Concrete folded plate structures have gained increasing use and popularity in the United States during the past fifteen years. They have proved to be especially economical in the construction of longspan roof systems. The folded plate shape has come into wide use because of its low coat of construction for long spans, high load carrying capacity, and rigidity. Moreover, the folded plate structure hu the structural advantage of thin shelled, curved surface structures, and is much easier and less expensive to construct than the latter. With reference to folded plate structures continuous over a support, the problem arises of relating the geometry of the folded plates to a number of points along the entire length of the plate edges, in an attempt to find the true condition of stress at these points, and to find the contribution of each stress condition to the overall effect. The investigation of this thesis consists of analyzing a reinforced folded plate concrete roof, continuous with overhang. The method of analysis used is that of successive iteration, i.e. balancing angle changes against internal moments and/or stresses. This method is similar to one presented by Howard Simpson - “Design of Folded Plate Roofs” - in the ASCE Proceedings, Vol. 84, January, 1958, but extended to apply to the cantilevered folded plates. / Master of Science

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering Johannesburg, 2016 / This dissertation presents a parametric study conducted on the dimensions of an inverted box rib (IBR) sheet. The objectives of the study were (i) to obtain the optimum dimensions that would be used to simulate new IBR profiles made from standard sheet input coils whilst meeting the stiffness criterion; and (ii) to perform a cost analysis to determine the most economic simulated profile. The dimensions which were varied in the parametric study were rib-height, rib-width, sheet thickness and the number of pans per 686 mm cover width of a single IBR 686 sheet. Numerical experiments were conducted using the Finite Elements Method and Abaqus/CAE software. The results were compared to the predictions obtained from Euler-Bernoulli beam theory. The outputs from the experiments were the sheet deflection from which stiffness was determined, and eigenvalues from which the profiles’ stability and buckling modes were calculated. This study found that sheet stiffness increased as the rib-height, sheet thickness and number of pans per 686 mm cover width increased. In contrast, the rib-width had little effect on the sheet stiffness. Hence, it was concluded that, for any IBR sheet profile, the rib-width should be kept at approximately 23 mm to avoid using more material in the sheet. The optimum dimensions found were rib-height of 34 mm, rib-width of 23 mm and four pans per 686 mm cover width. The commercially available IBR 686 sheet is made up of four pans and has a rib-height and a rib-width of 37 and 33 mm, respectively. It is manufactured from an input sheet coil of 925 mm. Reducing the rib-height from 37 mm to 34 mm and the rib-width from 33 mm to 23 mm resulted in increasing the cover width by 8 %. The optimum dimensions were further used to simulate profiles made from the 925, 940, 1000, 1175, 1219, 1225, 1250 and 1320 mm standard sheet coils in order to find the most economic IBR profiles that met the stiffness criterion. The 1250 mm coil yielded the most economical IBR profile, which has six 97 mm wide pans, and a 996 mm cover width. This profile resulted in a 10 % cost saving compared with the next closest profile. / MT2017

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. / This dissertation has as it's objective to develop an expert system for the purpose of investigating the suitability of using expert systems in developing areas. It is the first time to our knowledge that an expert system has been tested for usage in such a context. The housing and more specifically roofing domain is investigated for an application topic resulting in "the selection of suitable roofing types" being chosen. Potential end-users are identified, an appropriate context of such a system is outlined and an expert system tool is selected, The knowledge engineering and building of the knowledge base are described. Feedback from the parties involved in testing and validating BUILDROOF is documented. In addition the suitability of using expert systems in the developing areas context in which BUILDROOF was developed, is discussed. Finally, recommendations regarding potentially suitable areas of application for expert systems in developing areas are outlined. / Andrew Chakane 2019

The advent of new standards in wireless communication like the Long Term Evolution (LTE) has resulted in a need for newer and better design of receivers for wireless communication systems, the first step of which is to design a tunable integrated filter on the receiver front end. In this work we propose a new design for a passive tunable integrated Roofing filter for LTE bands. The role of the Roofing filter is to protect the rest of the circuitry from overloading and distortions caused due to large out-of-band signals. This filter protects the rest of the circuitry and hence it gets the name Roofing filter. The Roofing filter is present on the receiver front-end. The filter has a low insertion loss and a high return loss at the input. The bandwidth of the Roofing filter is around 200MHz at the highest values. The filter uses off-chip inductors. The filter has a continuous center frequency tuning range of 2GHz from 0.7GHz to 2.7GHz, which is the allocated frequency range for LTE bands. This continuous tuning is achieved by the use of MOSFET based varactors. The filter is a narrowband filter. The design is implemented in TSMC 65nm CMOS technology.

In the past few years, there has been a growing concern for the impact of non-renewable resource depletion and environmental degradation as a result of energy consumption in buildings. Buildings account for approximately one-half of the total energy consumption in developed countries. As architects and engineers involved with the fast growing building industry, we have the responsibility of exploring and integrating various renewable energy sources into our buildings to help us move towards what we might call "Positive Energy Architecture", where the role of the building shifts from net energy consumer to net energy producer. The object of this study is to analyze how different parameters namely solar radiation, temperature, solar altitude and solar azimuth affect the power produced by a new thin film photovoltaic panel. Through the application of multiple linear regression, the model developed is then used to evaluate the cost-effectiveness of the building integrated photovoltaic roofing system when connected to the utility grid when compared to a conventional roofing system. The analysis is applied to a school building located in Blacksburg, Virginia. Using the current utility rates and the energy consumption data, the payback period of the system is evaluated for full roof, half roof and quarter roof coverage. / Master of Science

No description available.

The diploma thesis deals with the study of runoff torrential rain on the green roofing. This work is focused the problematics of runoff for various constructions of flat and green roofing. The results were evaluated according to the standard ČSN 75 67 60 - Internal sewerage and the German standart for green roofing FLL.

Highly reflective roofing systems have been analyzed over several decades to evaluate their ability to meet sustainability goals, including reducing building energy consumption and mitigating the urban heat island. Studies have isolated and evaluated the effects of climate, surface reflectivity, and roof insulation on energy savings, thermal load mitigation and also ameliorating the urban heat island. Other sustainable roofing systems, like green-roofs and solar panels have been similarly evaluated. The motivation for the present study is twofold: the first goal is to present a method for simultaneous evaluation and inter-comparison of multiple roofing systems, and the second goal is to quantitatively evaluate the realized heating and cooling energy savings associated with a white roof system compared to the reduction in roof-top heat flux. To address the first research goal a field experiment was conducted at the International Harvester Building located in Portland, OR. Thermal data was collected for a white roof, vegetated roof, and a solar panel shaded vegetated roof, and the heat flux through these roofing systems was compared against a control patch of conventional dark roof membrane. The second research goal was accomplished using a building energy simulation program to determine the impact of roof area and roof insulation on the savings from a white roof, in both Portland and Phoenix. The ratio of cooling energy savings to roof heat flux reduction from replacing a dark roof with a white roof was 1:4 for the month of July, and 1:5 annually in Portland. The COP of the associated chillers ranges from 2.8-4.2, indicating that the ratio of cooling energy savings to heat flux reduction is not accounted for solely by the COP of the chillers. The results of the building simulation indicate that based on energy savings alone, white roofs are not an optimal choice for Portland. The benefits associated with cooling energy savings relative to a black roof are offset by the winter-time penalty, and the net benefit from adopting white roof technology in Portland is small. That said, there are other potential benefits of white roofing such as impact on urban heat islands and roof life that must also be considered.

Este trabalho apresenta uma comparação de propriedades entre o cimento asfáltico de petróleo (CAP-20) e o mesmo CAP-20 modificado pela utilização de diferentes tipos de borrachas, visando avaliar uma alternativa para minimizar os problemas ambientais causados pela disposição de pneus usados. Foram preparadas misturas contendo 4, 8 e 12% em massa de SBS (estireno-butadieno-estireno) e Borracha Moída de Pneus (BMP) em duas granulometrias diferentes. Os comportamentos dessas misturas foram avaliados pelos ensaios de: penetração, ponto de amolecimento, separação de fase, resistência à tração, alongamento, flexibilidade, deformação permanente e recuperação elástica. Os resultados mostraram que é possível dispersar borracha de pneu em asfalto, embora os valores obtidos para as propriedades medidas não sejam tão favoráveis quanto às obtidas com SBS. / This work presents a comparison of properties between a CAP-20 asphalt and the same CAP modified using different kinds of rubbers, as a way to evaluate an alternative to minimize the environmental problems related to the disposal of used tires. Mixtures with 4, 8 and 12 wt% of SBS and two different particle size of scraped tire were prepared. The behaviors of these mixtures were evaluated by penetration, softening point, phase separation, tensile strength, elongation, flexibility, permanent deformation and elastic recovery tests. The results showed that it is possible to disperse tire rubber in asphalt, although the values obtained for some of the measured properties are not as good as the ones obtained with SBS.

Thesis (M.A.)--Boston University / The City of Boston land use has altered the surrounding watersheds through creation of infrastructure, damming, landfill, and expansion of impervious surfaces. The continued growth of the City has historically outstripped the capacity of its combined storm and sanitary sewer system, necessitating discharges into area water bodies. In light of model forecasts by the Intergovernmental Panel on Climate Change predicting precipitation increases it is likely the already strained system will need additional capacity. Boston's tradition of expanding artificial capacity is compared to the City of Curitiba's enhanced natural capacity stormwater management plan. Limitations in both are discussed and the author concludes the City of Boston would benefit from increasing decentralized natural capacity through green rooftechnology. To investigate this claim remote sensing data was analyzed over three neighborhoods. The resulting available green roofing area was then combined with historical climate data to create a retention response model. The extrapolated city-wide model predicted retention of 19%-27% of total building received rainfall from 1983-2009. This model was then correlated with Combined Sewer Overflow (CSO) discharge National Pollutant Discharge Elimination System report data. The retention volume was found to accommodate most discharges in the FY2009 as well. Thus, extensive green roof technology presents a supplemental capacity building strategy for the City of Boston to avoid increases in future CSOs.