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Full Text, Thesis (PhD Doctorate), Doctor of Philosophy (PhD), School of Eng & Built Env, Science, Environment, Engineering and Technology, In the current study, the major aim was to develop computationally-effective numerical procedures with the capability of modelling the thermal and mechanical response of fibre-reinforced composites. The attempt was made with a focus on the applicability of the procedures to a variety of synthetic and natural fibres with various geometrical characteristics so that a materialindependent framework is developed. The work is divided into three main stages: developing methodologies, investigating the performance of the available analytical tools, and extending the material models by numerical techniques. The finite element computational framework was used and a library of general-purpose subroutines was developed that encompassed the methodologies. Then, finite element prototypes were challenged through a variety of thermal and mechanical analyses to set up the interaction between micro- and macro-scales. Representative volume elements (RVEs) were created for a variety of short/long and aligned/randomly-oriented fibres in thermal analyses. Fibre orientation tensors were used to carry out clustering and spectral analyses in order to characterise the morphology of the heterogeneities. According to the results of sensitivity analyses, although spectral analysis seems to be less sensitive to local variation of fibre direction, it correlates better with the effective properties. Furthermore, the element elimination technique was used to indirectly model the progression of damage. This technique was used in both discrete fibre modelling and homogenised elements. It was shown that by following the latter case, mesh-independent results could be obtained. Moreover, natural fibre-reinforced composites were modelled using discrete fibre elements and a new strength-updating scheme was proposed and implemented. The numerical results showed the detrimental effect of considering length-dependent strength properties in computational modelling. Namely, the strength of fibres must be updat