The present study reviews applications of FRP materials joined by structural adhesives in civil engineering. FE analysis with mix-mode cohesive zone material model (CZM) was used to analyze stresses induced in two structural adhesives joining dissimilar materials (concrete GFRP-CFRP) of the hybrid-composite unit. The predicted failure loads, displacements and deformation by the 3-D non-linear FE analysis in the present study are in good agreement with the experimental results of the hybrid-composite unit reported by Deskovic et al. (1995). The contact analysis revealed a complex 3-D state of stress in the bondlines of both structural adhesives. It is concluded that higher joint strength is expected when a ductile adhesive is used. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

This study presents the experimental results of nine full-scale lap spliced glass-fiber reinforced polymer (GFRP) reinforced concrete (RC) columns, and one additional reference steel-RC column with lap splices, under axial and cyclic-reversed loads. The test parameters included type of reinforcement, lap splice length of longitudinal reinforcement, transverse reinforcement spacing, and the effect of using steel fiber-reinforced concrete (SFRC). Test results indicated that a splice length of 60 times the diameter of the longitudinal column bar was adequate in transferring the full bond forces along the splice length and were able to maintain the lateral load carrying capacity when subjected to higher levels of axial loads and drift ratios. In addition, lap spliced GFRP-RC columns with closely spaced transverse reinforcement achieved high levels of deformability. Furthermore, the use of SFRC in columns with inadequate splice increased the peak lateral strength and the energy dissipation of the specimens. / February 2017

Innovative new flooring systems utilising lightweight fibre reinforced polymer composite materials may have the significant potential to offer both economic and performance benefits for infrastructure asset owners compared to conventional concrete and steel systems. Over recent years, a range of prototype floor systems using fibre reinforced polymer composites have been developed by researchers at the University of Southern Queensland. However before such structural systems can be widely adopted by industries, fundamental understanding of their behaviour must be improved. Such work will allow for the development of new design and analysis procedures which will enable engineers to efficiently and accurately design and analyse such structures. This dissertation presents an investigation into a new two-way fibre reinforced composite floor slab system. The proposed new two-way slab system is, in essence, a sandwich structure with an innovative hollow core made from a castable particulate filled resin system. The key focus of this dissertation is the development of a new analysis tool to analyse the two-way fibre reinforced composite slab and facilitate subsequent parametric studies into slab configurations for concept refinement. The detailed 3D finite element analyses and experimental investigations are performed to verify the new analysis tool, and provide more detailed insight into the structural behaviour of this new two-way fibre reinforced composite slab. Comparisons with detailed 3D FEA and experiments illustrate that the simplified analysis tool is capable of providing sufficient accuracy for the preliminary analysis of a slab structure. Moreover, the 3D finite element analyses agree well with the experiments, and it is concluded that the behavioural responses of the proposed new slab structure can be reliably predicted. The experimental results show that this new slab concept exhibits quite a robust static behaviour and is likely to have a robust fatigue performance.

Ο σκοπός αυτής της διπλωματικής εργασίας είναι η σύγκριση της αποτελεσματικότητας της ενίσχυσης, στοιχείων από φέρουσα τοιχοποιία, με μανδύες συνθέτων υλικών, οι οποίοι αποτελούνταν από στρώσεις ανθρακοϋφάσματος, με οργανική ή ανόργανη μήτρα και με τοποθέτηση ράβδων οπλισμού, από ανθρακονήματα, μέσα στους συνεχείς αρμούς της τοιχοποιίας. Αρχικά δίνονται μορφολογικά και γενικά τεχνικά χαρακτηριστικά. Γίνεται μια σύντομη ιστορική ανασκόπηση για την τοιχοποιία και ακολουθεί ο διαχωρισμός της σε βασικές κατηγορίες. Αναφέρονται οι πρώτες ύλες των τεχνητών λιθοσωμάτων και η διαδικασία παραγωγής τους και στη συνέχεια σημειώνονται τα βασικά είδη τους, με τις συνήθεις διαστάσεις και οι τεχνικές προδιαγραφές τους. Γίνεται ακόμα αναφορά στις κατηγορίες και στις ιδιότητες των κονιαμάτων και των επιχρισμάτων που χρησιμοποιούνται. Ακολουθεί μια περίληψη της μηχανικής της τοιχοποιίας. Περιγράφεται η λειτουργία της άοπλης τοιχοποιίας και ο προσδιορισμός της αντοχής της, υπό θλιπτικά, καμπτικά και διατμητικά φορτία, κατά τον Ευρωκώδικα 6 (EC6) και Τάσιο. Περιγράφονται επίσης τα ελαστικά χαρακτηριστικά της τοιχοποιίας και ο τρόπος, με τον οποίο αυτή συμπεριφέρεται υπό οριζόντια πλευρική φόρτιση, ενώ φέρει θλιπτικά φορτία. Στη συνέχεια γίνεται περιγραφή των ενισχύσεων κατασκευών με σύνθετα υλικά. Κατηγοριοποιούνται τα σύνθετα υλικά και δίνονται οι ιδιότητες των συνθέτων ινο-πλισμένων υλικών. Αναφέρονται εν συντομία οι ιδιότητες των υλικών, ινών και ρητινών, που χρησιμοποιούνται συνήθως για την κατασκευή ινοπλισμένων πολυμερών. Ακόμα αναφέρονται τα βασικά συστήματα ενίσχυσης και οι ιδιότητες των συνθέτων υλικών. Ακολουθεί η μικρομηχανική των υλικών αυτών και οι επιπτώσεις, των περιβαλλοντικών συνθηκών, στην ανθεκτικότητά τους. Επίσης, γίνεται μια περιληπτική αναφορά στις τεχνικές ενισχύσεων δομικών στοιχείων με σύνθετα υλικά. Έπεται μια σύντομη αναφορά στις βάσεις σχεδιασμού ενισχύσεων με σύνθετα υλικά. Δίνονται οι καταστατικοί νόμοι των υλικών για οριακή κατάσταση αντοχής, τόσο για πλήρη συνεργασία όσο και για αποκόλληση του συνθέτου υλικού από την κατασκευή, και για οριακή κατάσταση λειτουργικότητας. Επίσης σχολιάζεται και το θέμα της συνάφειας των συνθέτων υλικών με το υπόστρωμα (τοιχοποιία). Ακολούθως περιγράφονται τα υλικά κατασκευής και ενίσχυσης, τα πειραματικά δοκίμια και δίνονται οι μηχανικές τους ιδιότητες. Ακόμα γίνεται περιγραφή των ειδών των δοκιμίων, που δημιουργήθηκαν, της διαδικασίας ενισχύσεώς τους, σύμφωνα με τους τρόπους που είχαν αποφασιστεί, δηλαδή με κατασκευή μανδυών και με τοποθέτηση ράβδων οπλισμού από σύνθετα υλικά. Επίσης περιγράφονται εν συντομία ο μηχανικός εργαστηριακός εξοπλισμός, που χρησιμοποιήθηκε για την εκτέλεση των πειραματικών διαδικασιών. Στην συνέχεια γίνεται αναλυτική προσομοίωση για κάθε είδος δοκιμίου και ενίσχυσης, από όπου εξάγεται και η θεωρητική τιμή της αντοχής τους, και περιγραφή της πειραματική διαδικασίας, που ακολούθησε για τον έλεγχό τους. Ακολούθως, γίνεται σύγκριση μεταξύ των τρόπων ενίσχυσης και αναφορά των σχετικών πλεονεκτημάτων και τα μειονεκτημάτων τους, ανά κατηγορία δοκιμίων. Τέλος, δίνονται τα συμπεράσματα της εργασίας, που συνοπτικά είναι ότι η χρήση α-νόργανης μήτρας για την κατασκευή μανδυών προσφέρει, με σχετική μείωση της αντοχής, μεγαλύτερη παραμορφωσιμότητα και ικανότητα απορρόφησης ενέργειας και ότι η ενίσχυση, με τοποθέτηση ράβδων ανθρακονήματος, μέσα στους συνεχείς αρμούς της τοιχοποιίας, είναι επισφαλής, λόγω της μη ικανοποιητικής συνάφειάς τους με το συνδετικό κονίαμα, αποτελέσματα, τα οποία μπορούν να χρησιμοποιηθούν για την καλύτερη διαστασιολόγηση των ενισχύσεων με σύνθετα υλικά. Επίσης αναφέρονται κάποια θέματα που χρήζουν περαιτέρω μελέτης, όπως η τοποθέτηση των ράβδων ανθρακονημάτων σε άλλες θέσεις και διευθύνσεις, το απαιτούμενο ποσοστό ινών και η πιθανή τροποποίηση των πειραματικών διατάξεων, ώστε να πραγματοποιηθεί ακριβέστερη προσομοίωση των πραγματικών στοιχείων και φορτίσεων, μιας κατασκευής. / The purpose of this study is the comparison between the use of fibre-reinforced polymers (FRP) as strengthening materials for masonry walls with jackets of polymeric matrix (organic and inorganic) using carbon fabrics and strips (into the constant joints of masonry). First of all, is discribed the history of masorny and its categories. Then, are mentioned the first materials for bricks, the procedure for their produce and their sizes. Also, are mentioned the categories of mortar and plaster. Moreover, is discribed the mechanics of masonry according the Eurocode 6(EC6) and the professor Tasios. Furthermore, are reported the categories of composite materials and their qualities. Also, is annotated the connection between the composite materials and the masonry (substratum). Apart from this, are described the materials that were used to form and reinforce elements of masonry wall. Also, are described the types of elements of masonry wall, that were built, the procedure for their reinforcement and the mechanical equipment of the laboratory, where expirements took place. Moreover, are annotated the analytical model for every type of masonry element, from where theoritical values were taken and the experimental procedure. Furthermore, is presenced the comparison between every type of reinforcment and their advantages or disadvantages. Finally, are decribed subjects for future usage and results of this study.

Today¿s engineers spend an increasing proportion of their time on the maintenance and retrofitting of existing structures. Many of these structures were designed for a purpose totally different from that for which they are now employed. The use of buildings has changed over the last few decades especially during the commercial boom in the 1990s and bridge structures are taking on more and more loads as traffic on the roads continues to rise dramatically.

Within this research, factors affecting the orientation of injection molded long fiber composites in an end-gated plaque were investigated. Matrix viscosity was found to have a small effect on fiber orientation. The impact matrix viscosity had on orientation was dependent on fiber loading. At lower fiber loadings, the higher viscosity material had a more asymmetric orientation profile throughout the samples and less of a shell-core-shell orientation. At higher fiber loadings, there were few differences in orientation due to matrix viscosity. Fiber concentration was found to have a larger influence on fiber orientation than matrix viscosity. Increased fiber concentration led to a lower degree of flow alignment and a broader core region at all locations examined, following the trend previously reported for short fiber composites. The orientations of three different fiber length distributions of glass fiber (GF) were compared. The longer fibers in the fiber length distribution were shown to have a disproportionate effect on orientation, with weight average aspect ratio being better than number average aspect ratio at indicating if the GF and CF samples orientated comparably. To improve properties transverse to the main flow direction, the super critical carbon dioxide aided deagglomeration of multi-walled carbon nanotubes (CNTs) was used to create injection molded multiscale composites with CNT, CF, and polypropylene. The addition of CNTs greatly improved the tensile and electrical properties of the composites compared to those without CNTs. The degree of improvement from adding CNTs was found to be dependent on CF concentration, indicating that the CNTs were most likely interacting with the CF and not the polymer. A CNT concentration of 1 wt% with a tenfold degree of expansion at 40 wt% CF proved to be optimum. A large improvement in the tensile properties transverse to the flow direction was found implying that the CNTs were not highly flow aligned. Tensile and electrical properties began to fall off at higher CNT loadings and degrees of expansion indicating the importance of obtaining a good dispersion of CNTs in the part. / Ph. D.

Master of Science / Department of Architectural Engineering and Construction Science / Kimberly W. Kramer / Pultruded fiber reinforced polymer (FRP) shapes are gaining popularity in the construction industry. Pultruded FRP profiles introduce a new world of construction that could prove to be a viable option to traditional structural materials. The use of pultruded FRP profiles in structures is discussed in this report. First a brief history of FRPs and their applications are addressed before explaining in detail the two main components of FRP; fibers and resin. The manufacturing process known as pultrusion and how two separate materials become one structural member is examined. As a result of pultrusion, engineers and designers can create structural profiles in customizable shapes, sizes, and strengths to suit any project and price. Theoretically, a pultruded FRP profile can be customized to different strengths within the geometrical and material bounds of the profile; however, many manufacturers publish data regarding mechanical and thermal properties along with allowable loads for their nominal profiles. Currently, there are no governing codes or guidelines for pultruded FRPs but there are design manuals and handbooks published by various committees and manufacturers so the design of pultruded FRP profiles is discussed. Ultimate and serviceability limit states are design concerns that engineers always deal with but concerns of heat or fire, chemical or corrosion, and moisture affect pultruded FRPs differently than steel or wood. Pultruded FRPs pose interesting design concerns because increased customizability and workability means the member can be tailored to meet the needs for that project but that would counter the benefit of mass-produced nominal sizes. A lack of uniform codes and standards inhibits the growth of the pultrusion industry in the United States but codes developed in Europe along with the development of specialized agencies and organizations could help gain a foothold. Lastly, a set of beams varying in length and load exhibit a side-by-side comparison to examine how pultruded FRPs match up next to traditional building materials. Although wood, steel, and reinforced concrete have been the preferred materials of construction, pultruded FRP structural shapes are gaining popularity for its economical and physical advantages, and advances in manufacturing and technology stand to usher in the widespread use of pultruded FRP profiles.

Montmorillonite reinforced polymers are a new development in the area of nanocomposite materials. Since reinforcement of epoxy is important to the development of high strength adhesives and composite matrices, the introduction of montmorillonite to epoxy is of interest. Compositional effects on epoxy reactivity, on molecular relaxation, and on mechanical properties were investigated. Change in reactivity was determined by Differential Scanning Calorimetry. Tensile properties at room temperature indicated improved modulus and retention of strength of the epoxy matrix but a decreased elongation to failure. Depression of dry nanocomposite glass transition was observed for nanocomposites beyond 5% by weight montmorillonite. Samples that were saturated with water showed lower moduli due to the epoxy matrix. The greatest moisture absorption rate was found at 7%, the least at 3%.

Na busca de materiais de baixa densidade, alta resistência e baixo custo, o processo de Filament Winding, ou Enrolamento Filamentar, surge como uma das opções de processo automatizado para a fabricação de componentes em materiais compósitos reforçados por fibras (FRP – Fiber Reinforced Polymers). Tendo uma ampla aplicação estrutural, o tipo de fibra, o tipo de matriz, a orientação das fibras, as camadas de reforço, o mandril a ser utilizado e a otimização da trajetória de deposição das fibras são características essenciais para obtenção de uma peça com as características desejadas no processo. Dentre as necessidades para a utilização deste processo, exerce um papel de destacada influência a geração dos dados da trajetória de deposição da fibra, bem como a geração dos dados operacionais do processo. Este trabalho tem por objetivos desenvolver um programa para a geração destes dados, bem como os dispositivos necessários para a execução do processo de Filament Winding em torno CNC comercial. Os dados das trajetórias são gerados de modo integrado ao sistema CAD, representados por meio dos ângulos das trajetórias, e são alimentados em um programa computacional desenvolvido para este fim, que gera o código CN para a fabricação da peça no equipamento. Para a execução deste código na máquina CNC, foram desenvolvidos sistema de fixação do mandril e alimentador da fibra (incluindo tensionador) que possibilitam a execução do processo neste tipo de equipamento. Todo o sistema desenvolvido foi implementado e utilizado para a confecção de tubos com diferentes trajetórias de preenchimento, validando o sistema computacional e o processo desenvolvido. / In the search of low density, high strength and low cost materials, Filament Winding seems to be an option of automated process to manufacture components in Composite Materials Reinforced by Fibers (FRP – Fiber Reinforced Polymers). Due to its large application in structural engineering, aspects such as fibers, matrices, fiber paths and laminate sequence are essential characteristics to obtain the desired final part. Among the requirements to use the Filament Winding Process, the definition of the fiber paths as well as the laminate sequence play fundamental roles in order to achieve the optimum structural performance of the composite part. This work aims to develop the necessary program to generate this data and devices required for the implementation of Filament Winding process in a commercial CNC machine tool. The data of the trajectories are generated in the CAD system, represented by the angles of the trajectories, and are fed in a computer program developed for this purpose, which generates the NC code for the manufacture of the part in the machine. In order to carried out this code in the CNC machine there were developed mandrel fixation system and fiber feeder (including tensioner were deverloped) that enable to wind the part in this type of equipment. The system developed has been implemented and used for the manufacture of tube parts with different fiber paths, validating the integrated system and the process developed.

Na busca de materiais de baixa densidade, alta resistência e baixo custo, o processo de Filament Winding, ou Enrolamento Filamentar, surge como uma das opções de processo automatizado para a fabricação de componentes em materiais compósitos reforçados por fibras (FRP – Fiber Reinforced Polymers). Tendo uma ampla aplicação estrutural, o tipo de fibra, o tipo de matriz, a orientação das fibras, as camadas de reforço, o mandril a ser utilizado e a otimização da trajetória de deposição das fibras são características essenciais para obtenção de uma peça com as características desejadas no processo. Dentre as necessidades para a utilização deste processo, exerce um papel de destacada influência a geração dos dados da trajetória de deposição da fibra, bem como a geração dos dados operacionais do processo. Este trabalho tem por objetivos desenvolver um programa para a geração destes dados, bem como os dispositivos necessários para a execução do processo de Filament Winding em torno CNC comercial. Os dados das trajetórias são gerados de modo integrado ao sistema CAD, representados por meio dos ângulos das trajetórias, e são alimentados em um programa computacional desenvolvido para este fim, que gera o código CN para a fabricação da peça no equipamento. Para a execução deste código na máquina CNC, foram desenvolvidos sistema de fixação do mandril e alimentador da fibra (incluindo tensionador) que possibilitam a execução do processo neste tipo de equipamento. Todo o sistema desenvolvido foi implementado e utilizado para a confecção de tubos com diferentes trajetórias de preenchimento, validando o sistema computacional e o processo desenvolvido. / In the search of low density, high strength and low cost materials, Filament Winding seems to be an option of automated process to manufacture components in Composite Materials Reinforced by Fibers (FRP – Fiber Reinforced Polymers). Due to its large application in structural engineering, aspects such as fibers, matrices, fiber paths and laminate sequence are essential characteristics to obtain the desired final part. Among the requirements to use the Filament Winding Process, the definition of the fiber paths as well as the laminate sequence play fundamental roles in order to achieve the optimum structural performance of the composite part. This work aims to develop the necessary program to generate this data and devices required for the implementation of Filament Winding process in a commercial CNC machine tool. The data of the trajectories are generated in the CAD system, represented by the angles of the trajectories, and are fed in a computer program developed for this purpose, which generates the NC code for the manufacture of the part in the machine. In order to carried out this code in the CNC machine there were developed mandrel fixation system and fiber feeder (including tensioner were deverloped) that enable to wind the part in this type of equipment. The system developed has been implemented and used for the manufacture of tube parts with different fiber paths, validating the integrated system and the process developed.