This study presents an assessment of the seismic performance of rectangular concrete columns internally reinforced with G (Glass) FRP. Eight full-scale columns prototypes, with a shear span of 1650-mm and 350-mm square cross-section, were constructed and tested under simulated seismic waves and constant axial loading. These columns simulate the lower portion of first storey columns between the footing and the contra-flexure point. Therefore, heavy steel-RC footing was post-tensioned to the laboratory strong floor in order to provide rational fixity to the column. The test parameters included reinforcement type, longitudinal reinforcement ratio, level of axial load, and stirrup spacing. Test results showed that deformability of GFRP-RC columns prototypes successfully replaced ductility in steel-RC columns in dissipating the seismic energy in the presence of constant axial load. Furthermore, the failure of sections was prominent by flexure concrete crushing at high drifts. Accordingly, GFRP-RC columns are a doable application in earthquake-resistant structures. / October 2015

There has been a growing concern of water scarcity in recent years as global water shortages are increasing. The concrete industry consumes about 2 billion tons of potable water annually. For this reason, seawater has drawn attention as a potential substitute for mixing and curing water for concrete if certain challenges can be addressed. One of the main problems associated with the use of seawater in concrete is the risk of corrosion of internal steel reinforcement. Fibre-reinforced polymer (FRP) bars have been shown to be a viable reinforcement alternative in aggressive environments due to their corrosion-resistant properties. Glass FRP (GFRP) bars, due to their acceptable mechanical properties and reasonable price, are currently the most widely used in industry. GFRP bars are manufactured with a variety of surface configurations having different bond performance in concrete, which influences structural behaviour in concrete flexural elements. Therefore, the viability of GFRP bars with sand coated and spiral deformations in seawater concrete is an important topic for research. In this study the bond behaviour is investigated using two different test methods: 1) pullout specimens, and 2) beam anchorage specimens. The results suggest that there is no significant difference between the short-term bond strength of GFRP bars in seawater concrete compared to normal concrete. Additional research is recommended to explore possible long-term issues.

Precast concrete sandwich wall panels (PCSWPs) have been used in the precast industry for decades due to their durability, rapid construction, and thermal efficiency. Shear connectors are used to connect the two wythes of concrete to allow composite action of the system. The use of glass fiber reinforced polymer (GFRP) connectors is a relatively recent breakthrough in PCSWP design. GFRP connectors allow full composite action to occur, while still maintaining the thermal efficiency of the system by not allowing thermal bridging to occur. In order to design concrete sandwich panel systems to act compositely, the engineer must obtain design values from a connector manufacturer, often times making engineers uncomfortable. Shear connectors are typically proprietary and are required to first have design values often times varies by each company. This project aimed to compare existing testing methodologies in order to better inform engineers about design decisions. This project used two methodologies of shear testing on five different types of composite action connectors. Testing was performed using single-shear and double-shear "push-off" tests. In order to gather enough statistical data to compare the testing methodologies, 22 single-shear and 48 double-shear small scale specimens were designed, fabricated, and loaded through failure at the Utah State University SMASH Lab. Testing was performed by applying loads perpendicular to the connectors and measuring the load and amount of deflection that occurred. Using the load-deflection relationships obtained, stiffness values were calculated and recorded for each test. A statistical analysis was performed based on the observed data. This study concluded that the ultimate strength capacity and stiffness of connectors will change depending on the testing methodology used. Single-shear testing will generally provide less ultimate strength and less stiffness when compared to double-shear testing.

Since concrete bridge deck slabs are much longer in the traffic direction, they experience transverse early-age cracks due to volumetric instability and restraint. In the last decade, the lower cost of the non-corrodible Glass Fiber Reinforced Polymer (GFRP) bars, as alternative to steel reinforcement, has made them attractive to the bridge construction industry. However, low modulus of GFRP bars may lead to wider cracks in GFRP-RC structures. This serviceability issue can be aggravated by harsh environmental conditions. Hence, the main objective of this thesis is to investigate the effect of early-age cracking in restraint bridge deck slabs reinforced with GFRP bars subjected to different environments. This research consists of two phases: an experimental investigation and a numerical study. In the experimental phase, four full-scale cast-in-place slabs reinforced with different longitudinal GFRP reinforcement ratios (0.30, 0.50, 0.70 and 1.1%) and one with steel reinforcement ratio of 0.7% measuring 2500 mm long × 765 mm wide × 180 mm thick were constructed and tested in the laboratory. Three environmental conditions were implemented; normal (laboratory) adiabatic conditions as well as freezing-thawing and wetting-drying cycles. The main test results are presented in terms of cracking pattern, width and spacing, and strains in the reinforcement and concrete. Test results indicated that the minimum reinforcement ratio (0.7%) recommended by CHBDC for bridge deck slabs reinforced with GFRP bars satisfied the serviceability requirements after being subjected to the simulated exposures of normal laboratory conditions, freezing-thawing, and wetting-drying cycles. In the numerical phase of this research, a finite element model (FEM) was constructed using ATENA software package (ver. 5) to simulate the behaviour of the test specimens. According to the FEM results, a reinforcement ratio of 0.45% Carbon FRP (CFRP) can control the early-age crack width and reinforcement strain in CFRP-RC members subjected to restrained shrinkage. Also, the results indicated that changing the bar surface texture (sand-coated and ribbed bars) or concrete cover had an insignificant effect on the early-age crack behavior of FRP-RC bridge deck slabs subjected to shrinkage. However, reducing bar spacing and concrete strength resulted in a decrease in crack width and reinforcement strain. / October 2015

Glass Fibre Reinforced Polymer (GFRP) bars have been developed as an alternative to steel reinforcement for various structural concrete applications. Due to their non-corrossive nature, they are particularly suited for harsh environments where steel reinforcement is prone to corrosion. The purpose of this research is to determine the feasibility of GFRP reinforcing bars as concrete bridge deck reinforcement for locations, such as coastal New Zealand, where the non-corrosive benefits of GFRP may offer an alternative to traditional mild steel reinforcement. GFRP use as structural reinforcement may offer life-cycle cost benefits for certain structures as maintenance to repair corroded reinforcement is not necessary. The use of GFRP reinforcement in a New Zealand design context was investigated to directly compare the structural performance of this alternative reinforcing product. Mateen-bar, manufactured by Pultron Composites Ltd, is the GFRP reinforcing bar used in the experimental tests. Experimental investigation of tensile properties of GFRP bar samples was carried out to understand the mechanical behaviour of GFRP reinforcement and validate the manufacturer’s specifications. This series of tests highlighted the complexities of carrying out tensile testing of FRP products, due to the inability to grip the GFRP directly in a testing machine without crushing the specimen. Two phases of full-scale tests were carried out to compare the performance of bridge deck slabs reinforced with typical mild steel and GFRP reinforcing bar. This experimental testing was different to most existing research on GFRP reinforced slab performance as it did not compare the performance of a GFRP reinforcing bar area equivalent to steel, but was designed in such a way as to dependably give the same moment capacity of the steel reinforced slab design. This incorporated the recommended limit of 20% of design stress given by the manufacturer which led to an apparent over-reinforced section for the GFRP slab design. The aim of the experiments was to investigate the comparative performance of a typical New Zealand bridge deck design and a GFRP reinforced equivalent designed in such a way as is currently recommended by the manufacturer. The over-reinforcement lead to differences in conclusions drawn by other authors who have studied GFRP reinforced slab behaviour. Both flexural and concentrated loading (simulating vehicle loading) tests were carried out on both the steel and GFRP reinforced slab designs. Due to over-reinforcement the GFRP slab was considerably stiffer and stronger than the steel design, indicating that serviceability issues are unlikely to be as much of a design issue as existing literature would suggest. Deflection prediction models generally underestimate the strength of over-reinforced sections. All slabs failed in punching shear under concentrated loads, indicating that punching shear may be a critical failure mechanism for GFRP reinforced slabs Based on the findings from the extensive experimental phases, a set of design recommendations were made to further improve the potential for GFRP to be used for bridge deck design in a New Zealand context.

Glass Fibre Reinforced Polymer (GFRP) internal reinforcing bars are being increasingly considered as a potential corrosion free alternative to regular and stainless steel reinforcing bars. In spite of the availability of code provisions governing both design and certification of the GFRP bars, their use within concrete structures is currently limited to very specific applications unless some behaviour aspects are further investigated. In particular, crack control, ultimate member deformability and the behaviour of the bent GFRP bars are areas in need of such further investigation. An experimental program was conducted consisting of 24 large-scale beams reinforced with various types of GFRP and steel bars complying with CSA certification standards. The results of which show that the stress in the bent bar stirrups at beam failure exceeded minimum code-prescribed values for design (CSA S6, CSA S806, ACI440). An alternative bend-less system of shear reinforcement using straight double headed bars was successful as shear reinforcement but did however result in significant reductions to member deformability. A critical review of the various design provisions incorporating GFRP shear reinforcement, it was found that many of the design codes use conservative shear reinforcement strengths coupled with unconservative values of either the angle of inclination of the compression strut or the concrete contribution to shear resistance. A new relationship for the inclination of the compression strut was proposed for use within the Simplified Modified Compression Field Theory which when combined with the bend/anchor strength of the shear reinforcement correlate well with the experimental results. Also, it was determined that the design strain limits for GFRP shear reinforcement should not be increased until more detailed studies on the long-term performance of the stirrups are conducted. Finally, advanced analysis techniques like layered sectional- and finite element-analysis both gave excellent analytical estimates of the experimental beam response.

Glass Fibre-Reinforced Polymer (GFRP) bars offer a feasible alternative in locations where steel is not the suitable reinforcement; namely locations that are sensitive to corrosion. In this study 60 specimens, 52 GFRP reinforced and 8 steel reinforced, were constructed and tested under direct tension in order to investigate the tension stiffening and cracking behaviour. The effects of different variables such as the bar type, the bar diameter, the reinforcement ratio and the concrete strength on tension stiffening and crack spacing were studied. The current code provisions for tension stiffening, namely ACI-440 and CEB-FIP were evaluated against the obtained test data. It was determined that the current code provisions significantly overestimate tension stiffening in GFRP reinforced specimens. A new tension stiffening model was, therefore, developed that provides better simulation of the test data. The CEB-FIP 1978 model for crack spacing was also modified for GFRP reinforced members.

Glass Fibre-Reinforced Polymer (GFRP) bars offer a feasible alternative in locations where steel is not the suitable reinforcement; namely locations that are sensitive to corrosion. In this study 60 specimens, 52 GFRP reinforced and 8 steel reinforced, were constructed and tested under direct tension in order to investigate the tension stiffening and cracking behaviour. The effects of different variables such as the bar type, the bar diameter, the reinforcement ratio and the concrete strength on tension stiffening and crack spacing were studied. The current code provisions for tension stiffening, namely ACI-440 and CEB-FIP were evaluated against the obtained test data. It was determined that the current code provisions significantly overestimate tension stiffening in GFRP reinforced specimens. A new tension stiffening model was, therefore, developed that provides better simulation of the test data. The CEB-FIP 1978 model for crack spacing was also modified for GFRP reinforced members.

One of the most common building materials is concrete and it has been for a long time. To overcome its low tensile capacity concrete structures are normally reinforced with steel rebars. The use of FRP (Fibers Reinforced Polymers) bars in concrete structures has emerged as an alternative to conventional steel reinforcement, due to the corrosion of steel in aggressive environments. FRP has been used as internal reinforcement for more than 30 years, bridges and parking garages are examples of structures in harsh environments where FRP is a good replacement for steel reinforcement. This due to the higher strength of FRP compared to steel and non-corrosive properties, however FRP as internal reinforcement is not commonly used in Scandinavia. This work has been divided into four parts, a Literature survey, a Literature study on durability, structural behaviour in the serviceability limit state and a FE analysis of previously carried out laboratory tests. In the literature survey the material FPR is described with its components, manufacturing process, history and various applications. A literature study was done to determent the long-term durability of GFRP by accelerated laboratory tests for durability, then compared to field tests on durability of GFRP rebars. The accuracy of FRP design international standards has been evaluated in terms of serviceability limit stat, such as ACI 440.1R-15, ISIS and a variant of Eurocode 2 (EC2). The design models for deflection available for these standards were compared to a database of experimental studies collected by the author. The stiffness of structures reinforced with FRP is such an important parameter so a non-linear calculation using ATENA software was conducted. Results were compared to laboratory tests performed at Denmark Technical University (DTU). In several accelerated laboratory experiments where bare FRP bars were exposed to different harsh environments the degradation of strength was significant, where an alkaline solution at elevated temperature was the harshest environment for the GFRP bars. When GFRP rebars are embedded in concrete the degradation was significantly lower (around 40 percentage points), the concrete protects the GFRP rebars considerably. The largest rate of degradation on GFRP rebars is in the initial state, in comparison to steel which starts to corrode when carbonation and/or chloride penetration critical levels reaches the reinforcement. In field studies there were small signs of degradation of the GFRP rebars, mainly in tropical climates. De-icing salts have a limited effect on the degradation. Laboratory experiments are very conservative with unrealistic harsh environments compared to the natural harsh environments. Therefore, after 20 years of service in harsh environment there were no or small signs of degradation on the GFRP rebars which indicates the validity of GFRP. All three standards evaluated had a large spread on the predicted deflection compared to the experiments, with ACI 440.1R-15 as the most conservative standard with a mean value of the deflection ratio at 0.81. The mean value of the deflection ratio when using ISIS was 0.87, slightly less conservative but with the same spread as ACI 440.1R-15. The calculation using a variant of EC2 had the most spread of results, but with a mean value of the deflection ratio at 0.93, this excluding 11 beams that had an unrealistic prediction due to the wrong prediction of the crack moment. The FEM model created had a similar stiffness as compared to the experiment from DTU, which indicates that the use of Atena was accurate for calculating the deflection of the beams. Although the ultimate load was not well predicted, probably due to the failure mode crushing of concrete in the compressive zone. Despite this, there are many structural parts where FRP could be beneficial, for example in splash zones, in edge beams and slabs etc. This could bring down the costs for maintenance and also prolong the life span of the structure.

In this thesis technical and economic analysis of Fiber Reinforced Composite Polymer (FRPC) bridges was performed. Current condition and main issues of conventional bridges in the world and in Lithuania are assessed, main defects are indicated. In this thesis FRPC is considered as an alternative solution for bridge construction. Application range of FRPC for bridge construction is classified and actual bridge examples are analysed. Further, main properties of FRPC are introduced, taking into account influence of material composition, manufacturing technology, long term effects and advantages over conventional materials. Load-deformation, failure behavior analysis of FRPC bridge decks and bridges revealed advantages over conventional bridge solutions and design issues. In addition, existing codes for FRPC bridge design are analysed, design peculiarities are emphasized and current problems are identified. Performed Life Cycle Cost (LCC) analysis revealed financial viability of FRPC bridges. Finally, main conclusions and problems to be solved are stated and FRPC application potential for bridges construction in Lithuania is suggested. Performed analysis revealed that FRPC application for bridges construction is technically and economically viable solution. / Šiame magistriniame darbe atlikta Pluoštais Armuotų Polimerinių Kompozitinių (PAPK) tiltų techninė ir ekonominė analizė. Nagrinėjama esama pasaulio ir Lietuvos tiltų būklė, nustatytos būdingos problemos bei defektai. Šiame darbe PAPK yra svarstoma kaip alternativi medžiaga tiltų statybai. Atlikta PAPK panaudojimo klasifikacija tiltų statybai, analizuojami esami PAPK tiltų pavyzdžiai bei jų paplitimas. Toliau nustatomos mechaninės bei fizinės PAPK savybės, atsižvelgiant į medžiagos sandarą, gamybos būdą, ilagalaikius veiksnius ir privalumus lyginant su plienu ir gelžbetoniu. Pagal atliktą PAPK tiltų ir perdangų apkrovos-deformacijų, suirimo analizę nustatyta elementų elgsena, pateiktos pagrindinės problemos bei privalumai palyginus su tradiciniais tiltų sprendiniais. Taip pat išnagrinėtos PAPK tiltų projektavimų normos, pateikti skaičiavimų ypatumai bei problemos. Paskutiniame skyriuje atlikta Gyvavimo Ciklo Kainos analizė parodė PAPK tiltų finansinį įgyvendinamumą. Darbo pabaigoje pateikiamos pagrindinės išvados, rezultatai, spręstinos problemos bei PAPK tiltų panaudojimo rekomendacijos Lietuvoje. Atlikta techninė ir ekonominė analizė parodė, jog PAPK panaudojimas tiltų statybai yra techniškai ir ekonomiškai efektyvus sprendimas.