Recent proposed rafter slenderness limits, to prevent snap-through of plastically designed pitched-roof portal frames, incorporate the elastic snap-through buckling load of such frames. It has been suggested that the elastic snap-through buckling load used in the proposals is over-estimated making these slenderness limits unconservative. This is supported by a more rigorous elastic analysis. To test the proposals, model frames lying on or close to the slenderness limits were tested to failure in the laboratory. Frame dimensions were chosen so that the frames were only susceptible to snap-through instability. Failure loads far lower than the expected plastic collapse loads were measured, showing that the elastic snap-through buckling load is over -estimated . Since plastic analysis is easily applied to portal frames, these slenderness limits are best replaced by a similar limit incorporating a more accurate elastic snap-through buckling load. A new limit is outlined which must still be tested by further research

The Base Test Method has been shown to be a viable means to predict the capacity of gravity loaded standing seam roof systems. However, for uplift loaded standing seam roof systems, the base test method is still being investigated. Previous tests conducted at Virginia Tech in 1990 and 1991 have led to the belief that scatter is inherent in the results of the base test method for uplift. It was found in this research that scatter does exist in the base test method for uplift loading. Tests were also conducted to determine if purlin size and span could be eliminated from a manufacturer's testing program. It could not be shown in this research that a relationship exists between the percentage of through-fastened capacity, 'R', and the constrained bending capacity of a purlin. / Master of Science

The objective of this thesis is to further investigate the base test method and to develop an analytical model which can accurately predict the failure of an uplift-loaded standing seam roof system. Four sets of full-scale tests were conducted and their results were analyzed along with previous results (Anderson 1991). It was found that by normalizing the data, a reduction factor could be established for each test set configuration. This reduction factor applies to both the base test and confirming multi-span test in each test set. Three analytical models were applied to predict the failure of the purlin. It was found that only the LaBoube Method accurately predicted the yield stress for only the simple span tests. It was determined that a variance exists in the failure loads of uplift-loaded standing seam roof systems which need to be investigated through testing. / Master of Science

The base tGSt method has been proposed by Carballo, Holzer and Murray [5] as a means of determining the strength of standing seam roof systems under gravity loading. The objective of this thesis is to evaluate the accuracy of the base test method. To do this, eleven sets of tests were performed at Virginia Polytechnic Institute & State University (VPl&SU). Each test set consisted of a single span base test from which a failure load was predicted for the corresponding three span confirming test. Results of two test sets recorded in Reference [5] were also used to evaluate the method. A secondary objective of this thesis is to comment on the effects that system components (purlin orientation, clip type, bracing configuration, panel type, insulation and purlin type) have on the strength of the system. Results from proprietary tests conducted at VPI & SU were used in conjunction with the results from this research to accomplish the secondary objective. / Master of Science

A roof over a manure reservoir eliminates the entry of precipitations, reduces odour and volatile gas emissions, lowers the storage and handling costs and alleviates environmental impacts. / Structural analysis and testing were carried out to establish the feasibility of geodesic domes as manure reservoir roofting. A stress analysis, conducted by computer was used to determine maximum compression loads on roof members. Compression tests were carried out in the laboratory to test two laminated designs and to evaluate the performance of a member joint. / Structural analysis showed that the Lamella type dome, with a diameter/height ratio of 4, offers the best geometry considering design criteria for manure roofs. Compression tests confirmed that laminated members, made of 38 x 89 mm and 38 x 140 mm pieces, can resist the design stress developed in a 22 meter diameter dome. / Loading tests revealed that non laminated wood members failed at 80% of the design load. However, the joints (formed by two 3,1 mm thick steel plates bolted to the members) were still able to resist an increase in loading. / Data obtained from the tests were used for a preliminary design of a geodesic roof taking into account specific conditions such as humidity and manure gas. However further study is required to adapt this concept to real conditions over a manure reservoir. / The cost of a 22 meter diameter dome, for covering manure reservoirs, is estimated at 79$/m$ sp2$ which is more expensive than the cost of the currently used, least expensive manure pit roof (wood truss design).

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

No description available.

The purpose of this thesis is to approach a partial theoretical understanding of the design of lamella structures and to determine the economic merit of the lamella structure as a structural steel hangar. A survey revealed no literature that discusses the design of lamella past the concept that the lamella could be designed as independent arches. In this thesis the analysis and design of the main structural steel members are attempted. In the analysis of the hangar it is assumed that the intersecting arches will not interact under load. The effect of the error of this assumption is minimized by furnishing partial support to the free edge of the lamella system by the use of an arch that spans the structure at the transverse edge. The effect of this edge arch is to cause the maximum stresses to occur in the interior of the lamella system where the interaction is minimized by the symmetry of the system. The method of analysis is a combination of graphic statics and virtual work. Graphic statics was used to determine the pressure line of the arches and virtual work summations were used to determine the redundant loads and reactions. At the conclusion the structure is compared on a tonnage of steel basis, with a structure of the same approximate size composed of steel rigid frames. / Master of Science

Insignificant diurnal variations make the reliance on thermal inertia to ameliorate the thermal discomfort in the hot humid region impossible. Natural ventilation, therefore, is not only important, but the velocity of air that gets into the living area is crucial. Various ways of creating negative pressure (a process of increasing the interior air speed) are examined. The performance of roof types with different horizontal openings in enhancing interior air movement was investigated in an open throat wind tunnel. The results indicate a significant difference in the interior air velocity with roof type A opening type 1 (see fig. 27 and fig. 28). The thesis explores other ways of creating climate adapted architecture in providing acceptable comfort level in the hot humid climate. Warm humid climates are defined, and data for one example (Lagos, Nigeria) are analysed. Comfort zones are established relative to the region being investigated and the methods of limiting interior heat gain are described. The effects of orientation, cross ventilation and material choice are discussed. / Master of Architecture

Diaphragm braced strut-purlins are commonly used in the roof systems of metal buildings. However, the design problem of combined uplift and axial loads on these members is not adequately addressed in the 1989 AISI specification. The objective of this thesis is to provide experimental evidence that strut-purlins can be designed with an existing interaction equation. It was a/so the objective of this thesis to find a method of determining the axial capacity of diaphragm braced strut-purlins and to experimentally verify the accuracy of the method. / Master of Science