A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg 2017 / The present study investigates the possibility of designing a catenary barrel vault, which can be implemented in regions where extreme tropical storms are frequently experienced. It moreover investigated the effect of non-uniform wind loads on catenary barrel vaults, and how to solve for these load conditions efficiently. The effects of high, non-uniform wind loads were assessed, and possible solutions were explored to determine a structurally efficient solution in resisting the loads applied. Different analysis and design techniques were explored in this research. These techniques included the optimization of the geometry, in resisting the applied loads most efficiently, as well as the structural design of the section in ensuring a durable and safe structure. The study revealed that the geometry of the structure cannot be optimised to resist the applied loads in a catenary fashion without external aid. By draping the vault in a post-tensioned basalt geogrid mesh, axial compression can be increased in the section and geometry optimisation can be achieved in resisting the applied loads in a catenary fashion. Three post-tensioning techniques were investigated and discussed. / MT 2018

Há diversos procedimentos para determinação dos carregamentos de vento. A norma NBR 6123/88 pode ser utilizada para determinação desses carregamentos e consequentes esforços para dimensionamento de estruturas. Entretanto há procedimentos não normativos que podem contribuir para determinação desses mesmos carregamentos. Um deles, que é empregado no presente trabalho, é o método do vento sintético. O objetivo desse trabalho é o de fazer uma análise comparativa entre as respostas obtidas na estrutura sujeita aos carregamentos dinâmicos, obtidos através do método do vento sintético, e as respostas obtidas com carregamentos estáticos gerados a partir de considerações da norma NBR 6123/88 – Forças devidas ao vento em edificações. A estrutura em estudo é uma torre de transmissão de energia elétrica, que é modelada no programa computacional RSTAB da Dlubal (DLUBAL, 2015), para determinação de suas características dinâmicas. Os carregamentos dinâmicos do vento para o método do vento sintético são gerados através de um algoritmo, utilizando-se do programa computacional Mathcad Prime, versão 3.0. Os carregamentos estáticos e dinâmicos são lançados na estrutura para determinação de deslocamentos, esforços internos axiais e reações de apoio. Os resultados comparados demonstram que a abordagem que considera carregamentos gerados a partir da NBR 6123/88 é a mais conservadora, com valores de grandezas que excedem em até 132% valores obtidos a partir do método do vento sintético. / There are several procedures to determine the wind loadings. The Brazilian code NBR 6123/88 can be used to determine these loadings and the internal forces for structural design. However, there are non-normative procedures that may contribute to determining those same loads. One of them, which is used in this work, is the method of synthetic wind. The aim of this study is to make a comparative analysis of the responses obtained for the structure when subjected to dynamic loads, obtained through the synthetic wind method, and the responses obtained with static loads generated from considerations of NBR 6123/88 - Forces due to the wind on buildings. The structure under study is a power transmission tower, which is modeled in the software program RSTAB, developed by Dlubal, to determine its dynamic characteristics. Using the software Mathcad Prime 3.0 the dynamic wind loads are generated by an algorithm for the wind synthetic method. Static and dynamic loads are applied to in the structure to determine displacements, axial internal forces and support reactions. The compared results show that the approach that considers loadings generated from the NBR 6123/88 is the most conservative, with magnitude values that exceed up to 132% values obtained from the synthetic wind method.

Uma importante estratégia de projeto para melhorar o desempenho térmico das edificações em climas quentes e úmidos é a adoção conjunta da ventilação natural e de dispositivos de sombreamento. Contudo, quando a ventilação natural é ocasionada pela ação dos ventos nas edificações, as pressões do vento nas envoltórias da edificação são alteradas com a presença de elementos externos próximos que mudam as características do fluxo incidente. Deste modo, o presente trabalho tem como objetivo avaliar os impactos na ventilação natural, e nas temperaturas internas do ar e/ou no conforto térmico de uma habitação térrea em um clima quente e úmido, a partir do uso de diferentes dispositivos de sombreamento externos e muro. Para isso, foram realizadas simulações computacionais no programa EnergyPlus através do módulo AirflowNetwork. Foram realizados ensaios em túnel de vento de Camada Limite Atmosférica (CLA) para a obtenção dos coeficientes de pressão (Cps). Os resultados apontaram impactos específicos a cada elemento estudado, no entanto o fenômeno mais frequente nos casos com dispositivos de sombreamento foi a redução dos efeitos de sobrepressão e sucção. Quanto aos seus impactos nas renovações de ar, estes provocaram uma diminuição do fluxo de ar e, consequentemente, o aumento da temperatura no período predominantemente noturno. Entretanto, foi observado um maior impacto na atenuação das temperaturas internas nos períodos diurnos, que prevaleceu sobre o aumento nos períodos de ventilação. Destacou-se, dentre os dispositivos de sombreamento estudados, as proteções tipo veneziana por proporcionarem um melhor desempenho térmico. Já os muros, dentre todos os elementos estudados, foram os que tiveram maior impacto nos Cps. Tal fenômeno significou a diminuição da taxa de renovação de ar dentre 50 e 75%. O impacto mais sobressalente nas temperaturas internas nestes casos foi o aumento destas no período noturno, limitando o potencial da ventilação natural para a remoção de calor da edificação / An important design strategy for improving the thermal performance of buildings in hot and humid climates is the adoption of natural ventilation strategies and shading devices combined. However, when natural ventilation is wind-driven, the wind pressures on the building envelope are altered by the presence of nearby external elements that change the incident flows characteristics. Thus, the present work aims to evaluate the impacts on natural ventilation, and the internal air temperatures and/or the thermal comfort of a single ground floor low-cost house in a hot and humid climate, considering the use of different external shading devices and walls. For such, computational simulations were performed in the EnergyPlus program using the AirflowNetwork module. Atmospheric Limit Wind (CLA) wind tunnel tests were performed to obtain pressure coefficients (Cps). The results indicated specific impacts to each element studied, however the most frequent phenomenon in cases with shading devices was the reduction of the effects of overpressure and suction. As for their impacts on air changes rate, they caused a decrease in airflow and, consequently, an increase in temperature predominantly in the nocturnal period. However, a greater impact was observed in the attenuation of internal temperatures in the daytime periods, which prevailed over the increase in ventilation periods., Among the shading devices studied, venetian type protections for providing better thermal performance were highlighted. Among all the elements studied, the walls had the greatest impact on the Cps. This phenomenon meant the reduction of the air changes rate between 50 and 75%. The most significant impact on internal temperatures in these cases was the their increase at night, limiting the potential of natural ventilation to the removal of heat from the building.

Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: The use of air-cooled steam condensers (ACSCs) is the preferred cooling method in the chemical and power industry due to stringent environmental and water use regulations. The performance of ACSCs is however highly dependent on the influence of windy conditions. Research has shown that the presence of wind reduces the performance of ACSCs. It has been found that cross-winds (wind perpendicular to the longest side of the ACSC) cause distorted inlet flow conditions, particularly at the upstream peripheral fans near the symmetry plane of the ACSC. These fans are subjected to what is referred to as '2-D' wind conditions, which are characterised by flow separation on the upstream edge of the fan inlets. Experimental investigations into inlet flow distortion have simulated these conditions by varying the fan platform height. Low platform heights resulted in higher levels of inlet flow distortion, as also found to exist with high cross-wind speeds. This investigation determines the performance of various fan configurations (representative of configurations used in the South- African power industry) subjected to distorted inlet flow conditions through experimental and numerical investigations. The similarity between platform height and cross-wind effects is also investigated and a correlation between system volumetric effectiveness, platform height and cross-wind velocity is found. / AFRIKAANSE OPSOMMING: Die gebruik van lugverkoelde stoom kondensors (LVSK's) word verkies as 'n verkoelingsmetode in die chemiese- en kragvoorsieningsindustrie as gevolg van streng omgewings- en waterverbruiksregulasies. Die werkverrigting van LVSK's word egter grootliks beïnvloed deur die teenwoordigheid van wind. Navorsing het gewys dat die teenwoordigheid van wind die werkverrigting van LVSK's verminder. Daar was gevind dat kruiswinde (wind loodreg tot die langste sy van die LVSK) versteurde inlaat vloeitoestande veroorsaak, veral by waaiers wat aan die stroomop kant van die LVSK naby die simmetrievlak geleë is. Hierdie waaiers word blootgestel aan na wat verwys word as '2-D' windtoestande wat gekenmerk word deur vloeiwegbreking wat plaasvind by die stroomop rand van die waaierinlate. Eksperimentele ondersoeke van inlaat vloeiversteurings het hierdie toestande gesimuleer deur die waaier platformhoogte te verstel. Lae platform hoogtes het gelei tot hoër vlakke van inlaat vloeiversteuring, soortgelyk aan wat gevind word met hoë kruiswindsnelhede. Hierdie ondersoek gebruik numeriese en eksperimentele metodes om die werkverrigting van verskeie waaierkon gurasies (verteenwoordigend van kon- gurasies wat gebruik word in die Suid-Afrikaanse kragvoorsieningsindustrie) wat blootgestel word aan versteurde inlaat vloeitoestande te bepaal. Die ooreenkoms tussen platformhoogte en kruiswind e ekte word ook ondersoek en 'n korrelasie tussen die sisteem volumetriese e ektiwiteit, platformhoogte en kruiswindsnelheid word bepaal.

This thesis presents the distribution of strong wind and wind pressure in the Greater Victoria area associated with winter mid-latitude cyclones based on climate data from the School-Based Weather Station Network during 6 selected days in the winters of 2006, 2007 and 2008. The objectives of this study are i) to test whether synoptic conditions favourable to severe mid-latitude cyclonic storms that are well described in the literature were associated with the selected storms, ii) to determine the time patterns of high wind speed and its direction and maximum gusts, iii) to test necessity of considering the spatial variation in air density and its controls in general assessments of the spatial variation in wind pressure and wind damage potential in the local area, iv) to identify potential areas susceptible to wind damage. Observations taken every second were from Davis Vantage Pro2 TM Plus weather stations located on the southern edge of school building roofs. Thirty-minute means and gust wind speeds were used. All six storms went north of Victoria. The synoptic conditions associated with the selected mid-latitude cyclones agreed with the ones described in literature. Strongest winds at most stations were generally from the southwest, and multiple wind speed peaks were found. The daily iii  maximum gust wind speeds were found before and/or after the highest mean wind speed peak. The spatial variation in air density and its controls were found to be negligible. Although there are a number of interacting causes of the distribution, strongest winds were at stations with smooth surrounding surfaces, close to the southern shoreline, on exposed slopes and/or near relief constrictions. The area with greatest wind speeds and damage potential was found from the east of downtown extending to Lansdowne Middle School. This study provides new knowledge of winds in the Greater Victoria area and contributes to people’s better response to wind storms, land use planning and forecasting severe windstorms. / Graduate / 0368 / mmatsuda@uvic.ca

This thesis presents the distribution of strong wind and wind pressure in the Greater Victoria area associated with winter mid-latitude cyclones based on climate data from the School-Based Weather Station Network during 6 selected days in the winters of 2006, 2007 and 2008. The objectives of this study are i) to test whether synoptic conditions favourable to severe mid-latitude cyclonic storms that are well described in the literature were associated with the selected storms, ii) to determine the time patterns of high wind speed and its direction and maximum gusts, iii) to test necessity of considering the spatial variation in air density and its controls in general assessments of the spatial variation in wind pressure and wind damage potential in the local area, iv) to identify potential areas susceptible to wind damage. Observations taken every second were from Davis Vantage Pro2 TM Plus weather stations located on the southern edge of school building roofs. Thirty-minute means and gust wind speeds were used. All six storms went north of Victoria. The synoptic conditions associated with the selected mid-latitude cyclones agreed with the ones described in literature. Strongest winds at most stations were generally from the southwest, and multiple wind speed peaks were found. The daily iii  maximum gust wind speeds were found before and/or after the highest mean wind speed peak. The spatial variation in air density and its controls were found to be negligible. Although there are a number of interacting causes of the distribution, strongest winds were at stations with smooth surrounding surfaces, close to the southern shoreline, on exposed slopes and/or near relief constrictions. The area with greatest wind speeds and damage potential was found from the east of downtown extending to Lansdowne Middle School. This study provides new knowledge of winds in the Greater Victoria area and contributes to people’s better response to wind storms, land use planning and forecasting severe windstorms. / Graduate / 0368 / mmatsuda@uvic.ca

Uma importante estratégia de projeto para melhorar o desempenho térmico das edificações em climas quentes e úmidos é a adoção conjunta da ventilação natural e de dispositivos de sombreamento. Contudo, quando a ventilação natural é ocasionada pela ação dos ventos nas edificações, as pressões do vento nas envoltórias da edificação são alteradas com a presença de elementos externos próximos que mudam as características do fluxo incidente. Deste modo, o presente trabalho tem como objetivo avaliar os impactos na ventilação natural, e nas temperaturas internas do ar e/ou no conforto térmico de uma habitação térrea em um clima quente e úmido, a partir do uso de diferentes dispositivos de sombreamento externos e muro. Para isso, foram realizadas simulações computacionais no programa EnergyPlus através do módulo AirflowNetwork. Foram realizados ensaios em túnel de vento de Camada Limite Atmosférica (CLA) para a obtenção dos coeficientes de pressão (Cps). Os resultados apontaram impactos específicos a cada elemento estudado, no entanto o fenômeno mais frequente nos casos com dispositivos de sombreamento foi a redução dos efeitos de sobrepressão e sucção. Quanto aos seus impactos nas renovações de ar, estes provocaram uma diminuição do fluxo de ar e, consequentemente, o aumento da temperatura no período predominantemente noturno. Entretanto, foi observado um maior impacto na atenuação das temperaturas internas nos períodos diurnos, que prevaleceu sobre o aumento nos períodos de ventilação. Destacou-se, dentre os dispositivos de sombreamento estudados, as proteções tipo veneziana por proporcionarem um melhor desempenho térmico. Já os muros, dentre todos os elementos estudados, foram os que tiveram maior impacto nos Cps. Tal fenômeno significou a diminuição da taxa de renovação de ar dentre 50 e 75%. O impacto mais sobressalente nas temperaturas internas nestes casos foi o aumento destas no período noturno, limitando o potencial da ventilação natural para a remoção de calor da edificação / An important design strategy for improving the thermal performance of buildings in hot and humid climates is the adoption of natural ventilation strategies and shading devices combined. However, when natural ventilation is wind-driven, the wind pressures on the building envelope are altered by the presence of nearby external elements that change the incident flows characteristics. Thus, the present work aims to evaluate the impacts on natural ventilation, and the internal air temperatures and/or the thermal comfort of a single ground floor low-cost house in a hot and humid climate, considering the use of different external shading devices and walls. For such, computational simulations were performed in the EnergyPlus program using the AirflowNetwork module. Atmospheric Limit Wind (CLA) wind tunnel tests were performed to obtain pressure coefficients (Cps). The results indicated specific impacts to each element studied, however the most frequent phenomenon in cases with shading devices was the reduction of the effects of overpressure and suction. As for their impacts on air changes rate, they caused a decrease in airflow and, consequently, an increase in temperature predominantly in the nocturnal period. However, a greater impact was observed in the attenuation of internal temperatures in the daytime periods, which prevailed over the increase in ventilation periods., Among the shading devices studied, venetian type protections for providing better thermal performance were highlighted. Among all the elements studied, the walls had the greatest impact on the Cps. This phenomenon meant the reduction of the air changes rate between 50 and 75%. The most significant impact on internal temperatures in these cases was the their increase at night, limiting the potential of natural ventilation to the removal of heat from the building.

Moisture loads arising from the deposition of wind-driven rain (WDR) on building façades can induce detrimental effects to wall assembly components and can adversely influence their long-term performance. Wind-driven rain as a climatic phenomenon will inevitably be affected by the evident changing climate in the near future. Wall assemblies subjected to wind-driven rain loads will also perform differently due to a varying moisture environment over the course of time. The performance of the building envelope, including the wall assembly, largely determines the serviceability of a building over its life cycle. Thus, it is essential for practitioners to understand and to be able to assess such performance. In this study, a complete procedure has been developed to permit assessing the moisture resilience of wall assemblies to wind-driven rain loads arising from climate change. The development of this procedure included four phases. In the first phase the historical and projected climate data was analysed to identify the possible wind-driven rain conditions to which a wall assembly may be exposed. The magnitudes of wind-driven rain and driving-rain-wind-pressure for different return periods were also investigated. Based on the results from phase one, a watertightness test protocol was established taking into consideration the possible ranges of wind-driven rain and driving-rain-wind-pressure as they may occur spatially, as well as temporally, across Canada. The range of watertightness test parameters was accommodated in the newly built Dynamic Wind and Wall Testing Facility (DWTF) at the National Research Council Canada. Thereafter in phase two of the research, wall assemblies having different configurations were tested in the DWTF following the test protocol to obtain the moisture load for wall assemblies under different wind-driven rain conditions. Such moisture loads were formulized and used in the third phase, where hygrothermal simulations were conducted to derive the hygrothermal parameters of the wall assemblies subjected to historical and projected climate data. In the final research development phase, different criteria and methods were explored to describe the performance of wall assemblies based on the hygrothermal parameters. During the development of the moisture resilience assessment procedure, a novel wind-driven-rain-pressure-index was devised to describe the extent of the effects arising from the concurrent action of wind-driven rain and driving-rain-wind-pressure loads on a vertical wall assembly; a new two-step approach was established to formulize the watertightness test results and thereby permit calculating the moisture load using values of hourly wind-driven-rain and hourly driving-rain-wind-pressure of a given location; a novel severity index was proposed to quantitatively describe the damage events arising from such moisture load on the wall assemblies. The moisture performance of tested wall assemblies subjected to historical and projected future climate were compared and discussed. The risks of occurrence of damage events in wall assemblies during different time periods were also demonstrated.

Уточнена методика определения ветровых нагрузок на здания в ANSYS CFX на основе анализа сходимости полученных результатов с результатами физического моделирования. / The method for determining wind loads on buildings in ANSYS CFX has been refined based on the analysis of the convergence of the obtained results with the results of physical modeling.