This thesis investigates the application of ultra-high modulus carbon fiber reinforced polymer (CFRP) plates to strengthen damaged reinforced concrete beams and slender columns. In the first phase, two different pre-repair loading histories were simulated in seven 3000x300x150 mm reinforced concrete beams, namely cracking within the elastic range, and overloading in the plastic range. After unloading, the beams were repaired with either high- or ultra-high modulus (210 or 400 GPa) CFRP plates, or a hybrid system, and then reloaded to failure. It was shown that the level of pre-existing damage has an insignificant effect on the strengthening effectiveness and the failure mode at ultimate. The 210 and 400 GPa CFRP of reinforcement ratio ρf = 0.17% increased the ultimate strength by up to 29 and 51%, respectively, despite the 40% lower tensile strength of the 400 GPa CFRP, due to the change in failure mode from debonding to rupture. Doubling ρf of the 400 GPa CFRP to 0.34% resulted in a 63% overall gain in flexural strength, only 8% increase in ultimate strength over ρf = 0.17%, due to change in failure mode from rupture to concrete cover delamination. The beam retrofitted by hybrid CFRP showed remarkable pseudo ductility and warning signs before failure. However, a parametric study revealed a critical balance in proportioning the areas of hybrid CFRP to achieve reliable pseudo ductility. In the beam with ρf =0.34%, this was achieved using a maximum of 30% ρf of the 400 GPa CFRP. The second phase of this thesis presents an analytical model developed by modifying the provisions of the ACI 318-08 code and employing the computer software Response 2000, to predict the performance of CFRP strengthened slender reinforced concrete columns. Response 2000 is used to establish the interaction curve while the modified ACI 318-08 code is used to acquire the slender column loading path to failure including the second order effects. The model predicts that the effectiveness of the FRP strengthening system increases as the slenderness ratio and FRP reinforcement ratio increase. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-09-24 12:36:48.352

Master of Science / Department of Civil Engineering / Hayder Rasheed / The technology of FRP strengthening has matured to a great extent. However, there is always room for performance improvements. In this study, external bonding of GFRP and near surface mounting (NSM) of regular steel bars is combined to improve the behavior, delay the failure, and enhance the economy of the strengthening. E-Glass FRP is selected due to its inexpensive cost and non-conductive properties to shield the NSM steel bars from corrosion. On the other hand, the use of NSM bars gives redundancy against vandalism and environmental deterioration of the GFRP. An experimental program is conducted in which four rectangular cross-section beams are designed, built, and tested in four-point bending. The first beam is tested as a control beam failing at about 12.24 kips. The second beam is strengthened using two #5 steel NSM bars and 1 layer of GFRP, both extending to the support. This beam failed at 31.6 kips. The third beam is strengthened with the same system used for the second beam. However, the NSM steel bars were cut short covering 26% of the shear-span only while the GFRP was extended to the support. This beam failed at 30.7 kips due to reaching the full flexural capacity of the section at the NSM bars cut off point and the shear stress concentration at the steel bar cut off point. The fourth beam was strengthened with same system as the third beam but then submerged in a highly concentrated saline solution for six months and then tested. This beam failed at a maximum applied load of 29.8 kips, which shows that the GFRP sheet provided good corrosion resistance from the saline solution.

Masonry walls subjected to out-of-plane loading, such as in a seismic event, require reinforcement to improve the ductility of the system. In current masonry construction practice, reinforcement is placed internally and fully grouted. For new construction this can make the wall unjustifiably heavy by not taking advantage of its light, hollow structure. For existing construction, it is difficult to retrofit using this technique. Additionally, the reinforcement is located close to the neutral axis which reduces its effectiveness. Fiber-Reinforced Polymer (FRP) bars, strips and sheets are becoming increasingly popular in construction applications due to their noncorrosive nature and ease of installation. Also, stainless steel bars are used where the structure is exposed to a corrosive environment but have not found wider application for masonry structures. This study is an experimental investigation of the structural performance of masonry walls reinforced with Near-Surface-Mounted (NSM) FRP and stainless steel reinforcement under out-of-plane bending. Additionally, walls with Externally Bonded (EB) FRP sheets were tested. The study simulates retrofitting applications and also proposes the NSM technique for new wall construction, using pre-grooved blocks, in lieu of the conventional method of internal reinforcing and grouting. To accommodate the NSM reinforcement, the grooves in the masonry blocks were aligned with ducts used to anchor the NSM reinforcement in the concrete footing. Seven wall specimens were tested, including walls reinforced with conventional and stainless steel bars, glass-fibre reinforced polymer (GFRP), and carbon-FRP (CFRP) reinforcement. The study demonstrated the feasibility and effectiveness of the NSM technique for new construction. Walls with NSM reinforcement showed a superior performance to those with EB reinforcement. It was shown that increasing the FRP reinforcement ratio may result in a change of failure mode, and as such, the increase in strength may not be proportional to the increase in reinforcement ratio. NSM steel-reinforced walls showed a superior performance in terms of strength, stiffness and the ductility associated with the formation of a plastic hinge at the base. / Thesis (Master, Civil Engineering) -- Queen's University, 2010-05-31 06:24:20.976

Aging bridges in the United States demand effective, efficient, and economical strengthening techniques to meet future traffic requirements. One such technique is to bond steel or fiber reinforced polymer (FRP) plates to the tension faces of reinforced concrete bridge beams with adhesives to strengthen them in flexure. However, beams that have been flexurally strengthened in this manner often fail prematurely, in particular by plate end peeling. The benefits of flexural strengthening by externally bonded reinforcement can only be fully realized by preventing premature failure modes so as to allow the development of composite action between the beam and the external reinforcement. With this goal in mind, several critical limit states of externally reinforced beams are examined in this thesis. Models developed by Roberts (1989) and by Colotti, Spadea, and Swamy (2004) that predict premature plate end debonding are examined in depth using data from previously conducted experimental programs that employed both steel and FRP external reinforcement. In addition, various parameters of the concrete beam, adhesive, and external reinforcement are analyzed in each model to determine the role of each parameter in failure prediction. A critical appraisal of the performance of the models using existing experimental data leads to the selection of the Roberts (1989) model. This model is used to develop recommended design guidelines for flexurally strengthening reinforced concrete bridge beams with externally bonded FRP plates and for preventing premature plate peeling.

<div> <p>Due to harsh environmental conditions, the deterioration of prestressed concrete bridge girders is a commonly observed phenomenon in Indiana and much of the Midwest. Concordantly, one widely observed damage scenario is deteriorated end regions of prestressed concrete girders. Damaged or failed expansion joints expose prestressed concrete girder end regions to chloride-laden water, resulting in a corrosive environment in which reinforcement section loss and concrete spalling can occur. For bridges experiencing this type of deterioration, action is needed to ensure the structure remains safe and serviceable. As such, an experimental program was developed to investigate the effectiveness of three repair techniques in restoring the structural behavior of prestressed concrete bridge girders with end region deterioration. The three examined repair techniques are (i) an externally bonded fiber reinforced polymer (FRP) system, (ii) a near-surface-mounted (NSM) FRP system, and (iii) a concrete supplemental diaphragm. Additionally, installation procedures for the three end region repair techniques were developed. Results, conclusions, and recommendations from the experimental program are presented to help advise best practices for implementing end region repair techniques in the field. </p> </div> <br>

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This diploma thesis presents available FRP software for calculating load bearing capacity of the structures reinforced with FRP and compares them between each other. Furthermore theory and algorithm of my own software is presented here. Load bearing capacity of structures which are reinforced with non-metallic reinforcement and loaded by combination of normal force and bending moment can be solved by my programme. Effects of high temperatures on the concrete structures can be included in the calculation. In the second part of the thesis is calculated load-bearing capacity and deflection of the real beam reinforced with FRP reinforcement and load-bearing capacity of member with FRP reinforcement with effect of elevated temperature. This has been done using my software. Comparison of results from hand calculation and laboratory load-bearing testing is done at the end. This laboratory testing was accomplished by Institute of Concrete and Mansory Structures at our faculty.