Al-Qadisiyah Journal for Engineering Sciences

Abstract The overwhelming costs of maintenance for reinforced concrete structures due to steel corrosion have motivated researchers to look for alternatives. One of the promising alternatives is Fiber Reinforced Polymer (FRP). Among FRP materials, Carbon FRP (CFRP) is the most attractive material for prestressed concrete members due to its high tensile strength and modulus of elasticity. Previous studies investigated the use of CFRP in prestressed concrete through experimental tests and theoretical analysis. However, there is a significant need for more experimental data to develop an accurate model that can accurately predict the behavior of CFRP prestressed concrete beams. In the current study, experimental flexural tests were conducted on four prestressed concrete beams pre-tensioned with CFRP rods. The length of the beams was 4,270 mm, and the cross-sectional dimensions were 138 x 250 mm. All the beams were subjected to four-point loading with an initial five cycles of loading and unloading before a monotonic loading until failure. Their performance was analyzed, and based on the results a theoretical model was proposed. It was found that the slippage of CFRP at the ends significantly affect the flexural behavior and failure modes of the beams. Additionally, theoretical models must account for CFRP slippage at the ends to accurately predict the flexural response of CFRP prestressed concrete beams. When a slippage reduction factor was used in the proposed theoretical model, the results had a good agreement with the experimental tests. Future research may focus on testing the theoretical model with more data from experimental studies.

Abstract This paper investigates numerically the combined effects of a construction joint and reduction in the cross-section area of negative reinforcement in one-way continuous slab on the structural behavior and the efficiency of three types of strengthens techniques. In this paper, the models were made by ABAQUS (software) are used to numerically represent the specimens and simulate the applied loading. This numerical study's models represent six one-way continuous slabs, as a part of an experimental study. The specimen's dimensions were (2200 mm in length, 500 mm width, and 100 mm thickness). Five of the six models had a vertical construction joint and reduced the negative reinforcement steel bars' cross-sectional area. The sixth specimen is used as reference. The proposed strengthening technique were Carbon fiber Reinforced Polymers strips, 6 mm Carbon fiber Reinforced Polymers bars Near Surface Mountain technique and steel plates. All the proposed strengthening's applied to the tension side on the top face at the internal support. The program outcomes are represented visually as stresses distribution diagrams, load-deflection curves, and cracks pattern. The results from the numerical analysis compared to the experiment results. In the experiment, the reduction in the cross-section area resulting from partial corrosion happened in one span due to the outdoor atmosphere's exposure because of the stoppage in the concrete pouring, which also resulted in forming the construction joint. The results highlighted the construction joint's effect and the steel cross-sectional area reduction on the ultimate load and the deflection. The proposed strengthening methods improved the member's overall responses, and There was a good convergence between the numerical and experimental works that verify the specimens' observed behavior.

Abstract This paper mainly uses ANSYS V.15 , the finite element analysis software, to make nonlinear analysis of reactive powder concrete deep beams . The models simulating the test process were established, the calculation results of ANSYS are compared with the experimental results. Data of eight RPC deep beams tested by researchers were used for comparison with ANSYS models .Furthermore three parametric studies were carried out by changing the size of opening , location of openings and CFRP systems configuration . The comparison shows that ANSYS analysis results are similar to experimental results (the maximum difference in the ultimate load was less than 7.5 %), which indicates ANSYS analysis software can be used to simulate the mechanical property of reactive powder concrete structures.

Abstract The aim of this research is studying the effect of the fibers orientation on the reinforced aluminum specimens. The fibers are made of uniform carboin (0-90) of a volumetric fraction equal to 0.8%. This is for all the reinforcement fiber orientations, using Sikadur -300 resin as connection stuff. Three fiber orientations reinforcements have been used. These orientations are: circular, longitudinal and helical. Then twisting test has been carried out for all the specimens. The test proved that the circular reinforcement improves twisting property, and the helical orientation gives less improvement, while the longitudinal one gives no improvement in the twisting property.