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Call number: LD2668 .T4 1951 S65 / Master of Science

M.Ing. / The purpose of this investigation was to develop a double concrete pole which could be used as an angle- or terminal structure for overhead power lines. To act as a double pole, shear flow must be transferred effectively between the two single poles to create the new stronger section. The method to transfer the shear flow must also be practical and economical...

MSc., Faculty of Science, University of the Witwatersrand, 2011 / A hierarchical non-linear model was developed for the time-dependent shrinkage behaviour of South African concretes, from historical laboratory data. The fit of fifteen growth curve models to the shrinkage-time profiles was evaluated and MCDA was used to identify the best model. The three parameters of the chosen growth curve model were modelled in terms of covariates (relating to concrete raw materials, concrete composition and shrinkage testing conditions) by multivariate multiple regression to produce the WITS model. The model largely conformed to existing knowledge about the factors affecting concrete shrinkage. Published models for concrete shrinkage were compared to the WITS model regarding their predictive ability with respect to the South African data set. The WITS model performed the best across a variety of graphical and numerical goodness-of-fit measures. The importance of the study is two-fold:  The concept of hierarchical non-linear modelling has been applied for the first time to the modelling of the time-dependent properties of concrete.  This is the first comprehensive model to bring together laboratory data on the shrinkage of concrete generated in South Africa over a span of thirty years.

In recent years, high strength concrete (HSC) is becoming an attractive alternative to traditional normal strength concrete (NSC), and is used in a wide range of applications. With the increased use of HSC, concern has developed regarding the behavior of such concrete in fire. Until now, the fire performance of HSC is not fully understood and more research is needed. Full-scale fire testing is time consuming and expensive, and the real fire scenario is different from the standard fire. Performance-based assessment methods, including numerical analysis and simplified method, are being accepted in an increasing number of countries. In this dissertation, the fire testing results both of HSC and NSC are presented, performance-based numerical models are developed to study the fire performance of reinforced concrete (RC) members, and simplified calculation methods are proposed to estimate the load capacity of fire-damaged RC columns/beams. A detailed and comprehensive literature review is presented that provides background information on the high temperature behavior of concrete materials and RC members, as well as information on fire performance assessment procedures and objectives. The fire testing results of seven batches of HSC and NSC are presented and discussed. The test results indicated that the post-fire re-curing results in substantial strength and durability recovery, and its extent depends upon the types of concrete, temperature level, and re-curing age. The fire tests also showed that violent explosive reduced the risk of HSC explosive spalling. The surface crack widths were also reduced during the re-curing process, and in most cases, they were found within the maximum limits specified by the American Concrete Institute (ACI) building code. / Numerical models are developed herein to investigate the behavior in fire of RC columns and beams. The models have been validated against fire test data available in literature, and used to conduct parametric studies, which focused on the size effect on fire resistance of RC columns, and the effect of concrete cover thickness on fire endurance of RC beams. Simplified calculation methods have been developed to predict the load capacity of fire damaged RC columns/beams. This method is validated by five case studies, including thirty-five RC columns tested by other investigators. The predicted results are compared with the experimental results, and the good agreement indicates the adequacy of the simplified method for practical engineering applications. / by Lixian Liu. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

This study presents and illustrates a methodology to calculate the capacity of an existing reinforced concrete bridge under a non-conventional blast load due to low and intermediate pressures. ATBlast program is used to calculate the blast loads for known values of charge weight and stand off distance. An excel spreadsheet is generated to calculate ultimate resistance, equivalent elastic stiffness, equivalent elastic deflection, natural period of the beam, the maximum deflection, and the maximum rotation in the support for a simple span solid slab and T-Beam bridges. The allowable rotation could be taken as to two degrees. Naval Facility Engineering Command (NAVFAC) approach was adopted, where the inputs were material properties, span length, and area of reinforcement. The use of the Fiber Reinforced Polymer for increasing the capacity of an existing bridge is also presented in this study. Parametric studies were carried out to evaluate the performance of the solid slab and T-Beam bridges under the assumed blast load. / by Firas A. Abdelahad. / Thesis (M.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, FL : 2008 Mode of access: World Wide Web.

by Kwok Kin Wing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 126-128. / Acknowledgement / Abstract / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- General Background --- p.1 / Chapter 1.2 --- Previous Studies on Injection Moulded Short Fibre Reinforced Composites --- p.4 / Chapter 1.3 --- Scope of the Present Work --- p.6 / Chapter 2. --- Theory --- p.8 / Chapter 2.1 --- Elastic Moduli of Injection Moulded Short Fibre Reinforced Composites --- p.8 / Chapter 2.1.1 --- Elastic Properties of an Anisotropic Solid --- p.10 / Chapter 2.1.2 --- Elastic Moduli of a Unidirectional Lamina --- p.12 / Chapter 2.1.3 --- Laminate Theory for the Elastic Moduli of Short Fibre Reinforced Composites --- p.21 / Chapter 2.1.4 --- Out-of-Plane Elastic Moduli of Injection Moulded Short Fibre Reinforced Composites --- p.31 / Chapter 2.2 --- Thermal Conductivity of Injection Moulded Short Fibre Reinforced Composites --- p.32 / Chapter 2.2.1 --- Thermal Conductivity of a Unidirectional Lamina --- p.32 / Chapter 2.2.2 --- Laminate Theory for the Thermal Conductivity of a Multidirectional Laminate --- p.35 / Chapter 2.2.3 --- In-plane Thermal Conductivity of Injection Moulded Short Fibre Reinforced Composites --- p.36 / Chapter 3. --- Expeirimental Techniques --- p.37 / Chapter 3.1 --- Determination of the Elastic Moduli by Ultrasonic Techniques --- p.37 / Chapter 3.1.1 --- Theory of Measurement --- p.37 / Chapter 3.1.2 --- Ultrasonic Measurement --- p.40 / Chapter 3.2 --- Determination of the Thermal Diffusivity by Laser Flash Radiometry --- p.49 / Chapter 3.2.1 --- Theory of Measurement --- p.49 / Chapter 3.2.2 --- Thermal Diffusivity Measurement --- p.51 / Chapter 3.3 --- Fibre Orientation and Length Measurements --- p.57 / Chapter 3.4 --- Density Measurement --- p.58 / Chapter 4 . --- Results and Discussion --- p.60 / Chapter 4.1 --- Composites and Polymers Studied in the Present Work --- p.60 / Chapter 4.2 --- Elastic Moduli and Thermal Conductivity of the Fibres and Polymer Matrices --- p.60 / Chapter 4.3 --- Fibre Orientation and Aspect Ratio --- p.67 / Chapter 4.4 --- Elastic Moduli of the Composites --- p.74 / Chapter 4.4.1 --- General Features --- p.74 / Chapter 4.4.2 --- Comparison between Theory and Experiment --- p.77 / Chapter 4.5 --- Thermal Conductivity of the Composites --- p.90 / Chapter 4.5.1 --- Thickness and Width Dependence of the Thermal Diffusivity of the Composites --- p.90 / Chapter 4.5.2 --- Comparison between Theory and Experiment --- p.104 / Chapter 5. --- Conclusion --- p.113 / Chapter Appendix A --- Tables of Data --- p.115 / References --- p.126

Orientador: Cesar Fabiano Fioriti / Resumo: O crescimento da população e do seu poder aquisitivo mudaram a geração de resíduos. Atualmente se produz resíduos diferentes em qualidade e volume diferentes daqueles produzidos por gerações passadas. Entre os resíduos gerados atualmente se encontram os resíduos de PET, oriundos de embalagens descartáveis, que acarretam problemas ambientais devido ao descarte incorreto. Este trabalho se propõe em estudar a aplicação destes resíduos para a produção de pavers de concreto, observando suas características de desempenho em relação aos pavers produzidos com concreto convencional, ambos produzidos por procedimentos manuais. Para atingir o objetivo proposto foram realizados ensaios de trabalhabilidade, ensaios de massa específica em estado fresco e endurecido, ensaios de absorção de água, medição da incorporação de ar, ensaios de resistência à compressão, tração e impacto e microscopia eletrônica de varredura para os traços produzidos com 5%, 10%, 15% e 20% de substituição em volume dos agregados miúdos e graúdos. Dessa maneira, foi possível buscar informações a respeito do comportamento obtido por meio da substituição parcial dos agregados pelos resíduos de PET produzindo peças com características semelhantes àquelas proporcionadas pelos pavers convencionais, atingindo a resistência à compressão de 35 MPa, definida em norma, em 4 traços produzidos, mesmo com valores de absorção superiores aos 6% estipulados em norma. / Abstract: Population growth and purchasing power changed waste generation. Currently the wastes produced differs in quality and volume than that produced by past generations. Amongst the waste currently produced are the PET waste, originating from disposable packaging, which generate environmental problems due to incorrect disposal. The purpose of this work is to study the application of these residues in concrete pavers production, observing the performance characteristics in comparison to those produced with conventional concrete, both produced by manual procedures. To achieve the proposed goal were performed workability tests, specific weight in both fresh and hardened conditions, water absorption tests, air content tests, compressive strength, splitting tensile strength and impact tests and scanning electron microscopy for the concrete designs containing 5%, 10%, 15% and 20% by volume of both fine and coarse aggregate. Thus, it was possible to achieve information about the concrete behavior produced with partial substitution of the aggregates by the PET waste, producing pavers with similar characteristics of those provided by pavers produced with conventional concrete, achieving the compressive strength of 35 MPa, required by standard, in 4 mixtures with substitution, although the absorption values were above the 6% required by standard. / Mestre

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