ANALYSIS OF CONCRETE FLEXURAL MEMBERS REINFORCED WITH FIBRE POLYMER

Analytical model is used in this paper to predict the load carrying capacity of structural concrete members under flexural and normal force which can be concentric or eccentric. The analysis is based on requirement of equilibrium and compatibility of strain in concrete and steel or FRP. The adopted model is based on the real stress strain diagrams for materials. In accordance with this model, the member cross section is covered by a mesh with the smallest cells. After that, stress or strain is determined in each cell and the integral is substituted by the process of summation to define the elements of stiffness matrix. The force vectors equations have nonlinear behaviour. However, in this model, these nonlinear equations are changed to linear equations using the iteration methods with fixity of secant modulus of elasticity in each iteration cycle. In this paper. FORTRAN computer program language is used to compute the force and strains vectors. The comparison between the analytical resaks obtained from the used model and experimental data for other researchers is performed. The analytical model is giving a reasonable agreement between the theoretical and experimental results

SHORT TERM DEFLECTION OF ORDINARY, PARTIALLY PRESTRESSED AND GFRP BARS REINFORCED CONCRETE BEAMS

The behavior of structural concrete beams is studied under short-term loading. A computer program developed originally by Oukaili to evaluate curvature is modified to evaluate the deflection for flexural structural concrete members. The program deals with actual stress-strain relationships of concrete and steel. The analysis is based on requirements of equilibrium and compatibility of strain in concrete and reinforcement. The proposed model is used in conjunction with the step by step analysis for small loading increments that allows the determination of the history of strain and stress in concrete with prestressing steel or non-prestressing reinforcement only or prestressing and non-prestressing reinforcement together. The evaluation of curvatures for the structural member involves iterations for computing the strains vectors at each analysis step. Newmark's numerical integration is used to evaluate the deflection of the member depending on the curvature values. The stress-strain model that was proposed by (Korpenko et al. 1986) is used and compared with experimental data and other analytical models for each of concrete and steel. The comparison showed good agreement between the model used and the experimental data. This relationship is used in SECTION program and presented in this study. The analytical results for load-deflection diagram are compared with available experimental data. The comparison has shown good agreement

Strengthening and Closing Cracks for Existing Reinforced Concrete Girders Using Externally Post-Tensioned Tendons

This research is devoted to study the strengthening technique for the existing reinforced concrete beams using external post-tensioning. An analytical methodology is proposed to predict the value of the effective prestress force for the external tendons required to close cracks in existing beams. The external prestressing force required to close cracks in existing members is only a part from the total strengthening force. A computer program created by Oukaili (1997) and developed by Alhawwassi (2008) to evaluate curvature and deflection for reinforced concrete beams or internally prestressed concrete beams is modified to evaluate the deflection and the stress of the external tendons for the externally strengthened beams using Matlab 7.0. The analytical investigation is implemented on three ideal reinforced concrete beam models, each model is considered to be strengthened using three types of external tendon profile (straight, draped and double draped), where each type of tendon profile is analyzed separately. No comparisons were made with analytical or experimental investigations, because no publications for this kind of studies were found

Flexural behavior and sustainable analysis of polymer bubbuled reinforced concrete slabs

This work presents the flexural capacities and sustainable analysis of reinforced concrete (RC) two way hollow slabs with polymer sphere voids, also known as polymer bubbled RC slab system. A polymer bubbled RC slab has two-dimensional arrangement of voids included to reduce the self-weight. The strength and behavior of bubbled RC slabs with polymer spheres voids is investigated experimentally. Eleven RC square slabs of 1000mm x 1000mm dimensions have been tested to obtain the flexural behavior. Variables of the experimental work are: diameter of polymer spheres, thickness of reinforced concrete slabs, and percentage of Metakaolin (cement replacement). It has been found that bubbled RC slab, (with ratio of bubble diameter B to slab thickness H, B/H=0.51 to 0.80), has about (90 to 100%) of the ultimate load capacity of a similar reference solid slab (which has the same slab thickness). Also, bubbled slabs consume about (70 to 75%) of the concrete needed for the similar solid slab. An increase in the deflection at 0.7