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.

A limited number of studies have been conducted in the literature in order to investigate the behaviour of high-strength fibre-reinforced concrete (HSFRC) structural components subjected to blast loads. This study summarizes the results of a research program investigating the potential of using steel fibres to improve the blast performance of high-strength reinforced concrete beams. As part of the experimental investigation twenty beams were tested, including nine beams tested under static four-point bending, and eleven beams tested under dynamic blast loads using a shock-tube. Parameters considered in the study include the effect of concrete strength, steel fibres, fibre content, fibre type, longitudinal reinforcement ratio, and presence of shear reinforcement. All beams in the study have identical dimensions, with a cross-section of 125 x 250 mm and length of 2440 mm. To manufacture the specimens, two beams were cast with normal-strength self-consolidate concrete (SCC), with a specified strength of 50 MPa, while the remaining beams were cast with either plain or fibre-reinforced high-strength concrete having a compressive strength which varied between 95-110 MPa. The steel fibre content in the HSFRC beams varied between 0.5 and 1.0%, by volume of concrete. To investigate the effect of reinforcement ratio (ρ), the beams were reinforced with 2-#4 (American size) bars, 2-15M bars or 2-20M bars (ρ = 1.02%, 1.59%, and 2.41%, respectively). The majority of the plain concrete beams had transverse reinforcement which consisted of 6 mm stirrups arranged at a spacing of 100 mm in the shear spans, while most of the HSFRC beams were built without stirrups. The results indicate that all the parameters in this study (reinforcement ratio, presence of stirrups, concrete strength, steel fibres, fibre content and fibre type) affected the static and blast response of the beams, however, the results demonstrate that steel fibres have a more remarkable effect when compared to the other parameters. The provision of fibres is found to improve the blast performance of the HSC beams by increasing shear capacity, reducing maximum and residual mid-span displacements, reducing blast fragments and increasing damage tolerance.

In this thesis the experimental results of seven full-scale glass fiber-reinforced polymer (GFRP) reinforced concrete (RC) slab-column edge connections are presented. The dimensions of the slabs were 2,800×1,550×200 mm with a square column measuring 300×300×2,200 mm. The test connections were divided into two series. Series I included three connections investigating the effect of flexural reinforcement ratio (0.90, 1.35 and 1.80%) when high strength concrete (HSC) is used, while Series II included four connections investigating the effect of GFRP shear reinforcement type and pattern on normal strength concrete (NSC) connections. Test results showed that increasing the reinforcement ratio increased the punching capacity and the post-cracking stiffness of the HSC connections. Furthermore, the use of headed studs and corrugated bars increased the punching capacity and the deformability of the NSC connections. Test results were compared to the predictions of the Canadian and American design provisions for FRP-RC structures. / February 2017

Feasible span-to-depth ratios for many modern bridge systems have been identified and documented in literature. No such parameters have been adequately identified in terms of proportioning bridge piers. This thesis includes a study of 22 existing reinforced concrete highway bridges and their respective pier systems to determine the state-of-the-art in design. The effect of different geometric and material parameters such as concrete strength, reinforcement ratio and slenderness ratio on the structural behavior of individual piers and multiple pier systems was examined. Approximate methods, which may be used for the purposes of preliminary design are discussed and reviewed. Serviceability and ultimate limit states design aids that can be used to identify appropriate preliminary cross-sectional pier dimensions and reinforcement ratios for individual piers given various slenderness ratios were developed. The structural behavior as well as an approach to the preliminary design of multiple pier bridge systems is presented.

Feasible span-to-depth ratios for many modern bridge systems have been identified and documented in literature. No such parameters have been adequately identified in terms of proportioning bridge piers. This thesis includes a study of 22 existing reinforced concrete highway bridges and their respective pier systems to determine the state-of-the-art in design. The effect of different geometric and material parameters such as concrete strength, reinforcement ratio and slenderness ratio on the structural behavior of individual piers and multiple pier systems was examined. Approximate methods, which may be used for the purposes of preliminary design are discussed and reviewed. Serviceability and ultimate limit states design aids that can be used to identify appropriate preliminary cross-sectional pier dimensions and reinforcement ratios for individual piers given various slenderness ratios were developed. The structural behavior as well as an approach to the preliminary design of multiple pier bridge systems is presented.

Dėl sąveikos su armatūros strypais iš esmės pakinta tempiamojo betono fizikinis įtempių ir deformacijų būvis, todėl taikyti vientiso tempiamojo betono įtempių ir deformacijų diagramas negalima. Armuotojo betono atveju šios diagramos yra pakeičiamos vadinamosiomis tempiamojo sustandėjimo įtempių ir deformacijų diagramomis, tačiau iki šiol nėra priimta bendro metodo, kaip jas reikėtų apskaičiuoti. Baigiamojo magistro darbo tikslas – pasiūlyti tempiamojo betono įtempių ir deformacijų fizikinį modelį. Baigiamajame darbe atlikta kritinė literatūros šaltinių betono tempiamojo sustandėjimo tematika analizė. Atlikti tempiamųjų gelžbetoninių elementų eksperimentiniai ir skaitiniai tyrimai. Literatūros šaltiniuose aptiktų eksperimentinių tyrimų rezultatai palyginti su atliktais eksperimentiniais ir skaitiniais tyrimais. Pagal atrinktus duomenis išvestas tempiamojo betono įtempių ir deformacijų fizikinis modelis bei atlikta jo statistinė analizė. Baigiamąjį magistro darbą sudaro įvadas, trys skyriai, išvados bei literatūros sąrašas. Darbo apimtis – 64 puslapiai. Tekste pateikta 50 formulių, 41 paveikslas ir 10 lentelių. Rašant darbą remtasi 30 literatūros šaltinių. / Interaction between concrete and reinforcement changes the way tensile concrete behaves thus the stress–strain relationship for solid tensile concrete cannot be applied anymore. In the case of reinforced concrete, these graphs are changed with so–called tension stiffening diagrams but until now there has been no confirmed method that would allow us to determine it. The aim of the master thesis is to propose a physical model for stress–strain relationship of tensile concrete. In the master thesis a close analysis of a number of scientific articles about tension stiffening has been done. Experimental and numerical research for tensile reinforced concrete members has been performed. The data found in scientific articles has been compared with the data of experimental and numerical research. Based on the results of experimental research a physical model for stress–strain relationship of tensile concrete has been proposed, also a statistical accuracy analysis of the model has been performed. The master thesis consists of introduction, three chapters, conclusions and references. Total number of pages is 64. Thesis includes 50 equations, 41 figures and 10 tables. Paper refers to 30 scientific source materials.

Experiments were conducted to investigate the punching shear behaviour of thick slabs with identical spans and depths, subjected to monotonic point load conditions. Variables included: reinforcement ratio, column size, and reinforcement size. Analytical studies conducted as part of this thesis indicate that the current CSA A23.3 and the ACI 318 can be unconservative for thick slabs with low reinforcement ratios. The new fib Model Code provisions for punching offer an effective method for determining the full load-rotation behaviour of a slab up to failure, including accurate failure predictions. A summary of the background of current design procedures and standards will be presented, and a comparison between the different design equations and theories will be given. Based on the findings of this project, it is proposed that the provisions accepted by the fib Model Code should be considered for implementation in the CSA and ACI standards.

Experiments were conducted to investigate the punching shear behaviour of thick slabs with identical spans and depths, subjected to monotonic point load conditions. Variables included: reinforcement ratio, column size, and reinforcement size. Analytical studies conducted as part of this thesis indicate that the current CSA A23.3 and the ACI 318 can be unconservative for thick slabs with low reinforcement ratios. The new fib Model Code provisions for punching offer an effective method for determining the full load-rotation behaviour of a slab up to failure, including accurate failure predictions. A summary of the background of current design procedures and standards will be presented, and a comparison between the different design equations and theories will be given. Based on the findings of this project, it is proposed that the provisions accepted by the fib Model Code should be considered for implementation in the CSA and ACI standards.