abstract: Civil infrastructures are susceptible to damage under the events of natural or manmade disasters. Over the last two decades, the use of emerging engineering materials, such as the fiber-reinforced plastics (FRPs), in structural retrofitting have gained significant popularity. However, due to their inherent brittleness and lack of energy dissipation, undesirable failure modes of the FRP-retrofitted systems, such as sudden laminate fracture and debonding, have been frequently observed. In this light, a Carbon-fiber reinforced Hybrid-polymeric Matrix Composite (or CHMC) was developed to provide a superior, yet affordable, solution for infrastructure damage mitigation and protection. The microstructural and micromechanical characteristics of the CHMC was investigated using scanning electron microscopy (SEM) and nanoindentation technique. The mechanical performance, such as damping, was identified using free and forced vibration tests. A simplified analytical model based on micromechanics was developed to predict the laminate stiffness using the modulus profile tested by the nanoindentation. The prediction results were verified by the flexural modulus calculated from the vibration tests. The feasibility of using CHMC to retrofit damaged structural systems was investigated via a series of structural component level tests. The effectiveness of using CHMC versus conventional carbon-fiber reinforced epoxy (CF/ epoxy) to retrofit notch damaged steel beams were tested. The comparison of the test results indicated the superior deformation capacity of the CHMC retrofitted beams. The full field strain distributions near the critical notch tip region were experimentally determined by the digital imaging correlation (DIC), and the results matched well with the finite element analysis (FEA) results. In the second series of tests, the application of CHMC was expanded to retrofit the full-scale fatigue-damaged concrete-encased steel (or SRC) girders. Similar to the notched steel beam tests, the CHMC retrofitted SRC girders exhibited substantially better post-peak load ductility than that of CF/ epoxy retrofitted girder. Lastly, a quasi-static push over test on the CHMC retrofitted reinforced concrete shear wall further highlighted the CHMC's capability of enhancing the deformation and energy dissipating potential of the damaged civil infrastructure systems. Analytical and numerical models were developed to assist the retrofitting design using the newly developed CHMC material. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2013

Cette thèse traite quatre sujets différents de la théorie des espaces de Banach: Le premier est une caractérisation de la propriété de Radon-Nikodym en utilisant la notion du jeu des points et tranches: Le deuxième est une évaluation de l'indice de dentabilité préfaible des espaces C(K) où K est un compact du hauteur dénombrable: Le troisième est un renormage des espaces non séparables qui est simultanément LUC, lisse et approximable par des normes d'une lissité plus élevée. Le quatrième est une approche par le théorème de Baire aux principes variationnels paramétriques. La thèse commence par une introduction qui examine le contexte de ces résultats. / The thesis deals with four topics in the theory of Banach spaces. The first of them is a characterization of the Radon-Nikodym property using the notion of point-slice games. The second is a computation of the w* dentability index of the spaces C(K), where K is a compact of countable height. The third is a renorming result in nonseparable spaces, producing norms which are differentiable, LUR and approximated by norms of higher smoothness. The fourth topic is a Baire cathegory approach to parametric smooth variational principles. The thesis features an introduction which surveys the background of these results.