The Benefit of Horizontal Photovoltaic Panels in Reducing Wind Loads on a Membrane Roofing System on a Flat Roof

The present paper proposes a measure for improving the wind-resistant performance of photovoltaic systems and mechanically attached single-ply membrane roofing systems installed on flat roofs by combining them together. Mechanically attached single-ply membrane roofing systems are often used in Japan. These roofing systems are often damaged by strong winds, because they are very sensitive to wind action. Recently, photovoltaic (PV) systems placed on flat roofs have become popular. They are also often damaged by strong winds directed onto the underside, which cause large wind forces onto the PV panels. For improving the wind resistance of these systems, we proposed to install PV panels horizontally with gaps between them. Such an installation may decrease the wind forces on the PV panels due to the pressure equalization effect as well as on the waterproofing membrane due to the shielding effect of the PV panels. This paper discusses the validity of such an idea. The pressure on the bottom surface of a PV panel, called the “layer pressure” here, was evaluated by a numerical simulation based on the unsteady Bernoulli equation. In the simulation, the time history of the external pressure coefficients, measured at many points on the roof in a wind tunnel, was employed. It was found that the wind forces, both on the PV panels and on the roofing system, were significantly reduced. The reduction was large near the roof’s corner, where large suction pressures were induced in oblique winds. Thus, the proposed method improved the wind resistance of both systems significantly.

Wind-Induced Dynamic Behavior of Mechanically Attached Single-Ply Membrane Roofing Systems Installed on Flat Roofs

The present paper investigates the wind-induced dynamic behavior of a mechanically attached single-ply membrane roofing system installed on flat roofs of middle-rise and high-rise buildings with or without parapets. First, the wind pressure distributions on the roof were measured in a turbulent boundary layer. The results indicate that the parapets affect the wind pressure distributions significantly. Very large peak suctions are induced near the windward corner of the roof in an oblique wind in the case of a building without parapets. Then, we have developed a test method for evaluating the wind-resistant performance of the roofing system using three Pressure Loading Actuators (PLAs) and a chamber to which a full-scale specimen is attached. In the experiments, the chamber was divided into three spaces by using thin silicon sheets. The PLAs generated different fluctuating pressures in these spaces using the time history of wind pressure coefficients measured at three points near the windward corner of the roof in an oblique wind. We measured the membrane deformations and the wind forces acting on the fasteners connecting the membrane with the structural substrate. The results indicate that horizontal forces nearly equal to or larger than the vertical ones are generated on the fasteners, which may cause pulling out of fasters more easily. The failure mode was found to be different from that obtained from a ramped pressure loading test. We have also developed a model of finite element analysis, which was validated by an experiment. The results of analysis for a wide area of roofing system indicate that relatively large horizontal forces may be generated on the fasteners in the field region of the roof for buildings with parapets.

Affordable Roofing System with Square and Rectangular Dome Panels

Affordable roofing is a word, which refers to residence units or habitation units whose prices are assumed/expected to be affordable or economical to a category of community with an identified remuneration limit or scale. Structural roofs are taken in to computation for considerable or valuable price of building in ordinary condition. Thus some savings accomplished in roofing operation or roofing system, significantly decreases the price of the structural units or building unit. In India, BMTPC (Building material and technology promotion council) and HUDCO ( Housing and urban development corporation limited) are the main tow organization or council who have been advertising or promoting appropriate building material and construction technologies in different territory or division of the country. In this roofing, systemized, standardized, advanced roofing units or parts have been used to avoid the temporary structures like shuttering. Hence, the roofing will be economical and progress of work is fast which ensures better in quality. Even though the studies, experiments or researching on this affordable roofing system as not been completely utilized as in other sector or region, a concentrated examination or exploration is to be done to verify the prefabricated roofing which would change the common roofing procedure. The major requisite of choosing affordable roofing system is to develop or advance the rapidity in construction and to decrease the price. In the current work, staadpro software is used for designing the precast RCC roofs and analysis of joist by analytical study using the finite element method. The outcomes which manifest the satisfactory volume of price or cost depletion for various set of panels. In this design, we have considered two least dimensions of 0.5m and 0.75m panels. The aspect ratios which is varying from 1 to 2 and the price depletion is of 0.4% to 9.4% for the least dimension of 0.5m panels. Likewise aspect ratio varying from 1 to 2 with a price depletion from 19.7% to 34.7% for a least dimensions of 0.75m panel size. As the size of the panels increases it becomes cost effective. The preferred roofing system was found to be more cost beneficial as compared with regular RCC roofing system with the increase in dimension of the slab. The roofing system is designed considering M20 concrete and fe415 steel. The beam system panels are precasted and can be easily placed in the position. 3 to 5 masons are enough to easily handle the loads of panels and primary, secondary beam because of weights of panels are less as compare to Conventional slabs. The affordable roofing systems requires lesser time for construction when compare to conventional RCC slab. The major advantage of this roofing is that false roofing works is not required for the dome shaped portion. This dome shaped portion sealing gives good attractive or decorative appearance. The cost analysis made between conventional roofing system and proposed roofing system indicates a cost reduction or depletion of 40% when compare to RCC slab of same size.

Prediction and Performance Investigation of Polyurethane Foam as Thermal Insulation Material for Roofing Sheet Using Artificial Neural Network

The prediction and application of Polyurethane Foam in developing roofing sheets cannot be over-emphasized when considering the environmental changes coursed by thermal radiation. This paper presents an artificial neural network application to model and predict the indoor temperature resistance of polyurethane (PU) roofing in residential buildings. The study employed a data logger to measure the indoor and outdoor temperatures for three simulation environments (i.e., morning, afternoon, and evening) for two hours each. Furthermore, the authors employed the Levenberg-Marquardt algorithm to transform and predict the indoor temperature obtained in the residential building's polyurethane roofing house. The result shows that the PU roofing system could absorb the heat and reduce the house model's temperature with 6.9% in the morning, afternoon 15.8%, and 6.8% in the evening when compared with the temperature outdoor environment. The ANN was also able to train, test, and validate the experimental temperature results with 92.86%, 93.92%, and 95%, respectively. The mean square error and a testing error occurs at 0.1707 and 0.1689. Therefore, this study concluded that ANN's application in predicting the thermal insulation material such as the PU roofing system is highly efficient and will increase the manufacturer's performance evaluation. It has also created significant awareness of the community in employing the PU roofing system for residential buildings, which will reduce the rate of energy consumption in buildings.

Acoustic Design of Ancient Buildings: The Odea of Pompeii and Posillipo

In this paper, a typology of a building erected in Ancient Greece and Ancient Rome is described: the Odeon. The Odeon is a covered building, but more modest in size than traditional open-air theatres without roofs. The Odeon could hold a few hundred spectators and therefore a smaller audience. The roof covering allowed the possibility of meetings even in adverse weather conditions. The etymology of the word of the Odeon (covered theatre) means the place of the ode, or of the songs. In this paper are discussed the architectonic and acoustic characteristics of the Odea of Pompeii and Posillipo. With commercial software (Odeon, Room Acoustics Software, Lyngby Denmark) we assess the acoustic characteristics of the Odea of Pompeii and Posillipo in the presence of an original roofing system and show that these buildings were well suited for music, songs and speech.