Abstract Understanding and quantifying the effects of aerodynamic interference is fundamental to designing safe and efficient buildings; however, there is a complexity in this phenomenon that characterizes it as the greatest challenge of wind engineering and thus limits improving design guidelines in a normative way. Therefore, this study investigated the impacts of building interference on wind-induced loads on a tall building through wind tunnel tests conducted using the synchronous pressure measurement technique. This impact was quantified using the interference factors (IFs) on the along-wind, across-wind and torsional force coefficients, which were mapped considering different wind angles, relative positions and number of buildings, in addition to the terrain roughness. It was observed that the protection effect in a static analysis is a dominant phenomenon in most studied scenarios when there is wind interference. The largest extension of the amplification zones occurred in scenarios in which the wind blew against the smallest facade of the analyzed building and the largest facade of the interfering building, where the coefficient of torsional moment was more sensitive to changes in wind turbulence. buildings however way Therefore windinduced induced technique IFs (IFs alongwind, alongwind along wind, along-wind acrosswind across coefficients angles roughness turbulence

Resumo Compreender e quantificar os efeitos de interferência aerodinâmica é fundamental para projetar edifícios seguros e eficientes, no entanto, há uma complexidade nesse fenômeno que o caracteriza como o maior desafio da engenharia do vento e, por tanto, limita o aprimoramento das diretrizes de projeto de maneira normativa. Logo, essa pesquisa investigou o impacto da interferência de edificações nas cargas induzidas pelo vento em um edifício alto, através de testes em túnel de vento conduzidos utilizando a técnica de medição de pressão síncrona. Esse impacto foi quantificado por meio dos fatores de interferência (FIs) nos coeficientes da força longitudinal, transversal e torcional, os quais foram mapeados considerando diferentes ângulos de vento, posições relativas e quantidade dos edifícios, além da rugosidade do terreno. Observou-se que o efeito de proteção em uma análise estática é um fenômeno dominante na maioria dos cenários estudados quando há interferência do vento. A maior extensão das zonas de amplificação ocorreu nos cenários em que o vento incidiu na menor fachada do edifício analisado e na maior fachada do edifício interferente, onde o coeficiente do momento torcional mostrou-se mais sensível às mudanças de turbulência do escoamento do vento. eficientes entanto tanto normativa Logo alto síncrona FIs (FIs longitudinal terreno Observouse Observou se interferente mostrouse mostrou

ABSTRACT Introduction: The study of the determination of the wind load on buildings is of great importance due to the occurrence of strong winds in the territory of Cuba that cause damage to buildings. The present work shows the results of the investigations that contributes to the improvement of the determination of the wind load for the calculation of the structures. Methods: The research was developed through computational numerical modeling, experimental analysis at a reduced and real scale and statistical methods of extreme values. Results: The results obtained are the updating of the basic design speeds and vertical profiles of wind speed; updating the wind turbulence parameters; proposal of aerodynamic coefficients for photovoltaic panels, elements of reticulated towers and communication antennas; updating the dynamic methods for the calculation of structures and the calibration of models using modal experimental techniques (OMA). Conclusions: the most modern international techniques were acquired and applied to the study of the action of the wind on constructions. Significant results have been incorporated into the Cuban Wind Code and have already been implemented in the new designs of photovoltaic parks, latticed towers and tall buildings that are built in the country contributing to reduce vulnerability of structures.

RESUMEN Introducción: El estudio de la determinación de la carga de vientos sobre las edificaciones es de gran importancia debido a su ocurrencia en el territorio de Cuba ocasionando daños en las construcciones. Las investigaciones estuvieron encaminadas a: la actualización de las velocidades básicas de diseño y perfiles verticales de velocidad de viento; la actualización de los parámetros de la turbulencia del viento; propuesta de coeficientes aerodinámicos para paneles fotovoltaicos, elementos de torres reticuladas y antenas de comunicación; la actualización de los métodos dinámicos para el cálculo de estructuras y la calibración de modelos mediante técnicas experimentales modales (OMA). Métodos: La investigación se desarrolló a través de la modelación numérica computacional, análisis experimental a escala reducida y real y métodos estadísticos de valores extremos. Resultados: Los resultados obtenidos consisten en la actualización de las velocidades básicas de diseño y perfiles verticales de velocidad de viento; la actualización de los parámetros de la turbulencia del viento; propuesta de coeficientes aerodinámicos para paneles fotovoltaicos, elementos de torres reticuladas y antenas de comunicación; la actualización de los métodos dinámicos para el cálculo de estructuras y la calibración de modelos mediante técnicas experimentales modales (OMA). Como conclusiones, se logran incorporar las más modernas técnicas a nivel internacional al estudio de la acción del viento en las construcciones, estos avances obtenidos se incorporan a la norma cubana de viento y ya han sido implantados en los nuevos diseños de parques fotovoltaicos, torres reticuladas y edificios altos que se construyen en el país, contribuyendo de esta manera a la reducción de la vulnerabilidad estructural.

resumo: A atualização do mapa de isopletas da norma NBR 6123 – Forças devidas ao vento em edificações – é um dos aspectos tratados no âmbito do trabalho da comissão encarregada da revisão da citada norma. Tradicionalmente estes mapas são elaborados por meio de análises de valores extremos das velocidades do vento registradas em estações meteorológicas, da aplicação de métodos estatísticos para caracterização dos dados, e de interpolação matemática para geração do mapa. Entretanto, a distribuição espacial dos fenômenos atmosféricos responsáveis por ventos fortes no Brasil não pode ser desconsiderada. Este trabalho apresenta uma proposta para um novo mapa de isopletas da velocidade básica do vento para a NBR 6123 elaborado com base em uma abordagem climatológica e em recente pesquisa incluindo novos dados de centenas de estações meteorológicas. Inicialmente foi desenvolvido um mapa de regiões climáticas associadas aos fenômenos que produzem ventos fortes, a partir do qual o mapa de isopletas foi traçado. Resultaram isopletas associadas a velocidades de vento variando entre 30 e 48m/s.

abstract: Updating the basic wind speed map of NBR 6123 –-Wind loading on buildings – is one of the duties of the committee responsible for the revision of this code. Traditionally such maps are elaborated by means of extreme value wind speed data collected at meteorological stations, use of statistical methods for data characterization, and application of mathematical regression to elaborate the territorial maps. However, the spatial distribution of the atmospheric phenomena responsible for strong winds cannot be disregarded. This work presents a proposal for a new wind speed map for NBR 6123 combining a climatological approach and wind speed data recently compiled from hundreds of meteorological stations. A climatological wind map was first produced considering the phenomena which cause strong winds, and used as a basis to draw the isopleths of the basic wind speed map, considering the measured wind speed data. The resulting map shows basic wind speeds ranging from 30 to 48m/s.

Abstract Wind-induced loading on buildings may be altered due to presence of upwind structures. These variations are quantified by the interference factors (IFs), which is determined experimentally for each case analyzed, since obtaining this quantification in codes and standards is still impractical due to the complexity of the multi-parameters involved. To understand the influence of some of these parameters on the interference effects, contour plots and power spectra density were presented for IFs corresponding to aerodynamic coefficients of the along-wind and cross-wind force, as well as for torsion. Wind tunnel tests were conducted applying the synchronous pressure measurement technique. Interference arrangements with one and two upstream interfering buildings were investigated for different wind angles, relative positions and terrain roughness. Results indicate that the shielding effect is predominant in most of the studied cases. Nevertheless, the amplification effects are generally present in specific configurations and are usually caused by channeling and buffeting effects, as well as vortex shedding. Windinduced induced structures IFs, , (IFs) analyzed multiparameters multi involved alongwind along crosswind cross force torsion technique angles roughness cases Nevertheless shedding (IFs

Abstract The increasing verticalization of urban environments led to the consideration of loads influenced by horizontal forces arising from the action of the wind. Different neighborhood densities alter the flow behavior and reflect on interference effects. An extensive study developed in the wind tunnel through aerodynamic characterization in the reduced model of the CAARC building, simulated with the insertion of distinct windward neighborhood densities in three configurations, I (one interfering model), II (two models) and III (three models), with different relative positions between the models, D and 2D, where D is the smallest dimension of the model, aiming to understand the interaction relationship between such parameters. Based on the results, both the insertion and number of interfering buildings, and the variation in spacing, influence on the determination of the coefficients. The results indicated that the FV values are mainly given as a function of the proximity and size of buildings directly in the surroundings, most forces on the x-axis have been increased (96.2%), on y-axis, most actions have been reduced (65.4%).

ABSTRACT The objective of this paper is to obtain the form coefficients of a two-equal leg angle section, not reflected in the wind load calculation standards used in Cuba for the construction of triangular-based self-supporting telecommunication towers. An experimental test was carried out in the Joaquim Blessmann wind tunnel, belonging to the Federal University of Rio Grande do Sul, for angles of attack between 0º and 180º with intervals of 15º. The obtained results allow to demonstrate the independence of the form coefficients of the Reynolds number and of the turbulent strenght of the flow. The corrected form coefficients are reported as a result of the blockage effect, obtaining the highest values in the attack angles of 0º and 30º.

RESUMEN El presente trabajo tiene como objetivo obtener los coeficientes de forma de una sección compuesta por dos angulares de alas iguales, no reflejada en las normas de cálculo de carga de viento, utilizada en Cuba para la construcción de torres de telecomunicaciones autosoportadas de base triangular. Para ello fue realizado un ensayo experimental en el túnel de viento Joaquim Blessmann, perteneciente a la Universidad Federal de Rio Grande do Sur, para ángulos de ataque entre 0º y 180º con intervalos de 15º. Los resultados obtenidos permiten demostrar la independencia de los coeficientes de forma del número de Reynolds y del contenido de turbulencia del flujo. Se reportan los coeficientes de forma corregidos producto del efecto de bloqueo, obteniéndose los mayores valores en los ángulos de ataque de 0º y 30º.

ABSTRACT: The Alcântara Launch Center (ALC) is the Brazilian gate to the space located at the north coast of Maranhão State, close to the Equator. Topographical local characteristics modify the parameters of incident atmospheric winds and it can cause great influence on the gas dispersion process. In this work, detailed scale models of the ALC region was experimentally evaluated using a wind tunnel. The topographical scale models were built where mean and fluctuating flow characteristics were analysed in order to understand the real behaviour of ALC winds and then, simulations of the effluent dispersion process were made using these scale models. The wind velocity was measured by a hot wire anemometer and the concentration fields in the proximities of a gas emission source were analysed by an aspirating probe connected to the anemometer system. The results obtained show similarity with numerical outputs from previous study in the case of the emission at ground level. A coherent behaviour with the physic of the phenomena was observed for the case of emission downward.

Abstract This paper presents a series of results with respect to the mean values of shear, base moment and torsion acting in a building obtained through an experimental wind tunnel study using the standard building proposed by the Commonwealth Advisory Aeronautical Research Council (CAARC) as building reference. In the loading determination, the interference of a neighboring building with similar geometric characteristics to the CAARC was simulated, considering variations of positioning and spacing in relation to the reference building. It was concluded that the presence of the neighboring building increased the mean loads in the reference building for a significant number of directions considered. In the case of the considered deviations and the proposed provisions by this study, it was concluded that the vicinity factor that would contemplate the majority of the results obtained in the tests should increase the wind loads by at least 60% in relation to the values obtained for the building reference considered in isolation.

Abstract A numerical investigation is performed in this work in order to evaluate the aerodynamic performance of building cross-section configurations by using corner modifications. The CAARC tall building model is utilized here as reference geometry, which is reshaped considering chamfered and recessed corners. The numerical scheme adopted in this work is presented and simulations are carried-out to obtain the wind loads on the building structures by means of aerodynamic coefficients as well as the flow field conditions near the model’s location. The explicit two-step Taylor-Galerkin scheme is employed in the context of the finite element method, where eight-node hexahedral finite elements with one-point quadrature are used for spatial discretization. Turbulence is described using the LES methodology, with a dynamic sub-grid scale model. Predictions obtained here are compared with experimental and numerical investigations performed previously. Results show that the use of corner modifications can reduce significantly the aerodynamic forces on the building structures, improve flow conditions near the building locations and increase the Strouhal number, which may have an important influence on aeroelastic effects.