Henor Artur de Souza

Ventilação natural em galpões: o uso de lanternins nas coberturas

Natural ventilation inside constructions allows both favorable conditions for thermal comfort to the occupants and quality improvement of the internal air. The efficiency of natural ventilation in a building is associated to the number, position, type and size of the existing openings for the passage of air. It is also associated to the combined action of wind forces and temperature differences. In the case of building industrial hangars and commercial facilities, it is usual to construct openings in the roofs (skylight with an entrance and an exit), besides openings in the facades. This work focuses on the natural ventilation in hangars through the use of skylights in the roofs. It presents a mathematical modeling, associated with the concept of the natural ventilation index. A numerical simulation was used to analyse both the air flow inside the hangar and the internal temperature profile. The airflow and the temperature profile were obtained by simulation. The obtained results took into account the degree of necessary thermal comfort inside the hangar. The results present the necessary size of the opening to obtain adequate internal conditions of comfort.

Ventilação natural como estratégia para o conforto térmico em edificações

Appropriate natural air circulation within a structure reduces the thermal gradient, and contributes towards internal air renewal. This latter is important because, depending on the profile of occupation of the environment, the lack of this process can be harmful to the health. This type of circulation is an efficient alternative for the reduction of the consumption of energy in the conditioning of buildings. In this research, we studied natural ventilation, driven by the combined action of the forces of wind and thermals. The efficiency of the single sided and cross natural ventilation is evaluated, using the numerical method of the finite elements with the software AN SYS. The numeric model is used to determine the effects of the force of the winds and the combined thermal forces, resulting in the airflow and the temperature distribution. The results obtained are compared with the results of empiric models, whereby it was observed that the efficiency of the cross ventilation is around 3.5 times higher than the single sided ventilation, increasing the vortexes in the airflow inside the environment.

Dados climáticos para avaliação de desempenho térmico de edificações

Building thermal performance is an important factor in habitations, especially for those destined for people of low income. Buildings properly projected for the climate surrounding them provide comfort and save energy. The evaluation of a buildings thermal performance includes a global picture of the architectural project in relation to the thermal exchanges between the built atmosphere and the external atmosphere, where the characterization of the local climatic conditions is one of the most important stages. Local values such as solar radiation schedules, temperature, and relative humidity of the air as well as predominant wind speed characterize the conditions of building exposure to the climate. With respect to thermal performance evaluation, the climatic data are characterized by typical project days for winter and summer periods. Such days are determined in function of its frequency of occurrence that represents levels of requirements in the evaluation. In this article a methodology is presented to estimate the typical days of the project, through statistical treatment of climatic data.

Acoustical vibration characterics of prefabricated panels employed in industrialized construction

With the development of industrialized steel construction, new constructive elements have been brought not only to the market, but to the everyday construction site as well and, in this way professionals and users have questioned their efficiency. In respect to vibrations in floors, what can be detected is that floor structures are thinner and a decrease of the mass in the horizontal closing panels and the utilization of new materials and systems have led them to have lower natural frequencies, and so are nearer to the frequencies produced by walking. This decrease of mass of the closing panels also lead to a considerable weakness in terms of acoustical insulation, which can cause unfavorable conditions and discomfort. Thus, it becomes necessary to do detailed studies of the efficiency of the vibration and acoustical performance of the new systems to obtain the characterization and the qualification parameters in order to optimize their use. This study does a comparative evaluation of some kinds of horizontal and vertical closing systems in respect to the vibrational and acoustical insulation performance.

Acoustical and thermal performance of multilayer closing panels used in steel-structured buildings

This article provides an evaluation of the acoustical and thermal performance of some closing systems by referencing materials such as cement plates, plasterboard walls, precast concrete panels and expanded polystyrene. Reverberation time is calculated by applying an empirical formula, which uses temperature and relative air humidity values obtained from simulations that were conducted using the computational simulation program ESP-r (Energy Simulation Program-research). The internal temperature presented by the ESP-r is an indicator of thermal performance. Using a simplified graphic method, the acoustical performance is also evaluated by estimating the loss of sound transmission that occurs through the closing panels. Combinations of these panels, which form multilayer panels mediated by a layer of air and with or without insulating material between them, are applied. The results show that multilayered closing systems, when filled with insulating material, are an efficient solution than can provide adequate acoustical and thermal performance.

REFORÇO DE VIGAS DE MADEIRA COM ELEMENTOS DE AÇO

Neste trabalho propoem-se o reforco com elementos estruturais metalicos, insercao de perfis metalicos T e colagem de chapa de aco, em elementos estruturais em madeira, dando origem a uma estrutura mista de madeira e aco. A madeira a ser recuperada e analisada experimentalmente e por meio de uma abordagem numerica, pelo metodo dos elementos finitos, avalia-se o desempenho dos reforcos metalicos propostos, em um estudo de caso. A abordagem numerica e realizada via software ANSYS, considerando uma viga mista de madeira e aco bi-apoiada, com carregamentos uniformemente distribuidos. Os reforcos propostos, colagem de chapa de aco na base da viga e insercao de perfil T, apresentaram desempenho de 36% e 39%, respectivamente. A recuperacao de estruturas em madeira com pecas metalicas e muito vantajosa, uma vez que a peca de madeira nao tem quase nenhuma perda. Este tipo de intervencao possui maior exatidao e a construcao e muito rapida, deixando o ambiente de trabalho mais limpo.

Morro do Cruzeiro UFOP Campus evaluation of indoors climatic conditions

The comfort conditions of a given environment can directly influence the performance of the activities performed therein. When considering the school space in relationship with the user, the environment is even more important, since it may reflect fully on the learning process. This article evaluates the thermal comfort perceptions of classroom users of the Federal University of Ouro Preto, specifically the School of Mining, the Institute of Physical and Biological Sciences and the Building Block of Classrooms. The research is conducted through questionnaires and measurements of environmental variables in loco simultaneously in the three areas throughout the months of June, July and September 2011. The results were statistically analyzed using the calculation of the standard deviation from the mean operative temperature and humidity to give comfort zone. Approximately 75% of the users were satisfied with the thermal environment.

Influence of the type of fastening of multi-layered closing panels on the estimate of the sound transmission loss

Industrialized closing systems appear as rational solutions in steel-structured construction. These closing systems, consisting of multi-layered panels, have been applied in projects where it is intended to obtain a high sound transmission loss without raising the cost and without using a lot of mass. However, acoustic isolation depends on several factors, including the type of connection between the panels, requiring a preliminary study of the acoustic performance of the closing system to prevent future interventions. This paper uses a simplified graphical method to evaluate the influence of the type of connection (line-line, line-punctual or punctual-punctual) of industrialized closing panels on the estimation of the sound transmission loss that occurs across the wall constituted by these panels. The panels are combined, forming multi-layered closings interleaved by a layer of air, either without or with a sound-absorbing material between them. The results show that it is necessary to check the effectiveness of each type of fastening of the closing systems because, for example, for the frequency range between 500 and 2,000 Hz, the sound transmission loss of a closing system consisting of cementitious plate with glass wool and line-punctual and punctual-punctual connections exceeds in 6.25% the sound transmission loss of the same system with line-line fastening. For a system composed of expanded polystyrene with glass wool, the sound transmission loss provided by line-line fastening exceeds in 7.0% the sound transmission loss of the same closing system with line-punctual and punctual-punctual fastenings.

Manifestação patológica em estruturas metálicas e mistas. Prédio da Escola de Minas UFOP

Structures , steel , concrete and wood do not last indefinitely , deteriorate over time and fail to reach their useful life if not properly designed , implemented , used with criteria and finally submitted to a preventive maintenance. The objective of this study is to evaluate the physical condition of the building of the School of Mines Federal University of Ouro Preto checking the main pathologies found . This work was carried out from a discipline master being divided into two stages : first a literature within the context of pathologies in steel and composite structures as well as within the subject building maintenance and then conducted a case study with a review the physical conditions of the building of the School of Mines , Federal University of Ouro Preto UFOP Minas Gerais. The present exploratory study in order to achieve field study to enhance the knowledge presented. Two areas were defined to be mapped on the ground floor , first block of the building . The first page in exactly the same access and the second , next to the first access to the public baths , still on the ground floor . Cameras , tape and plugs to catalog the

Influência da inércia térmica do solo e da ventilação natural no desempenho térmico: um estudo de caso de um projeto residencial em light steel framing

No Brasil, a tecnologia do sistema light steel framing comecou a ser aplicada casas residenciais somente no final da decada de 1990. Por ser uma tecnologia importada dos Estados Unidos e com uma linguagem arquitetonica tipica do pais de origem, e necessario que algumas adaptacoes dos projetos sejam feitas para adequar seu desempenho termico. Neste trabalho avalia-se o desempenho termico de uma edificacao unifamiliar projetada em light steel framing, considerando-se algumas estrategias de ventilacao natural e a influencia da inercia termica do solo em Belo Horizonte, MG. Na determinacao do comportamento termico do modelo utiliza-se o programa computacional EnergyPlus, seguindo as seguintes etapas: caracterizacao da edificacao, das condicoes tipicas de exposicao ao clima, do perfil de ocupacao, das exigencias humanas, configuracao do sistema de fechamento e avaliacao das condicoes de conforto termico nos ambientes em concordância com as normas especificas. Observou-se que a estrategia de ventilacao natural, quando adequadamente utilizada, em funcao das condicoes climaticas locais, proporciona uma melhora significativa no desempenho termico da edificacao. Da mesma forma, em funcao da topografia do terreno e da caracteristica do projeto, observou-se que a influencia da inercia termica do solo somente se torna positiva quando associada as estrategias de ventilacao natural e de sombreamento.