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

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.

In this study, the mechanical properties of a fiber-reinforced cementitious composite (FRCC) were derived for specimens fabricated using two different methods of casting: conventional cast construction and pump-driven extrusion. Through the extrusion process, fibers are more likely to be oriented along the length of the member being cast and will therefore be more efficient since they are aligned parallel to the tensile stresses produced in flexure testing. The FRCC employed 0.5% and 1% polyvinyl alcohol (PVA) fiber reinforcement by volume. The flexural properties of FRCC were determined using four-point bend tests according to a modified ASTM C1609. Calculations included the modulus of rupture (MOR) and flexural toughness based on load-deflection curves. The fracture properties of FRCC were determined by using three-point bend tests on the same design but having notched beams using the two-parameter fracture model (TPFM). Calculations included the Mode I critical stress intensity factor (KIC), the critical crack tip opening displacement (CTODc), the strain energy release rate (GIC), and the total fracture energy (GF). The results show that enhanced ductility and post-peak behavior are achieved in concrete to which fibers have been added, as has been demonstrated in other studies, although this study further demonstrated how preferential fiber alignment produced via an extrusion can enhance fracture and flexural properties of cementitious composites. / Master of Science / Fiber-reinforced cementitious composite (FRCC) is a type of cementitious composite that contains fibers that are added to the mixture to improve its strength, durability, and ductility. One of the key factors of FRCC that affects its mechanical properties is the fiber alignment. Extrusion can be used as a method to preferentially align the fibers in order to maximize the benefit of fibers. Extruded FRCC can be pumped through a nozzle, making fiber alignment a convenient option for construction projects where traditional concrete placement methods would be difficult. One of the main benefits of aligning fibers in pump-extruded FRCC is that it can improve cementitious composites' fracture and flexural toughness. Fracture toughness refers to the ability of a material to resist crack propagation, while flexural toughness refers to its ability to withstand bending. By adding fibers to the mixture, the fibers act as reinforcement and help to distribute stress more evenly throughout the material, leading to increased strength and ductility. Furthermore, the alignment of fibers within the mixture also plays a critical role in the fracture and flexural strength of the material. Research has shown that when fibers are aligned in a specific direction, they can improve the tensile strength of the concrete and decrease the likelihood of crack propagation. This can be especially useful in structures that are exposed to seismic activity or long-lasting heavy loads. Overall, the use of pump extrusion-based method as a fiber alignment for FRCC can significantly improve the fracture and flexural strength of concrete. This makes it an attractive option for construction projects that require strong and durable members.