The research objective was to develop a new competitively priced, high strength macrosynthetic fiber for concrete reinforcement. Mechanical bond properties were examined through aligned and inclined pullout testing. Variables involved in optimizing these properties included materials, fiber cross section, and other changes made through manufacturing processes. In addition to extensive pullout testing, improvements to fiber properties were explored through tensile testing, creep testing, and fiber performance in concrete mixtures. Practical considerations were also made, such as manufacturing processes, cost, and workability. Properties of synthetic microfibers were also considered for use in engineered cementitious composites. Synthetic macrofibers containing PVDF demonstrated high bond strength in pullout testing. Fibers demonstrating the highest performance in FRC testing were those with additional mechanical anchorage such as fibrillation or embossment. EVA as an additive did not exhibit increased interfacial bond, but further research was recommended. Further research on deformed fibers containing PVDF was also recommended.

When a rope quickly transfers from a slack state to a taut state, a snapping action occurs and produces a large tensile force which is known as a snap load. Energy is dissipated during this snap load, and it is proposed to use synthetic fiber ropes as a type of passive earthquake damper in order to take advantage of this phenomenon. This thesis is the second phase of a multi-stage research project whose goal is to investigate and develop what will be known as Snapping-Cable Energy Dissipators (SCEDs). The experimental data that was collected in the Master'­s Thesis of Nicholas Pearson was organized and analyzed as a part of this research in order to evaluate the behavior of the ropes during the snapping action. Additional tests were also conducted for this project under more controlled conditions in order to better understand how the ropes change throughout a sequence of similar snap loadings and also to determine the amount of energy that is dissipated. The data from both projects was then used as input parameters for a mathematical model that was developed to characterize the behavior of the ropes during a snap load. This model will be utilized in subsequent research involving the finite element analysis of the seismic response of structural frames containing SCEDs. / Master of Science

Energy is lost when a rope transfers from a slack state to a taut state. This transfer is called a snap load and can be very violent. It is proposed to use synthetic fiber ropes as a type of passive control device in new or existing structures to mitigate seismic response. Experimental static and snap load (dynamic) tests were conducted on various synthetic fiber ropes. An eleven-foot-tall drop tower was built in the Virginia Tech Structures and Materials Laboratory in order to conduct these tests. Force and acceleration of the drop plate, which slides vertically within the drop tower, were measured with respect to time for all dynamic tests. Acceleration data was integrated using the trapezoidal or midpoint rule to obtain velocity and displacement values. Plots were made for each test in order to give a better representation of the results. These plots include representations of force and acceleration vs. time, force vs. absolute displacement, force vs. velocity, and force, acceleration, velocity, and displacement vs. time (during the initial taut phase only). Test results show that energy was dissipated in all of the dynamic drop tests, which was expected. Also, the displacement of each rope did not return to zero at the same time that the force returned to zero after the initial snap load. This proves that the ropes undergo some permanent elongation under load. The stiffness of each rope increased with continuous testing. As more tests are conducted on each rope, the strands are pulled tighter into the braided configuration, which causes the rope to become stiffer. / Master of Science

Movement of a bridge superstructure during a seismic event can result in damage to the bridge or even collapse of the span. An incapacitated bridge is a life-safety issue due directly to the damaged bridge and the possible loss of a life-line. A lost bridge can be expensive to repair at a time when a region's resources are most strained and a compromised commercial route could result in losses to the regional economy. This thesis investigates the use of Snapping-Cable Energy Dissipators (SCEDs) to restrain a simply supported single span bridge subjected to three-dimensional seismic loads. SCEDs are synthetic fiber ropes that undergo a slack to taut transition when loaded. Finite element models of six simply supported spans were developed in the commercial finite element program ABAQUS. Two seismic records of the 1940 Imperial Valley and 1994 Northridge earthquakes were scaled to 0.7g PGA and applied at the boundaries of the structure. The SCEDs were modeled as nonlinear springs with an initial slackness of 12.7mm. Comparisons of analyses without SCEDs were made to determine how one-dimensional, axial ground motion and three-dimensional ground motion affect bridge response. Analysis were then run to determine the effectiveness of the SCEDs at restraining bridge motion during strong ground motion. The SCEDs were found to be effective at restraining the spans during strong three-dimensional ground motion. / Master of Science

Blast resistance has recently become increasingly relevant for structural engineers. Blast loads are created by explosive devices that, upon detonation, create pressure loads that are much higher than most that a structure would ever experience. While there are many types of blast loads that are impossible to adequately prepare for, methods are presently being developed to mitigate these loads. This research investigates the possibility of using synthetic fiber ropes as a means of blast resistance. This is the third phase of a multi-stage research endeavor whose goal is to analyze Snapping-Cable Energy Dissipators (SCEDs) for reducing the effects of large-scale lateral loads. Finite element models of portal frames were developed using the commercial finite element program ABAQUS and dynamic models were run for varying blasts and frame systems. Blast pressures of 100, 2,000, and 4,000 psi were applied to a steel portal frame and comparisons were made between unbraced frames and frames braced with springs of different stiffnesses. Additional tests were run to examine the effects of strain rate dependent yield on the results of the models. Parallel research is being conducted on the specific material behavior of the synthetic fiber ropes so that the models developed for this research can be revised for a more accurate determination of the effects of the ropes on structural systems subjected to blast loads. / Master of Science

Fiber reinforcement is being widely used in concrete tunnel linings these days. Using fiber reinforcement can save not only cost, but also labor and time spent on construction. However, many owners hesitate to incorporate fiber reinforcement in tunnel lining due to lack of experience with and knowledge of the behavior of fiber reinforced concrete (FRC) In this study, fiber reinforced concrete was made with various kinds of fibers such as steel fiber, macro-synthetic fiber and hybrid fiber (a blend of macro-synthetic fiber and glass fiber). Many experimental tests were performed to investigate the compressive, flexural and shear behavior of fiber reinforced concrete. In addition to the structural capacity of FRC, the distribution of fiber reinforcement inside the concrete matrix was investigated. Test results of these experimental tests were thoroughly examined to compare and quantify the effects of fiber reinforcement. Next, the test results were used to generate axial force-bending moment interaction diagrams based on current design approaches. In addition, the current design approaches were modified to estimate the accurate and exact value of bending moment. Fiber reinforcement clearly improved the structural performance of tunnel lining. The post-peak flexural and shear strength was significantly influenced by the type and amount of fiber reinforcement. / text

El proyecto consiste en el estudio de prefactibilidad para la implementación de una planta industrial que produce monofilamento sintético estructural para concreto, producto usado para ser mezclado con el concreto y darle mayor resistencia a la flexión a la estructura y demás ventajas. El proyecto tendrá un periodo de análisis de 5 años. / The project consists of a pre-feasibility study for the implementation of an industrial plant that produces structural synthetic monofilament. The product is mixed with concrete to improve its flexural / Trabajo de investigación

Seismic design of guyed masts, commonly used in the broadcasting and telecommunications industries, has not been fully addressed in the United States. There is no specific design code, and only a limited amount of research has been reported on the subject. This research investigates the behavior of guyed masts incorporating synthetic ropes as guys, with a particular focus on the effect of snap loads on the mast behavior. This is the third phase of a multi-stage project aimed at analyzing the potential for Snapping-Cable Energy Dissipators (SCEDs) to minimize lateral response in structures. A finite element model of a 120-m-tall guyed mast was developed with the commercial program ABAQUS. The three-dimensional behavior of the mast was observed when subjected to two ground motion records: Northridge and El Centro. Three orthogonal earthquake components were input, two horizontal and one vertical. A series of parametric studies was conducted to determine the sensitivity of the response to guy pretension, which is a measure of the potential slackness in the guys during response. Additionally, the studies examined the effects of guy stiffness, mast properties, and directionality of input motion. Deflections, bending moments, guy tensions, and base shears were examined. The results were used to characterize the trends in the structural response of guyed masts. The level of slackness in the guys changed the behavior, and the lessons learned will be used to continue research on the application of SCEDs in structures. / Master of Science

[pt] O fenômeno de fluência em compósitos reforçados com fibras é particularmente importante quando são utilizadas macro fibras sintéticas, que devido ao seu baixo módulo de elasticidade, apresentam comportamento viscoelástico pronunciado mesmo em temperatura ambiente, o que pode levar a alterações no controle de fissuração ao longo do tempo. Testes de arrancamento são comumente usados para prever interações fibra-matriz e neste trabalho foram realizados para cargas de curto e longo prazo em três tipos de macro fibras sintéticas. Diferentes níveis de cargas de longo prazo (20, 30, 40 e 50 por cento da carga máxima de arrancamento em curta duração) e ângulos de orientação das fibras (15 graus celsius, 30 graus celsius e 45 graus celsius) em relação à direção da carga foram considerados para investigar a influência desses parâmetros na interação entre macro fibras sintéticas e matriz. Macro fibras com superfícies onduladas e maior módulo de elasticidade alcançaram maiores tensões de aderência e menores deformações por fluência. Em testes de curto prazo, imagens de microscopia óptica foram obtidas nas fibras arrancadas para correlacionar a degradação superficial das fibras com as curvas de tensão versus deformação. No arrancamento quase estático (curto prazo), foram observadas pequenas reduções na resistência ao arrancamento à medida que o ângulo foi aumentado para todas as fibras, além de uma intensa degradação de suas superfícies devido ao significativo efeito de polia. Em contraste, para os testes de longo prazo, foi observada uma redução da fluência com o aumento do ângulo de inclinação da fibra causada pela redução da fluência da fibra devido ao carregamento não axial e componentes de força adicionais produzidos pelo desvio da força axial. O modelo viscoelástico de Burgers foi aplicado e apresentou boa concordância com as curvas de fluência experimentais, consistindo, portanto, em uma alternativa promissora para modelar o comportamento de longo prazo de fibras individuais. Imagens de microtomografia e microscopia eletrônica de varredura mostraram que uma parte da deformação em tração, sob carga sustentada, pode ser atribuída à fluência da própria fibra, tornando desafiador estimar a fluência deste tipo de compósito, dada a considerável variabilidade de configurações de fibra. / [en] The creep phenomenon in fiber-reinforced composites is particularly important when macro synthetic fibers are used, due to their low modulus of elasticity, exhibit pronounced viscoelastic behavior even at room temperature, which can lead to changes in the cracking control over time. Pullout tests are commonly used to predict fiber–matrix interactions and in this work were conducted for short- and long-term on three types of polymeric macro fibers. Different levels of long-term loads (20, 30, 40 and 50 percent of the maximum short-term pullout load) and fiber orientation angles (15 degrees celsius, 30 degrees celsius, and 45 degrees celsius) with respect to the direction of the load were considered to investigate the influence of these parameters on the interaction between macro synthetic fibers and matrix. Macro fibers with crimped surfaces and higher modulus of elasticity achieved higher bond stresses and lower creep deformations. In short-term tests, optical microscopy images were obtained on the pulled-out fibers to correlate the surface degradation of the fibers with the stress versus strain curves. In quasi-static pullout (short-term), small reductions in pullout strength were observed for all fibers and angles, in addition to an intensive degradation of their surfaces owing to the significant snubbing effect of this type of fiber. In contrast, for the long-term tests, a creep reduction was observed with increasing fiber inclination angle caused by the creep reduction of the fiber due to non-axial loading and additional force components produced by the deviation of the axial force. The Burgers viscoelastic model was applied and showed good agreement with the experimental creep curves, therefore consisting of a promising alternative for modeling the long-term behavior of individual fibers. Microtomography and scanning electron microscopy images showed that a large portion of the strain in tension, under sustained load, can be attributed to the creep of the fiber itself, thus making it challenging to estimate the creep of this type of composite, given the considerable variability of fiber configurations.

Mikroplast är ett begrepp som förekommer allt mer frekvent i media och medför stor förvirring kring var det kommer ifrån och varför det är skadligt. Naturvårdsverket har listat de sju största faktorerna till emission av mikroplast i Sverige, där hushållstvätt av syntetfiber är en utav dem. Mikroplast är små plastfragment (1 nm- 5 mm) och härstammar inte bara från syntetfiber, utan från bland annat däckslitage, allmän nedskräpning och fiskeverktyg. Vid hushållstvätt sprids partiklarna via avloppsvattnet, genom reningsverk och hamnar till slut i havet där de drar till sig miljöfarliga kemikalier och skadar vattenlevande organismer. Den här studien utreder textilföretags miljökommunikation angående mikroplast gentemot kund samt vad det finns för råd och direktiv från organisationer och myndigheter för textilföretag att tillgå vid dess generering av mikroplast. Studiens ambition är att kunna förmedla samlade riktlinjer till textilföretag som kan appliceras till deras verksamhet. Studien stöds utav RISE IVF och MinShed projektet och kommer genomföras med hjälp av litteratur-, enkät-, och intervjustudier. Resultatet som tagits fram genom uppsatsen visar att textilföretag generellt inte kommunicerar mikroplast gentemot kund. Det här beror på den, än så länge, bristfällig forskning som finns tillgänglig angående emission av mikroplast. Textilföretag upplever att de inte har tillräckligt med information för att ta långsiktiga beslut som kan förbättra dess hantering av mikroplast. Avsaknaden av standardiserade testmetoder över hur mycket olika syntetfiber fäller är det som textilföretag upplever saknas. Resultatet visar också att organisationer och myndigheter överlag inte ger några råd och direktiv till specifikt textilföretag. Utifrån de resultat som presenteras från det underlag som grundat sig från litteratur-, enkät-, och intervjustudier, kan författarna dra slutsatsen att rapporten inte kommer bidra med rekommendationer till textilföretag. Författarna uppmanar till vidare forskning inom ämnet, främst angående utveckling av filter i tvättmaskiner, som skulle kunna hindra mikroplast att spridas ut i havsmiljön via avloppsvattnet. / Microplastic waste is something that is featured more and more frequently in media today. There is a lot of confusion, due to the focus in the media, on what microplastic waste actually is and in what way it is harmful to the environment. The Environmental Protection Agency has listed the seven biggest sources to microplastic shedding and it shows that household laundry of synthetic fibers is one of them. Microplastic waste, or microplastics, are small plastic fragments (1 nm- 5 mm) and originate not only from synthetic fibers, but from tire wear, general plastic waste and fishing tools. During household laundry, the synthetic fibers shed microplastic that travels through the wastewater and sewage treatment plants before it finally ends up in the ocean where they have the potential to attract hazardous chemicals and damage aquatic organisms.    This study examines textile companies environmental communication regarding microplastics towards their customer and what kind of guidelines different organizations, institutes and authorities offer to textile companies regarding their generation of microplastics. The ambition of the study is to gather overall guidelines to textile companies that can be applied to their businesses. The study is supported by RISE IVF and the MinShed project and has been accomplished by literature-, questionnaire-, and interview studies. The outcome of the study shows that textile companies generally do not communicate about microplastics to their customer. This is due to the, so far, inadequate research regarding microplastic shedding. Textile companies experience that they do not have enough information to make long-term decisions that can improve their microplastic management, since there is no standardized test methods for fabrics available. The result also shows that organizations and authorities generally do not provide guidelines specific to textile companies. Based on the result from the study, the writers will not accomplish to gather guidelines to textile companies regarding microplastic management. The writers request further research on microplastics, primarily regarding the development of filters in washing machines, which could prevent microplastics from spreading out into the marine environment via the wastewater.