding two new residential market-rate rental buildings, as shown in Figure 1 below.
Diamond and Schmitt designed the two new mid-rise buildings to complement the existing structures by incorporating a brick similar to that used in the existing rental buildings. They then enhanced the façade with glass and white metallic features while maintaining the boxy shape to integrate old and new aesthetics fully. The project also involves the addition of two underground parking levels and a central courtyard, so not only would this project target the undersupplied rental market while providing transit accessibility, but it would also improve the ground level and below-grade conditions of the existing site with soft and hard landscaping.
Windtech was pleased to provide the pedestrian wind environment study for the site as a part of the requirements set forth by the City of Toronto for site plan approval. Ellen Marejka, an Associate Director of Windtech’s Toronto Office remarks, “As you can imagine, wind contributes to human comfort and can impact everyday activities whether it be waiting at a bus stop or sitting on a park bench. The wind comfort, and even thermal comfort, of outdoor public spaces, is crucial to the functionality of the overall design. A pedestrian-level wind study strives to address any of these wind concerns at the site before any groundbreaking or actual construction occurs. This is done by ensuring the wind conditions on and around the site are within acceptable comfort criteria throughout all seasons”.
But what triggers the need for a pedestrian wind study?
Toronto classifies the need based on the location of the development and the height of the building. Generally speaking, the taller the building, the greater the need. The City accepts two types of wind studies: wind tunnel studies (which was the approach in this project) or computational fluid dynamics modelling (which Windtech also offers).
With the help of the architect and developer, Windtech created a digital model of the study buildings and the “proximity model” or “surrounds” (both terms are used to describe the surrounding environment, shown in grey in the figure below).
Once the digital model was created, a physical model was fabricated out of foam using computer-aided manufacturing. Pressure sensors were installed at the ground-level locations, and each location was classified based on Table 1 below. The model was placed on a turntable in one of our four wind tunnels and tested at the prescribed number of wind directions. There were two testing scenarios completed: the existing site conditions without the proposed development and the site conditions with the proposed development.
The results of the wind tunnel study were compared to the comfort criteria in Table 1. For the most part, the results were within acceptable limits. However, where the comfort criteria were exceeded, and a location was deemed too windy, Windtech proposed mitigation measures to alleviate the wind effects. This includes a 3m awning to span the south and western corners of the 150 The Donway West building and densely foliating evergreen landscaping features in the courtyard region. These mitigation features would reduce the wind to an acceptable level while having the least possible impact on the architectural design or aesthetic features.
There is a growing need for more purpose-built rental developments in the GTA like the one proposed by Akelius. As mentioned by Shaun Hildebrand from Urbanation: “The GTA rental market remained substantially undersupplied during the first quarter of 2023. Even though supply is set to increase in the near-term, it is expected to be short-lived and insufficient to offset demand.” While this two-building development proposes the addition of much needed 242 rental units, there are bigger plans to develop and intensify the Don Mills area to meet population demands. Currently, there are ten development applications within a 1-kilometre radius as shown in Figure 4.
Windtech is happy to announce that we have opened an office in Toronto to serve our clients in the GTA better. We offer wind environment studies wind tunnel studies (like this one), or CFD studies for new developments in accordance with the city requirements. This type of wind study is required for site plan approval in most urban municipalities in southwestern Ontario.
If you are working on any projects that could benefit from the capabilities presented in this article, please reach out to our regional offices Sydney & Melbourne, Australia, London, UK, and Mumbai, India. New York & Miami, USA, Toronto, Canada, Dubai, Hong Kong & Singapore, we guarantee to support you wherever you are based.
To get regular updates on news and events, please follow us on our LinkedIn page.
Regardless of your role in the professional sphere, mastering certain soft skills is essential, with problem solving topping the list. Not everyone is an innate problem solver, and this skill is increasingly crucial in our complex, fast-paced world.
What exactly do we mean by ‘problem solving’? It’s the ability to identify, understand, and effectively address issues, whether they impact your entire organization or just your personal work experience. Remember, from minor hiccups to major organizational challenges, each problem presents an opportunity for growth and innovation. And for those times when you don’t know how to do your academic work, remember that services like Write My Papers are there to support you, offering expert assistance for your paper-writing-related problems.
Here are five effective strategies to sharpen your problem-solving skills, viewing issues through a solution-oriented lens:
Implementing the solution is just the beginning. Monitor its effectiveness, be ready to make adjustments, and remember that problem-solving is a skill honed over time.
What are the 5 steps of effective problem solving?
The steps include identifying and understanding the problem, researching its background, visualizing it, brainstorming solutions, and choosing the best one.
How important are problem-solving skills in the workplace?
Problem-solving skills are crucial in the workplace. They enable employees to efficiently tackle challenges, innovate solutions, and contribute significantly to organizational goals. These skills enhance adaptability, creativity, and teamwork, making them vital for career progression and organizational success.
How to develop a problem-solving mindset?
Practice, patience, and openness to learning from each experience are key. Use the outlined steps and collaborate with your team for enhanced outcomes.
Can problem-solving skills be learned or are they innate?
Problem-solving skills can definitely be learned and improved over time. While some individuals may have a natural inclination towards effective problem-solving, these skills can be developed through practice, exposure to different scenarios, and learning from both successes and failures.
This guide is designed to assist you in growing your problem-solving skills. Whether you’re facing challenges at work or in your daily life, these techniques will prepare you to face them head-on.
The Surat Diamond Bourse is a remarkable structure that redefines architectural possibilities and a symbol of contemporary architecture and engineering. Emerging as the world’s largest office building, surpassing even the Pentagon in size, this remarkable structure redefines architectural boundaries. Comprising a sequence of nine interconnected rectangular modules that radiate from a central “spine,” this sprawling 15-story complex occupies over 35 acres. Notably, its distinctive design is highlighted by a substantial standalone blade wall, a key architectural element.
Windtech’s specialized wind engineering services played a pivotal role in safeguarding the structural integrity of this innovative masterpiece, with unique analysis required to determine the wind actions on the blade walls. Aaron Lefcovitch, a Director of Windtech, indicated that “The blade walls are not too dissimilar to stadium roofs or large canopies in that they fall into the same category of structures known as Long-span structures. Long-span Structures are inherently sensitive to the forces of wind due to the extent of the area exposed to the wind, relative light weight, and low stiffness. Unlike tall buildings, it becomes exceedingly more difficult to determine the loads on these structures using a code-based approach, especially when the natural frequency of the structure is lower than 0.8Hz.
There have been numerous cases (e.g., WIN Stadium in Wollongong), where code-based design was unable to predict the critical asymmetric load cases that are dictated by a structure’s unique support system, resulting in design loads that do not reflect reality. The implication is a structural design that may not be adequate to resist the actual wind loads or is significantly over designed, affecting the aesthetics of the design or adding unwanted cost to the project during construction.”
The long-span walls of the wind tunnel model were fitted with a total of 183 pressure sensors, divided into 83 panels as indicated in Figure 3. Several pressure sensors were assigned to each panel, and the time-series of the results from each pressure sensor, which are acquired simultaneously for all pressure sensors, are area-weighted to determine the average net pressure acting on each panel.
Critical load cases were suggested in this study to account for the various wind load combinations acting on the long-span wall structures. Once the various critical load cases were determined, these were applied by the structural engineer to the FEA model of the long-span wall structures, allowing them to adequately design the member sizes and lateral stiffeners that were used to make up the structural design.
Tony Rofail, Managing Director of Windtech, indicated that “There are many ways to determine wind loads on long-span structures depending on the client’s requirements. The simple area-averaging technique, as was used on the Surat Diamond Bourse project, is the simplest method. However, if the client is keen to optimize the structural design, we can offer the Load Response Correlation (LRC) method, also referred to as the Load Effect method. This method produces unique panel load case combinations linked to a set of different types of maximum and minimum Load Effects spread across the structure such as the the reaction force at a node, stress in a beam, deflection of a node, or any Load Effect that the structural engineer sees as being critical to the design of the structural system. It is more computationally intensive, but not subject to the same conservative assumptions seen in simpler techniques. We see it commonly used when clients wish to pursue more pure forms of performance-based design to reduce project costs, or when there is a requirement to minimise the structural member sizing from a design aesthetics point of view. The Load Effect method also allows us to account for resonant response effects, which is important when the natural frequency of the structure falls below 0.8Hz.
This project is a shining example of Windtech’s commitment to pushing the boundaries of wind engineering innovation and delivering solutions that shape the future of modern architecture.
If you are working on any projects that could benefit from the capabilities presented in this article, please reach out to our regional offices Sydney & Melbourne, Australia, London, UK, and Mumbai, India. New York & Miami, USA, Dubai, Hong Kong & Singapore, we guarantee to support you wherever you are based.
To get regular updates on news and events, please follow us on our LinkedIn page.
Imagine you are on the couch, watching your television, and suddenly the balcony door and adjacent façade behind you start banging loudly and then soon after the television starts to wobble and the internal partitions start vibrating. This is what it is like to experience the Helmholtz effect. You may be surprised to hear that occurrence of this phenomenon is increasing
This starts with the configuration of the balcony space adjacent to the façade. More specifically if it is a wintergarden with one single fixed opening, which would configure the balcony in the same way as an organ pipe or whistle. The same effect can sometimes be experienced to a lesser degree if one is in a moving car with one window partially open.
So far, we have only seen this effect occur where the balcony is configured as a wintergarden and incorporates a fixed opening that is configured as a 3-sided orifice (i.e. a fixed balustrade below that connects to the floor and full-height side panels or walls that extend out from either side, in-line with the aspect of the fixed opening).
As the wind moves across or into the opening (this effect does not tend to occur when the opening is in the lee of the building, relative to the wind direction), the external pressure fluctuations tend to become organised into a narrowband pulsating frequency. It is possible to calculate that frequency and often it will tend to be very close to the natural frequency of a glass panel or mullion. The close frequencies would set off a tuning fork effect that results in significantly increased amplitude of oscillation of the façade to the point where it could in some cases engage the floor slab which in turn would start shaking the furniture (including the television!) and internal walls.
The simple solution is to avoid wintergardens. If you must have a wintergarden then you should consider at least to provide louvres in the fixed opening, although this is not an ideal solution as it only solves this problem when the louvres are shut, and some planning authorities will count the balcony as part of the indoor floor area in that case.
Some of the solutions that we have proposed in the past include the following:
Windtech offers a preliminary assessment of this effect as part of their comprehensive desktop wind noise assessment for new developments. This wind study is highly recommended, especially for residential developments.
If you need assistance with a Helmholtz Resonance effect in your project, please reach out to our dedicated wind engineers at our regional offices in Sydney & Melbourne, Australia, London, UK, and Mumbai, India. New York & Miami, USA, Toronto, Canada, Dubai, Hong Kong & Singapore, we guarantee to support you wherever you are based.
To get regular updates on news and events, please follow us on our LinkedIn page.
Buildings of different heights and shapes require different approaches when it comes to selecting the appropriate technique used for wind tunnel testing to determine the wind actions on the structure. When we need to bake a cake and we do not use a frying pan and we do not use an oven to make scrambled eggs. This issue is no different. This article provides some key tips when specifying scope for a wind tunnel study to determine the structural loads on a large building.
A “tall” building is generally one where the motion of the building in the wind can significantly influence the total peak load. In technical jargon, we refer to such a building as having a significant resonant dynamic response. Such buildings are typically greater than 15 storeys (45m/150ft) in height. For tall buildings, we tend to assess the dynamic wind actions on the structure, including the effect of the dynamic properties of the structure itself on these dynamic loads.
The outputs of such a study consist of the following:
For the vast majority of tall buildings, either a rigid aerodynamic model is used in the wind tunnel – using either a High-Frequency Force Balance or a Pressure Integration method. At Windtech, we use both methods, but as we also have a high-quality pressure measurement system with minimal phase lag, high sampling rates, etc., the latter approach is better as it enables us to more accurately determine the vertical distribution of the load cases.
So, what happens if a building is less than 15 storeys in height? Firstly, in most cases, the wind loads do not govern unless it is in a cyclonic region that is also not subject to very high seismic loads. From our experience, buildings close to 15 storeys in height located in cyclonic regions have benefited from a wind tunnel study in significantly reducing the design wind loads and with significant impacts on the bottom line in terms of construction costs. The issue with buildings that are 15 levels or less in height, particularly those with a large footprint or a complex form, is that the horizontal distribution of the wind loads is often more important than the vertical. For these, it would be far more helpful to present the resulting design load cases in the form of surface panel pressures or externally applied point loads.
In contrast, some buildings are so tall or slender that their own deflection/movement can either reduce or increase the peak dynamic response. This phenomenon is referred to as aerodynamic damping. For these, we recommend an aeroelastic model study, which is the only way we can reliably determine the above phenomenon for each different angle of attack. The Quality Assurance Manual for Wind Engineering, first published by the Australasian Wind Engineering Society (AWES) in 2000 and recently updated in 2019, provides some guidance on when this effect becomes significant and for which building plan shapes. For these buildings, it is important to use a dynamic model in the wind tunnel that accurately represents the relative stiffness of the sway modes, the structural damping, mass density, and distribution, and is tested at the same reduced velocity as the full-scale building. This technique is referred to as an aeroelastic model study.
Windtech director, Tony Rofail, a key author of the AWES Quality Assurance Manual for Wind Engineering, says, “Some very tall rectangular plan buildings can significantly benefit from an aeroelastic model study as they generally tend to bring down the peak response – however, it would be dangerous not to do so for other shapes where the loads can easily go the other way.”
In 2007, Tony Rofail published a method on how we can determine the effect of a structural linkage between tall buildings at high elevation (more than 20% of the height of the taller of the 2 buildings). This method enables the development of a rationalised set of critical load cases rather than the earlier practice of going blind and providing hundreds of load cases to the structural consultant. A rigid linkage can have a significant effect on the response of the two linked sub-structures, and the taller/more dynamic the structure, the more significant the effect.
If you are working on any projects that could benefit from the capabilities presented in this article, please reach out to our regional office via our Contact Us page.
To get regular updates on news and events, please follow us on our LinkedIn page.
