No description available.

A study of the existing data shows that two areas of GFRP bar research among others are in need of investigation, the first being behaviour of GFRP bars at cold temperatures and the second being the behaviour of large diameter GFRP rods. Based on the results of experimental work performed, cold temperatures were found to have minimal effect on the mechanical properties of the GFRP bars tested. In addition, through beam testing, large 32mm diameter GFRP bars were found to not fail prematurely due to interlaminar shear failure. By evaluating the mechanical and durability properties of GFRP bars and behaviour of GFRP RC, it can be concluded that GFRP appears to be an adequate alternative reinforcement for concrete structures. Because of high strength, low stiffness and elastic behaviour of GFRP bars, issues of significant importance for reinforced concrete are bond development, influence of shear on member behaviour and member deformability.

A study of the existing data shows that two areas of GFRP bar research among others are in need of investigation, the first being behaviour of GFRP bars at cold temperatures and the second being the behaviour of large diameter GFRP rods. Based on the results of experimental work performed, cold temperatures were found to have minimal effect on the mechanical properties of the GFRP bars tested. In addition, through beam testing, large 32mm diameter GFRP bars were found to not fail prematurely due to interlaminar shear failure. By evaluating the mechanical and durability properties of GFRP bars and behaviour of GFRP RC, it can be concluded that GFRP appears to be an adequate alternative reinforcement for concrete structures. Because of high strength, low stiffness and elastic behaviour of GFRP bars, issues of significant importance for reinforced concrete are bond development, influence of shear on member behaviour and member deformability.

Given the current global crisis of deteriorating infrastructure, structural rehabilitation has been the focus of much recent research in the field of civil engineering. Consequently, Fibre Reinforced Polymers (FRP’s) are becoming an increasingly common method for retrofitting deficient structures. However, skepticism regarding the structural performance of FRP’s during fire is preventing their widespread implementation in building applications. Because of the degradation of FRP material properties during heating, most current design codes completely neglect their structural contributions in fire design. The intention of this research thesis is to investigate the thermal and mechanical behaviour of insulated FRP retrofitted reinforced concrete structures at elevated temperatures. Two intermediate-scale reinforced concrete slabs were first strengthened with FRP and protected with spray-on insulation. Thermal results from fire testing of the slabs provided a basis on which to develop insulation schemes for larger specimens. These larger specimens consisted of two full-scale T-Beams and two full-scale columns, which were also strengthened with FRP and insulated. All of these specimens succeeded in obtaining four hour fire ratings upon fire testing. Though the FRP strengthening systems were compromised quickly during heating, the insulation provided sufficient protection to the T-beams and columns for them to resist the applied service loads throughout the duration of fire exposure. Detailed calculations were also conducted using thermal data from the full-scale specimen fire tests in order to predict the change in capacity of these structures with time. This thesis shows that, with careful considerations towards insulation and anchorage design, FRP-strengthened reinforced concrete structures are able to obtain fire ratings in excess of four hours. / Thesis (Master, Civil Engineering) -- Queen's University, 2012-05-29 15:46:00.801

No description available.

No description available.

No description available.

No description available.

No description available.

In conventional finite element analysis of reinforced concrete the steel bars are normally assumed to lie along the concrete element edges and very often the bond gripping the steel to the concrete is assumed to be infinitely stiff. The first assumption makes it difficult to model all steel bars leading to the inclusion of only a few representative bars. Shear reinforcement is usually ignored. Thin concrete cover also creates difficulty by causing long thin finite elements in that region. The second assumption does not reflect the true behaviour of the system. In this research a new method for the modelling of steel in reinforced concrete by finite element analysis has been developed which allows all steel reinforcement to be included in the analysis. The method is based on modelling the steel and concrete separately, the two materials being interconnected by the bond forces between them. Thus, bond stiffness is naturally included in the analysis. Such interconnection of steel and concrete is achieved by an interface bond matrix which is derived from the relative displacements between the steel and the concrete at the steel nodes. A linear bond slip relation is assumed for the bond, and a linear stress strain relation is assumed for the concrete and the steel. The work has extended also to nonlinear bond stress-slip relation. Concrete is represented by 8-noded isoparametric quadrilateral elements, and the steel is represented by two noded bar elements. The bond is represented by springs joining each steel node to all 8-concrete nodes. The solution of the resulting system of equations is achieved in an iterative manner which converges quite rapidly, and which requires less computation than the direct solution needs. Three types of problems are analysed in two dimension to demonstrate the application of this new method. These are beam, cantilever and pullout problems. The first two, being real problems, demonstrate the ability of the method to handle complex steel arrangements, thin concrete covers and anchorage of steel, while the third problem shows the application of load to the steel rather than to the concrete. Concrete and steel deformations and stresses are calculated at their nodes. Bond stresses are given at all steel nodes. In the nonlinear bond analysis, deterioration of bond will be demonstrated in pullout and pushout tests at high loads.