Recherche UO Research: Evaluation Of Performance Of Mechanically Attached Roofing Systems
Abstract: Roofing system is an integral part of a building envelope. Keeping the roofs in place against high wind events is a challenging task for architects and roof designers. There are two stages in the design process: first, a comprehensive understanding of the wind induced loads on the roof system and, second, an accurate estimation of the system response to the induced wind loads. The present study contributes to an ongoing research project at the National Research Council Canada in the evaluation of Mechanically Attached Roofing Systems (MAS) for wind uplift design. Accomplishments are grouped in two tasks. Task 1, applied finite element methods to investigate whether an analytical method can be used to predict fastener loads based upon uplift pressures and chamber geometry. Task 2, developed an experimental procedure to quantify the air leakage rate and identified its impact on the wind uplift resistance. The aspect ratio of the testing chamber plays a critical role in the evaluation of roofing system response.
This paper deals with the grouted pipe-roofing reinforcement method that is used in the construction of tunnels through weak grounds. This system consists on installing, prior to the excavation of a length of tunnel, an array of pipes forming a kind of 'umbrella' above the area to be excavated. In some cases, these pipes are later used to inject grout to strengthen the ground and 'connect' the pipes. This system has proven to be very efficient in reducing tunnel convergence. Water inflow when tunnelling through weak grounds. However, due to the geometrical and mechanical complexity of the problem, existing finite element frameworks are inappropriate to simulate tunnelling using this method. In this paper, a mathematical framework based on a homogenization technique to simulate 'grouted pipe-roofing reinforced ground' and its implementation into a 3-D finite element programme that can consider stage construction situations are presented. The constitutive model developed allows considering the main design parameters of the problem and only requires geometrical and mechanical properties of the constituents. Additionally, the use of a homogenization approach implies that the generation of the finite element mesh can be easily produced and that re-meshing is not required as basic geometrical parameters such as the orientation of the pipes are changed. The model developed is used to simulate tunnelling with the grouted pipe-roofing reinforcement method. From the analyses, the effects of the main design parameters on the elastic and the elastoplastic analyses are considered. Copyright © 2004 John Wiley & Sons, Ltd.
Choi is an approved OSHA outreach instructor for construction and industrial safety and serves as ASSE faculty advisor for the Student Safety Organization. There has been increased awareness for improving construction site safety while developing safety programs and increasing safety inspections (Jaselskis et al., 1996). However, the Bureau of Labor Statistics (BLS) shows that the construction industry sector recorded the rate of fatal occupational injuries and fatal falls from roofs increased to a new series high in 2004. Not only does the problem of injuries within the roofing industry cause a major concern for health and safety, but also additional effects of these injuries are the costs they invoke on many employers and insurers. The objectives of this study were to: (1) identify the role of the safety programs and management's opinions toward safety practices within roofing companies and (2) obtain detailed injury and illness types/body parts and determine how this information relates to costs. A two-page survey was designed and sent to residential and commercial roofing contractors in the Midwest.
Homes with metal roofs tend to sell for slightly higher values, likely because of the longevity of the material and its popularity in recent years. Homes with roofs made of asphalt shingles tend to sell for slightly less than their metal-roofed comparison points, but the age and maintenance quality of a shingle-roofed home will have a greater impact on the home's resale value than the material choice in most cases. Homes built in hot weather climates sometimes benefit from roofing with ceramic tiles or shingles, which can help to reflect and dissipate heat with their larger surface area. Though there are considerable design complications involved, homes able to support a roof composed of a soil base in which grasses and small plants can grow are often able to achieve significant energy efficiencies in all seasons, and the roofs themselves often experience next to no maintenance costs, apart from the maintenance of the structure supporting them. If notice have the money to invest in your home, the cosmetic and practical improvements of a metal roof are probably worth the input. Asphalt shingles are more common and finding roofing contractors prepared to immediately fix any asphalt shingle roof is fairly straightforward. Both roofing materials work. Have worked for decades.
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 matters more easily. The failure mode was found to be different from that obtained from a ramped pressure loading test. San Pedro Roofing 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.