This paper providesNon-synoptic wind succinct insights into research and practice concerning non-synoptic wind effects on buildings, with a specific focus on recent advancements in the study of tornadoesTornado and downburstsDownbursts. Based on recent research on non-synoptic windsNon-synoptic wind, experimental techniques and models were developed to examine their effects on buildings and structures. These developments have prompted initial efforts toward establishing design provisions in wind standards and codesWind standards and codes of practice. The paper sheds light on some key aspects related to: (1) laboratory modeling techniques used to replicate non-synoptic windNon-synoptic wind fields and derive design pressure coefficientsPressure coefficients; (2) findings from previous experimental studies assessing wind loadsWind loads on low-rise buildings; and (3) development of provisions in current wind codes/standards. Evidently, despite notable developments, the provisions in existing wind codes and standards remain limited to address such challenging environmental conditions with a need for continued research and codificationCodification efforts.

This paper extends the knowledge and methodologies in structural Computational Wind Engineering (CWE) applications in urban environments. A newly developed inflow turbulence generation technique is utilized that combines efficiency and accuracy in LES modeling - the so-called Dynamic Terrain (LES-DT). Main aspects of inflow turbulence generation for LES are discussed, and the differences between state-of-the-art techniques and the LES-DT are put into perspective. LES-DT is an engineering-based method, and it is applied for isolated and urban configurations, while the accuracy of the local wind induced peak pressures on the entire building envelope is evaluated, based on experiments from TPU for perpendicular and oblique wind. The impact of energy fluctuations of high frequency content on the incident flow and to mean and peak wind-induced pressures is discussed. LES-DT provides control over these fluctuations and can lead to accurate results via an efficient framework. Conclusions are drawn on sheltering effects for buildings in neighbors' wakes, with LES-DT accurately capturing complex interference effects through validation metrics. An open-source code is available to facilitate its usage (https://github.com/tpotsis/DTv1.0). Given the current efforts to codify the use of CWE for structural applications internationally, this paper offers experimental and numerical insights to support this direction.

Wind loadsWind loads on buildings with non-rectangular plans were investigated through limited experimental and Computational Fluid Dynamics (CFDComputational Fluid Dynamics (CFD)) studies. Therefore, the wind design of non-rectangular buildingsNon-rectangular buildings is described through short guidance in the current building codes and standards. This paper predicts wind loadsWind loads on roofs and walls of non-rectangular buildingsNon-rectangular buildings using Ensemble Machine LearningMachine learning (EML) technique. The EML combines predictions of several regressors, such as Gradient Boosting (GB) and Random Forest (RF), and results in predictions more accurate than the outputs of a single regressor. Numerous tests were performed at the wind tunnelWind tunnel for building models with plan shapes of L, U, T, and X to create a datasetDataset for machine learningMachine learning (ML). An exhaustive grid search with K-fold cross-validationValidation was used for hyperparameters optimization. The Ensemble Machine LearningMachine learning models predicted wind pressure coefficientsPressure coefficients with minimal Mean Squared Error (MSE) and coefficients of determination (R-squared) of up to 0.97.

The accelerating pace of global urbanization rises the concerns regarding wind environment issues of highdensity building complexes. Urban wind environment is critically influenced by the upstream exposure range, yet quantitative recommendations or its selection-particularly for pedestrian-level wind (PLW) assessment-remain limited for high-density urban morphologies. This study bridges this gap by investigating the optimal upstream fetch length for urban environmental through CFD simulations of a high-density area in Kowloon, Hong Kong. Employing the SST k-omega turbulence model, four upstream fetch distances (250 m, 500 m, 750 m, and 1000 m) were evaluated for their impact on PLW conditions and wind profiles. Rigorous validation via wind tunnel experiments confirmed the reliability of the CFD approach. The results show that the required upstream fetch length for PLW stability is 750 m when the approaching wind direction is aligned with the main street and 500 m when not aligned. Additionally, highly rough and heterogeneous upstream buildings accelerate the stabilization of lower wind profiles. The upstream fetch length required for stability of mean wind velocity profiles ranges from 750 m to 1000 m. The numerical results also indicate that the required upstream fetch depends on the exposure types and upstream building configuration. For the present high-density, high-rise urban morphology, rough and heterogeneous upstream buildings tend to accelerate the convergence of vertical mean velocity profiles, while the horizontal distribution of pedestrian-level wind may still require a longer fetch to become insensitive to further upstream extensions. The mechanism of the difference is discussed.

Wind effects on buildings with rectangular plans have been investigated widely by wind engineering researchers either in wind tunnels or through CFD simulations. These studies provided comprehensive overviews and detailed descriptions of wind pressures on rectangular buildings and created the basic source required to formulate the wind provisions in the national and international codes and standards. However, buildings with irregular (i.e., non-rectangular) plans have not received adequate attention from wind tunnel investigations. Therefore, wind loads on irregular buildings are described shortly and shyly, if at all, in the current building codes and standards. This paper describes the experimental investigations into the flat-roof pressures of buildings with four non-rectangular shapes -L, U, T, and X- in an atmospheric boundary layer wind tunnel. The results reveal that the distribution of wind loads on the outer roof corners and edges of buildings with non-rectangular plans resembles that experienced by a rectangular building. However, the wind loads on the inner perimeter area, particularly the inner edge of the Ushaped building, were observed to be generally higher than those recorded on the edges of a typical rectangular roof. Furthermore, the wind tunnel measurements not only provided valuable data but also served as a dataset when applying Machine Learning (ML) as a tool to predict wind loads on irregular buildings. This involved the utilization of a Gradient Boosting Regressor (GBR) and Artificial Neural Networks (ANN), using two data split approaches: random and structured splits. The ML models exhibit significant predictive accuracy, achieving minimal Mean Squared Error (MSE) and coefficients of determination (R-squared) of about 0.97 for wind pressure coefficients. Further, the study demonstrated that a structured split of the dataset reflects a more realistic assessment of the ML models.

This paper presents the seismic response of a 4-storey office building subjected to uniaxial and biaxial seismic excitations. The building located in Montreal, QC, has a square floor plan and the steel braced frames are displaced in two distinct configurations that lead to a regular and an irregular (torsionally sensitive) building. As per the code requirements, the former and the latter are designed for 5

The paper provides the trajectory of research and practical applications established in structural wind engineering during the last decades in Canada, for low-mid-rise buildings. Various perspectives are discussed such as code provisions, wind tunnel experiments, full-scale measurements, while emphasis is given to Computational Wind Engineering (CWE). Latest versions of the National Building Code of Canada (NBCC) are considered, and some important new additions are discussed. Wind tunnel experimental results are presented from various studies to indicate the level of agreement among various facilities. The complexity of the interaction between wind flow and structures in the atmospheric boundary layer is significant, considering the differences found among similar experimental campaigns. Full-scale measurements are also compared with wind tunnel results and code provisions. Thresholds of accuracy based on various building configurations for area averaged and local loads are drawn that are useful for validation of computational approaches. CWE has rapidly evolved during the last decades and some representative studies from the literature and their methodologies are discussed. National and international codes/standards committees have initiated efforts to establish guidelines for practical use of CWE for estimation of wind-induced loads, on their upcoming versions. The endeavors from Eurocode and the Architectural Institute of Japan are analyzed. A novel state-of-the-art application is presented that has recently been developed by the authors, with good prospects to combine accuracy and efficiency for CWE. Results are within the threshold of accuracy established by comparisons between various wind tunnels, fullscale data and code provisions.

Incremental Dynamic Analysis is a powerful tool for the performance assessment of structures where a full range of responses can be mapped. Currently, an open discussion among researchers is the scaling of wind loads at increasing hazard intensities. In common practice, local aerodynamic pressure data from wind tunnel testing are normalized with respect to the mean wind velocity. Then, the value is linearly scaled up to provide wind loads at considered limit states. The main issue in the linear scaling of winds is the non-consideration of cross-correlation between different time histories and the mean wind velocity. To address this issue, the Wieringa gust model is applied to account for the dependency of gustiness on mean wind speed, thereby updating the scaling coefficients for both mean and turbulent wind components. This methodology is demonstrated through the application of wind IDA on a high-rise steel hospital in Montreal, Canada. The building is designed to meet the code requirements for wind and earthquake loads. Finite element models that incorporate geometrical and material nonlinearities of building's lateral force-resisting systems are developed in OpenSees. These nonlinear models are used to analyze the impact of linear gust scaling on the building's performance under varying wind intensities.

Wind-Driven Rain (WDR) is a main source of moisture impacting building facade, which can negatively influence their hygrothermal performance and long-term durability. The WDR deposition patterns on building facades vary significantly based on different meteorological and geometrical parameters. Among the three main approaches for studying WDR on buildings (experimental, numerical, and semi-empirical), the ISO semi-empirical method is widely used despite being subject to substantial errors under certain situations (2-4 times overpredictions). A major source of these errors is the suggested constant Wall Factor, which is limited to six primary building configurations by ISO semi-empirical model. This study aims to improve the ISO semi-empirical model by generating refined Wall Factors for any flat roof stand-alone building configurations using ML approach through three main steps. Part A, using Computational Fluid Dynamics (CFD) to quantify WDR loading for various meteorological and geometrical parameters and generate a comprehensive dataset. The steady-state standard k-omega RANS turbulence model is coupled with Eulerian Multiphase (EM) WDR techniques (referred to as RANS-EM) to simulate WDR. This approach has been validated with existing wind-tunnel and field measurement data. Part B uses the CFD-generated Wall Factor dataset to train various Machine Learning (ML) models (i.e., Decision Trees Regression (DTR),), and Deep Learning (DL) model (i.e., Artificial Neural Network (ANN)), aiming to generate refined Wall Factors applicable across a broad range of parameters. Part C compares the WDR estimation using the ISO Wall Factor and the refined Wall Factor against field measurement results, demonstrating an average error reduction of 53 %.

Buildings with rectangular plans were, in the past 50 years, the main focus in the wind engineering field. Consequently, the wind design provisions of rectangular buildings are well-established in the wind codes and standards. On the other hand, wind design provisions for nonrectangular buildings are generally not available in wind codes and standards. This paper investigates wind pressures on roofs of noncurved and nonrectangular buildings with four shapes, L, U, T, and X, with different plan dimensions and heights. The experimental results were analyzed and compared with the design provisions and guidelines of National Building Code of Canada and the American standard for rectangular buildings. It was found that the wind loads on the inner edges and corners are higher than those on the outer edges and corners of nonrectangular buildings. In addition, the comparison with NBCC indicated that design provisions are comparable to the experimental results in the corner zone and lower than the experimental peaks in the edge and interior zones. The experimental results also indicated that the size of the roof pressure zone is mainly dependent on the roof height. Furthermore, the comparison with the American standard showed that the standard design provisions are conservative.

Very limited studies have been carried out on wind loading on attached canopies. Current versions of the Canadian code and the American standard provide a procedure for calculating the wind loading on attached canopies. These provisions include a chart to find out both upward and downward wind pressures on the attached canopy. Most past and recent studies regarding this topic have been confined to low-rise buildings. Also, the effect of canopy width has not been investigated thoroughly. Thus, structural engineers are asking for guidance in the estimation of wind loads that may act on canopies in tall buildings. This paper presents a study on the effect of wind loading on attached canopies in medium-height and tall buildings. In this study, high-rise (37 m) buildings with canopies attached to the wall at different heights were tested. In addition, canopies with different widths were also tested. The test program, which was carried out in the Wind Tunnel Laboratory of Concordia University, Montreal, shows that canopies attached at the top of a tall building may experience 70% more suction than that of a low-rise building. In addition, this paper also presents the effect of building height, canopy height, wind angle of attack and effect of considered effective area on wind loading on canopies, which will help structural engineers better understand the behavior of canopies under wind loads both in low-rise and taller buildings. Design provisions for appropriate wind forces for canopies in taller buildings are also provided to help structural engineers.

Computational Wind Engineering is expanding rapidly in the last decade and is expected to be introduced as a design tool for wind-induced loads in future code provisions and standards worldwide. The paper discusses the current CWE shortcomings of the state-of-the-art and proposes a methodology that targets to close the current research gaps, from a practical point of view. Monitoring wind tunnel experiments, significant deviations of instantaneous velocity profiles due to high turbulence intensity are expected to be critical for design pressures. This inspired the novel modeling technique - named Dynamic Terrain - that reformulates the turbulence characteristics and assumes that each instantaneous profile is produced by changing the corresponding terrain conditions. Successively derived profiles from the wind tunnel are introduced as inlet conditions in coarse LES computational domain and propagate inside the domain to interact with the building. The incident flow is successfully modelled, in terms of mean, turbulence intensity and spectral content. Mean, standard deviations and peak pressure coefficients correlate well with experimental results and the procedure is advantageous compared to similar computational techniques. The target accuracy is achieved, benefits and limitations of the method are discussed, and conclusions based on experimental and computational observations are drawn.

Computational fluid dynamics (CFD) has been developing rapidly during the last decades for usage in wind engineering. OpenFOAM plays a big role in this respect since it is a reliable open-source tool frequently used in state-of-the-art applications. In the present research study, the focus is given to the analysis of wind flow, mean, and fluctuating properties of two environmental cases using a novel inflow generator method for Large-eddy simulation (LES) in OpenFOAM. This refers to the dynamic terrain (DT) method for the generation and propagation of turbulence in the computational domain. LES simulations are carried out with the DT method on two wind-tunnel (WT) benchmark case studies proposed by the Architectural Institute of Japan (AIJ) and widely adopted in the scientific literature: (1) an isolated building (2) a cluster of buildings. Then, the LES results are compared to the WT results of AIJ. A good agreement is found in terms of the mean and turbulence properties of the wind velocity for the two case studies. The level of accuracy achieved from the LES-DT results establishes its reliability for wind flow modeling for various environmental applications.

Wind-Driven Rain (WDR) loading on building facades is a crucial factor for designing sustainable and climate-resilient buildings and preserving historical buildings. WDR loading on buildings has been studied previously but results for such a multi-parameter problem are not generally conclusive. Thus, the relevant provisions of ISO semi-empirical model cannot be applied with confidence for complex building configurations, such as those in urban areas given that the estimated WDR can be more than twice of the field measurements. This paper aims to evaluate the effectiveness of two WDR techniques, namely Lagrangian Particle Tracking (LPT) and Eulerian Multiphase (EM), combined with the steady-state standard k-ω RANS turbulence model (referred to as RANS-LPT and RANS-EM). The results obtained from the RANS-EM approach are compared with the RANS-LPT results reported in the literature for a six-story mid-rise residential building located in Vancouver, Canada. The study considers 13 distinct rainfall events, including stand-alone and urban area configurations with and without overhangs. The RANS-EM and RANS-LPT approaches are evaluated by comparing modeled wind and WDR against wind-tunnel and on-site WDR measurements, respectively. The study found that the RANS-EM requires less computational time and provides more accurate results for the test building situated in an urban area compared to the RANS-LPT.

The effect of crosswind loads on buildings has been studied since the 1980s, but only a few researchers reported on the nonlinear response of tall buildings under ultimate crosswind loads. Performance-based wind design procedures provide a structurally efficient and economical alternative to prescriptive code based design, however their establishment necessitates further research in the following areas: i) development of a straightforward procedure for the derivation of reliable wind time-history loadings from wind tunnel data; ii) assessment of the dynamic behavior of tall buildings excited by wind in the full range of response: linear-nonlinear-near collapse; and iii) quantification of the effect of directionality on building performance in the full range of response. Herein, local aerodynamic data are used to produce reliable estimations of the directional alongwind and crosswind timehistory loadings for a 15-storey steel braced frame hospital building, in Montreal, Canada. The case study is designed to withstand the code-based wind and earthquake loads, as independent load combination cases. Then, advanced finite element models are employed to assess the effect of directional alongwind and crosswind loads on the building performance under increasing levels of input wind motion. Ten excitation angles from 0 degrees to 90 degrees are considered. Incremental dynamic analysis is employed to assess the building performance under recurring winds, including the wind directionality effect. To monitor fatigue failure, the rainflow counting method is used to approximate the number and amplitude of loading cycles exhibited by ductile brace members of the lateral force resisting system.

CFD is a valuable tool for assessing Wind-Driven Rain (WDR) loading, one of the most important environmental loads for fa & ccedil;ade design. The majority of previous studies on this topic have primarily concentrated on simple building configurations, i.e., stand-alone buildings. Hence, prior findings may not be applicable to consider the impact of upstream buildings in urban areas, which significantly alter wind flow field, consequently, change WDR loadings on downstream building facades compared to the stand-alone building. Part A: four different steady-state RANS models (i. e., standard k - omega, realizable k - epsilon, RNG k - epsilon, and standard k - epsilon) coupled with the Eulerian Multiphase (EM) technique (RANS-EM) are compared and implemented using OpenFOAM-7. These models are validated and verified based on wind-tunnel and field measurement data obtained from the literature for a six-story mid-rise residential building located in an urban area in Vancouver, Canada. The study considers 13 distinct rainfall events, for the test building with/ without overhangs. All four RANS models are deemed suitable for modeling WDR in urban areas, while the steady-state standard k-omega RANS-EM approach without incorporating turbulent dispersion showing slightly better performance, thus utilized for the reminder of the study. Part B: a sensitivity analysis is presented on how the upstream buildings influence the WDR loading on a downstream building, denoted as Obstruction Factor. A comparison between the CFD and ISO semi-empirical model shows significant discrepancies, potentially reaching up to factors of 5. Thus, updated Obstruction Factors are suggested to enhance the ISO model for more accurate estimation of WDR loads.

This paper describes in detail experimental investigations into the flat-roof pressures of buildings with four non-rectangular shapes —L, U, T, and X— in an atmospheric boundary wind tunnel. The results reveal that the distribution of wind loads on the outer roof corners and edges of buildings with non-rectangular plans resembles that experienced by a rectangular building. However, the wind loads on the inner perimeter area were observed to be higher than those recorded on the edges of a typical rectangular roof.