This thesis presents an analysis and experimental verification for a multilayer beam in bending. The formulation of the theoretical analysis includes the combined effect of shear and geometric nonlinearity. From this formulation, a finite element program (CUBES) is developed. The experimental tests were done on multilayer, corrugated paper beams. Failure deflections and loads are thus obtained. The experimental results are reasonably predicted by the numerical results. Based upon this comparison, a maximum compressive stress is determined for the tested beam. Finally, design curves for the tested beam are drawn using the determined maximum compressive stress and the finite element program. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

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Thesis (MScEng)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: A multi-purpose beam/column apparatus is developed to ensure successful testing of structural elements and to optimise the main test floor of the Structures Laboratory of the University of Stellenbosch. An overview of the testing of structural elements is given as background to beam and column testing, with specific reference to the test sample, the test arrangement and the test data. The test arrangement, with reference to the test setup boundary conditions (static and kinematic), and the loading are discussed. A summary of the collection and the processing of the test data is given and frequently used and standard test setup is described. The requirements and the various components of the testing apparatus are discussed and a three-dimensional CAD model of the apparatus is developed to illustrate the versatility of the apparatus. A rational planning process is developed to optimise the testing and pre-test planning process with specific reference to the use of the apparatus. This rational planning process is defined as the process of preparing, testing and evaluating structural tests and together with the literature review will ensure meaningful test results. The use of the apparatus, built by the Department of Civil Engineering, University of Stellenbosch and the use of the rational planning process are illustrated by testing the deflection of a welded truss, from which conclusions are drawn. / AFRIKAANSE OPSOMMING: 'n Veelsydige balkkolom apparaat is ontwikkel om die gebruik van die hoof-toetsvloer van die Struktuur Laboratorium van die Universiteit van Stellenbosch te optimiseer en suksesvolle struktuurtoetse te verseker. As agtergrond tot die ontwikkeling van die MTA word 'n oorsig gegee oor balk-en-kolom toetse, met spesifieke verwysings tot die toetsstuk, die toets-opstelling en die toets-data. Die toets-opstelling word bespreek met spesifieke verwysing na die grenstoestande (staties en kinematies) en die aangewende belasting. Die versameling en die verwerking van toetsdata en die algemeen gebruikte en standaard toets-opstellings word bespreek. Die vereistes van die verskillende komponente van die apparaat word bespreek en 'n driedimensionele CAD model van die apparaat word gebruik om die veelsydigheid van die apparaat te beklemtoon. 'n Rasionele beplanningsproses, wat spesifiek verwys na die gebruik van die apparaat, word ontwikkel. Hierdie beplanningsproses wat die beplanning, uitvoer en evaluasie van strukturele toetse insluit, saam met die literatuur agtergrond, verseker sinvolle toetsresultate. 'n Gesweisde vakwerk word getoets om die gebruik van die apparaat, gebou deur die Departement van Siviele Ingenieurswese, Universiteit van Stellenbosch en die gebruik van die rasionele beplanningsproses te illustreer. Gevolgtrekkings word gemaak na aanleiding van hierdie toetse.

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Single plate connections for steel beams, connected by high strength bolts to the beam web and welded to the column, were investigated to determine their, behaviour. Tests were performed on the connections in the absence and in the presence of shear, and shear was found not to affect the rigidity of the connections. Varying the gauge distance, the weld size, the pitch and the number of bolts in the test specimens, showed that only the pitch and the number of bolts influenced the rigidity of the connections. An increase in the pitch and the number of bolts causes an increase in the rigidity of the connections. In all cases the major slip value was greater than the usually assumed value. Under the action of pure moment the centre of rotation was found to be slightly above the centroid of the connection, whereas under the action of moment and shear the centre of rotation was slightly below the centroid of the connection. The maximum moment developed by the connections varied from 45 kip-inches for the two-bolt connection, to 355 kip-inches for the six-bolt connection. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

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The fracture problem due to the singular stresses arising from the sudden change of geometric properties around cracks and notches was studied both analytically and experimentally. The failure models of the cracked and the notched specimens were derived by using linear elastic fracture mechanics methodology, which led to the determination of the critical stress intensity factors. Experiments were conducted to determine fracture toughness for different modes as well as the effect of variations in the crack-front width, specimen size and moisture content. Subsequently, failure surfaces for cracks and notches were developed based on the experiments undertaken, describing in each case the interaction between mode I and mode II fracture toughness. To verify the reliability of these experiments, the results obtained were compared with the published literature. As an application, design curves for a 90 degrees-cracked beam and a 90 degrees-notched beam are presented. These curves allow the prediction of the failure loads due to the rapid crack propagation under different loading conditions. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Failure of pitched-tapered glulam beams in tension perpendicular to grain has been attributed to the inadequacy of the present method of calculating stresses. In this thesis, the factors of time and size for tension perpendicular to grain were investigated to determine how they would affect the allowable stresses. A total of 229 Douglas Fir glulam blocks of two sizes were loaded for ?0 days in uniform tension perpendicular to grain to investigate time effect. Test data were analyzed by developing estimates for the strength ratios. Results indicate that strength reductions increase at an increasing rate with the logarithm of time. The presently used time factors were shown to be conservative and could be increased for the 2-month, the 7-day and the 1-day durations. Experimental data also indicate that the present time factors may be non-conservative for load durations less than 5 minutes and more than ?0 days. In addition, short-term testing of 24-0 Southern Pine glulam blocks of three sizes was performed to investigate size effect. Results show that the relationship between specimen strength and volume is a straight line in a log.-log. plot, thus verifying the weakest-link model for Southern Pine. Comparison with Douglas Fir data taken from literature was also made. It was found that Southern Pine is definitely stronger than Douglas Fir In tension perpendicular to grain. Size effect, however, is almost identical for the two species. Significant difference was observed in the long-term test results between the two specimen volumes. This may be due to the effect of size, but it could also be caused by the different stress levels used for the two volumes. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate