During a risk assessment undertaken in a factory dealing with fiber reinforced plastic products in the northwestern part of Peninsular Malaysia, styrene was identified as the most potential hazard in the factory. It was therefore chosen to focus the rest of the risk assessment on this chemical. The purpose of this risk assessment was to find out which negative health effects styrene could have on the factory workers, especially on the laminators who are dealing daily with styrene at a close range during lamination through hand lay-up. This was investigated theoretically through a literature research and practically through measurements of styrene in the air in the factory. The styrene doses were measured on two occasions at several distances away from the potential sources. These measurements were high compared with dose-response relationships found in the literature and various national occupational exposure limit values with regards to styrene. The calculated risk quotient (RQ) was also greater than one and it is therefore likely that styrene has negative health effects on the workers in the factory. The various negative health effects identified in the literature were then included in a risk matrix were they were ranked according to the probability that they would have a negative effect on the factory workers. Hearing- and colourvision effects were ranked as very likely, effects on the central nervous system and the respiratory system as well as livertoxicity were classified as likely and genotoxicity was ranked as a possible negative health effect. In the future it would be interesting to talk to the current laminators and do health check-ups to see if they are suffering from any of the suggested negative health effects. It would also be interesting to follow them on a longterm basis to see if their health is changing and if this can be linked to the styrene handling in the factory. / Vid en riskbedömning i en fabrik i nordvästra Malaysia identifierades styren som den största hälsofaran för fabriksarbetarna, framförallt laminerarna eftersom de ofta hanterar styren på nära håll. Det valdes därför att fokusera den resterande riskbedömningen just på styren och dess möjliga negativa hälsoeffekter. Syftet med studien var att ta reda på om styren kan ha en negativ effekt på fabriksarbetarnas hälsa. Detta undersöktes teoretiskt genom en litteraturstudie och praktiskt genom mätningar av styrenhalten i fabriken. Vid två tillfällen mättes styrenhalten i fabriken. De uppmätta halterna jämfördes sedan med de dos-responssamband som funnits vid litteraturstudien, samt med olika nationella hygieniska gränsvärden för styren. De uppmätta värdena visade sig vara höga jämfört med de funna i litteraturen. Det bidrog tillsammans med den beräknade riskkvoten som visade sig vara större än ett, till slutsatsen att styren har en negativ effekt på fabriksarbetarnas hälsa. De möjliga negativa hälsoeffekter som identifierats i litteraturen rangordnas med hjälp av en riskmatris enligt sannolikheten att de skulle utgjöra en risk för arbetarna i fabriken. Effekter på hörseln och färgseendet ansågs vara mycket sannolikt, effekter på centrala nervsystemet (CNS) och levern samt irritation av andningssystemet ansågs sannolika och att styren skulle vara genotoxiskt ansågs möjligt. Övriga hälsoeffekter ansågs osannolika eller mycket osannolika. I framtida studier skulle det vara intressant att diskutera med de nuvarande laminerarna och undersöka dem medicinskt för att se om de har påverkats utav några av de förväntade hälsoeffekterna. Det vore också intressant att följa dessa arbetare under en längre tid för att se om deras hälsa ändras på något sätt som skulle kunna kopplas till styrenhanteringen i fabriken.

The use of fiber reinforced polymers (FRP's) for structural repair or retrofit has increased significantly in the last decade, with adoption for civil infrastructure occurring only in the last 20 years. These products are most often used to increase the capacity of damaged or deteriorated structures. Much research has been performed in the arena of testing of various FRP's bonded to both concrete and masonry substrates, the majority of which focusing on three areas; flexural strengthening, in-plane shear strengthening, and mechanical anchoring. Anchorage is commonly the limiting factor in the application of FRP's, due to the inability of the edge of the polymer matrix to reliably extend beyond a point of zero-interfacial stress. Where interfacial stresses exist and the FRP is terminated localized disbondment often occurs, these localized failures then propagate across the entire bond of the structural system. Various mechanical termination details have been tested to mitigate the potential failure modes near the ends of the fabric. There, however, has been very limited research performed on the behavior of dowels which are installed parallel to the FRP fabric and splayed onto the FRP fabric matrix. In this research the mechanical properties of carbon fiber reinforced polymer (CFRP) dowels with a parallel orientation to uniaxial carbon fabric are experimentally tested to determine the tensile capacity of "dowel to splay" CFRP connections and to discover any dominant failure modes.

No description available.

This study presents a combined viscoelastic (VE)-viscoplastic (VP) analysis for Fiber Reinforced Polymer (FRP) composites subject to simultaneous mechanical load and conduction of heat. The studied FRP composites consist of unidirectional fibers, which are considered as linearly elastic with regards to their mechanical response, and isotropic polymeric matrix, which shows viscoelastic-viscoplastic response under various stresses and temperatures. Due to the viscoelastic and viscoplastic behavior of the polymeric matrix, the overall FRP composites exhibit a combined time-dependent and inelastic behavior. A simplified micromechanical model, consisting of a unit-cell with four fiber and matrix subcells, is formulated to homogenize the overall heat conduction and viscoelastic-viscoplastic responses of the FRP composites. The micromechanical model is compatible with a displacement based finite element (FE) and is implemented at the Gaussian integration points within the continuum finite elements, which is useful for analyzing the overall time-dependent response of FRP composite structures under various boundary conditions. The Schapery nonlinear integral model combined with the Perzyna viscoplastic model is used to describe the viscoelastic-viscoplastic response of the polymer constituents. An integrated time integration algorithm is formulated at the micromechanics level in order to solve the nonlinear viscoelastic-viscoplastic constitutive model at the matrix subcells and obtain the overall nonlinear response of the FRP. The viscoelastic-viscoplastic micromechanical model is validated usingexperimental data on off-axis glass/epoxy FRP composites available in literature. The overall response of the FRP composites determined from the simplified micromechanical model is also compared with the ones generated from microstructures of FRP with various fiber arrangements dispersed in homogeneous polymer matrix. The microstructural models of the FRP with detailed fiber arrangements are generated using FE. The effects of thermal stresses, due to the mismatches in the coefficient of thermal expansions of the fibers and polymeric matrix, and stress concentrations/discontinuities near the fiber and matrix interfaces on the overall thermo-mechanical deformation of FRP composites are studied using the two micromechanical models discussed above. Finally, an example of structural analysis is performed on a polymeric smart sandwich composite beam, having FRP skins and polymeric foam core with piezoelectric sensors integrated to the FRP skins, undergoing three point bending at an elevated temperature. The creep displacement is compared to experimental data available in literature.

Thesis (M.Tech.:Mechanical Engineering)-Dept. of Mechanical Engineering, Durban University of Technology, 2006 xv, iii, 108 leaves / Fibre Reinforced Plastics (FRPs) have been used in many practical structural applications due to their excellent strength and weight characteristics as well as the ability for their properties to be tailored to the requirements of a given application. Thus, designing with FRPs can be extremely challenging, particularly when the number of design variables contained in the design space is large. For example, to determine the ply orientations and the material properties optimally is typically difficult without a considered approach. Optimization of composite structures with respect to the ply angles is necessary to realize the full potential of fibre-reinforced materials. Evaluating the fitness of each candidate in the design space, and selecting the most efficient can be very time consuming and costly. Structures composed of composite materials often contain components which may be modelled as rectangular plates or cylindrical shells, for example. Modelling of components such as plates can be useful as it is a means of simplifying elements of structures, and this can save time and thus cost. Variations in manufacturing processes and user environment may affect the quality and performance of a product. It is usually beneficial to account for such variances or tolerances in the design process, and in fact, sometimes it may be crucial, particularly when the effect is of consequence. The work conducted within this project focused on methodologies for optimally designing fibre-reinforced laminated composite structures with the effects of manufacturing tolerances included. For this study it is assumed that the probability of any tolerance value occurring within the tolerance band, compared with any other, is equal, and thus the techniques are aimed at designing for the worst-case scenario. This thesis thus discusses four new procedures for the optimization of composite structures with the effects of manufacturing uncertainties included.

Deterioration of concrete bridge decks has become a serious problem in the past few decades. Fortunately, non-corrosive, light-weight Fiber Reinforced Polymer (FRP) material provides an excellent alternative. More than 117 bridges in the USA have been built or repaired with FRP. In Canada, no FRP bridge deck has been used in the field, yet. However, Wardrop Engineering Inc., Faroex Ltd., and ISIS Canada have successfully designed, manufactured, and patented the filament-wound Glass Fiber Reinforced Polymer (GFRP) bridge deck. Since there is no design code for FRP bridge decks, a finite element method, labeled “L&D”, is proposed in this thesis to help bridge engineers better understand the structural behavior of FRP bridge decks. The L&D method is validated by comparing the analysis results with the experimental results of three filament-wound GFRP bridge decks. This L&D method is also applicable for analyzing FRP bridge decks manufactured by other processes.

The non-corrodible nature of FRP bars along with their high strength, light weight and ease of installation made it attractive as reinforcement especially for structures exposed to aggressive environment. In addition, the transparency of FRP bars to magnetic and electrical fields makes them an ideal alternative to traditional steel reinforcement in applications sensitive to electromagnetic fields such as magnetic resonance imaging (MRI) units. Continuous concrete beams are commonly-used elements in structures such as parking garages and overpasses, which might be exposed to extreme weather conditions and the application of de-icing salts. In such structures, using the non-corrodible FRP bars is a viable alternative to avoid steel-corrosion problems. However, the linear-elastic behaviour of FRP materials makes the ability of continuous beams to redistribute loads and moments questionable. The objective of this research project is to investigate the flexural behaviour of continuous concrete beams reinforced with FRP and their capability of moment redistribution. An experimental program was conducted at the University of Manitoba to realize the research objectives. Ten full-scale continuous concrete beams were constructed and tested to failure in the laboratory. The specimens had a rectangular cross-section of 200×300 mm and continuous over two spans of 2,800 mm each. The main investigated parameters were the amount and material of longitudinal reinforcement, the amount and material of transverse reinforcement and the spacing of used stirrups. The experimental results showed that moment redistribution in FRP-reinforced continuous concrete beams is possible if the reinforcement configuration is chosen properly, and is improved by increasing the amount of transverse reinforcement. A finite element investigation was conducted using ANSYS-software. A 3-D model was created to simulate the behaviour of continuous beams reinforced with FRP. The model was verified against the experimental results obtained from the present study. This verified model was used to investigate the effect of the concrete compressive strength, longitudinal reinforcement ratio, midspan-to-middle support reinforcement ratio and the amount of transverse reinforcement on the behaviour of FRP-reinforced beams. The analytical results of this parametric investigation along with the experimental results were used to propose an allowable limit for moment redistribution in FRP-reinforced continuous concrete beams.

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No description available.

Fiber reinforced polymer (FRP) composites have been increasingly used inconcrete construction. This research focused on the behavior of concrete columnsreinforced with FRP bars, or prestressed with FRP tendons. The methodology was basedthe ultimate strength approach where stress and strain compatibility conditions andmaterial constitutive laws were applied.Axial strength-moment (P-M) interaction relations of reinforced or prestressedconcrete columns with FRP, a linearly-elastic material, were examined. The analyticalresults identified the possibility of premature compression and/or brittle-tension failureoccurring in FRP reinforced and prestressed concrete columns where sudden andexplosive type failures were expected. These failures were related to the rupture of FRPrebars or tendons in compression and/or in tension prior to concrete reaching its ultimatestrain and strength. The study also concluded that brittle-tension failure was more likelyto occur due to the low ultimate tensile strain of FRP bars or tendons as compared to steel.In addition, the failures were more prevalent when long term effects such as creep andshrinkage of concrete, and creep rupture of FRP were considered. Barring FRP failure,concrete columns reinforced with FRP, in some instances, gained significant momentresistance. As expected the strength interaction of slender steel or FRP reinforcedconcrete columns were dependent more on column length rather than material differencesbetween steel and FRP.Current ACI minimum reinforcement ratio for steel (pmin) reinforced concretecolumns may not be adequate for use in FRP reinforced concrete columns. Design aidswere developed in this study to determine the minimum reinforcement ratio (pf,min)required for rectangular reinforced concrete columns by averting brittle-tension failure toa failure controlled by concrete crushing which in nature was a less catastrophic and moregradual type failure. The proposed method using pf,min enabled the analysis of FRPreinforced concrete columns to be carried out in a manner similar to steel reinforcedconcrete columns since similar provisions in ACI 318 were consistently used indeveloping these aids. The design aids produced accurate estimates of pf,min. Whencreep and shrinkage effects of concrete were considered, conservative pf,min values wereobtained in order to preserve an adequate margin of safety due to their unpredictability.