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Composite beams are now widely used in infrastructure such as steel-framed bridges, buildings and stadiums. Most of these composite beams have been built with welded shear studs due to the availability of detailed research on their properties, and standard design methods for using them. However, as composite beams age, their ability to withstand current and future loading requirements deteriorates. On the other hand, existing composite beams incorporating welded shear studs cannot be easily retrofitted to prolong their useful service life, nor can the steel and concrete components of these beams be separated securely to be reused due to the permanent fixing mechanism of the welded studs. This thesis attempts to investigate the design and behaviour of composite beams with innovative bolted connectors. The novel fixing mechanisms of these bolted connectors may enable composite beams to be retrofitted reliably and also be disassembled without much effort. With these aims in mind, the emphasis in this thesis is primarily on the following issues: investigating the ability of bolted and welded-stud connectors to achieve composite action in normal and retrofitted composite beams investigating the effects of time-dependent creep and shrinkage of concrete on the behaviour of composite beams incorporating either bolted connectors or welded-stud connectors investigating the feasibility of dismantling composite beams subjected to serviceability loading by removing connector bolts. This thesis comprises many experimental and numerical studies, including the flexural behaviour of composite beams with bolted and welded-stud connectors as well as the load–slip behaviour of the connectors. In addition, the behaviour of the beam and push-out test specimens in their respective experiments was simulated using finite element models developed in ABAQUS software. An extensive parametric study was also carried out using these models in order to gain further insight in to the behaviour of composite beams with bolted and welded-stud connectors in composite steel–concrete beams. The outcome of the experimental and numerical analyses is satisfying and also contains design recommendations. It is strongly hoped that the findings of this study may provide an important basis and guidelines for designing and constructing more robust and sustainable composite beam systems in the future.

The ability to fold and unfold large sensor structures in space using hinges is important for space-based sensor technology. Tape spring hinges have become common in deployable space structures due to simplicity, repeatability and unique folding properties. The mechanical response of these hinges (moment-curvature, energy stored etc.) is important in ensuring safety, deployment accuracy as well as optimizing cost of the structure. In an effort to learn more about the folding and deployment properties, finite element software, Abaqus\u2122, was used to analyze a hinge using multidirectional bending. The analysis involved large deformation (rotation through 180 degrees), nonlinear geometric loading. In order to increase confidence in the analysis procedures, a study was conducted on how the type and size of elements affects stability and buckling of a simply-supported plate. In order to fold a tape spring, a specified length of the middle segment of the hinge was first flattened, so the initial curvature about the long axis of the hinge was removed. This minimizes the moment of inertia and hence stiffness allowing it to be folded. With the middle segment flattened, the hinge was subjected to opposite-sense bending about the hinges short axis (axis perpendicular to the length of the tape spring). In addition to providing the needed mechanical response, the study allowed investigation into the optimum method of folding a hinge. Energy stored during folding and unfolding could be evaluated which allows the designer to determine adequate passive damping to obtain necessary post-deployment stability and pointing accuracy.'

This thesis presents a solver to handle constrained-state-space ODEs. This solver locates the points where any of the states go outside of the constraining set, and then, transfers the control from the continuous time ODE to the function governing the behavior of the system on the boundaries of the constrained set. The main contribution of this solver is found simulating complex right-hand-sided ODEs for long periods of time.

The purpose of this paper is to investigate the nature and practical uses of Chebyshev polynomials. Chapter I gives recognition to mathematicians responsible for studies in this area. Chapter II enumerates several mathematical situations in which the polynomials naturally arise and suggests reasons for the pursuance of their study. Chapter III includes: Chebyshev polynomials as related to "best" polynomial approximation, Chebyshev series, and methods of producing polynomial approximations to continuous functions. Chapter IV discusses the use of Chebyshev polynomials to solve certain differential equations and Chebyshev-Gauss quadrature.

A 2D dry incompressible vorticity-stream function model is developed and used to investigate nonlinear buoyancy waves, especially internal solitary waves and related phenomena in the lower atmosphere. Using this model some essential properties of internal solitary waves have been successfully simulated. For the first time reversed recirculation within large amplitude solitary waves has been found. The existence of recirculation enables large amplitude solitary waves to trap air and transport it. Meanwhile, due to viscosity the trapped air continuously leaks out during the transport. The influences of surface friction and ambient vertical wind shear on solitary waves are also studied.

An interesting observation is made regarding the strongly heated experiments. The high drag state associated with the strong mountain wave and downslope windstorm control runs prevail but at a reduced level. The numerical experiments reveal that once a windstorm develops, a well-mixed boundary layer of modest depth (1.5 km) is unable to eliminate the high drag state completely. This result suggests that changes in the mean state are necessary for dissipation of the event.