CORROSION EFFECT ON SHEAR STRENGTH OF FIBROUS CONCRETE BEAMS
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2021-04-18
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Abstract
During the last few decades, many studies have been conducted to assess the shear performance of steel fiber RC beams. However, most of the previous works have not taken into account the effect corrosion of main steel on the shear behavior of RC beams incorporated with corroded and non-corroded steel fibers (SF).
In this research, the corrosion effect on the shear behavior of steel fiber RC beam has been studied experimentally and numerically.
The experimental program includes the test of nineteen beam specimens with dimensions of 100 x 150 x 1300 mm to evaluate the shear behavior of steel fiber-reinforced concrete (SFRC) beams exposed to corrosion. The tensile reinforcement of the specimens was subjected to 7% and 20% corrosion rates. Volume fractions of steel fibers of 0.8%, 1.2%, and 1.8% were added to the concrete mixes. Four beams were the referenced RC beam with and without shear reinforcement. Two of these beams which without stirrups exposed to 7% and 20% corrosion process. The other three beams without stirrups contained 0.8%, 1.2%, and 1.8% steel fiber did not exposed to corrosion process. While, six beams have contained the same three volume fraction of non-corroded steel fiber subjected to 7% and 20% corrosion, another six beams were mixed with pre-corroded steel fibers at a corrosion rate of 50% to investigate the hybrid effect of the longitudinal reinforcement and steel fiber corrosion on shear performance. The analysis of results was focused on the shear capacity, crack initiation and propagation due to corrosion, mode of failure and midspan deflection.
It was noticed experimentally that the shear capacity of the non-corroded SFRC beams increased by about 68%, 72%, and 82% for the 0.8%, 1.2%, and 1.8% volume fractions of steel fiber, respectively,
compared to RC beams without fiber. Also, the mode of failure was changed from brittle shear failure to flexure-shear or flexure failure for SFRC beams. The improvement of the shear behavior increased with the increase of volumetric ratio of steel fibers. The corrosion in the tensile reinforcement of the beams reduced the load carrying capacity of RC beams by 6%-8% for the corrosion rates of 7% and 20%, respectively. The corrosion also reduced the load carrying capacity of SFRC beams by 10%-22%. Furthermore, both the corroded steel fibers and corroded bars reduced the loads by 6%-37%.
A computer system program (ABAQUS 6.14) was used to develop a finite element model for the analysis of the RC and SFRC beams with and without corrosion effect. The proposed model was validated by using the results of experimental study of RC and SFRC beams of this study. It was found that there is a good convergence between experimental and numerical results. The maximum difference in ultimate shear capacity between the numerical and experimental results was 5%. The simulated model results showed a clear positive effect of the use of the SFs in the RC beams by reducing the deterioration when subjected to corrosion compared to the reference beam.
Finally, it can be concluded that SF can enhance the shear performance of the beams even in a harsh environment.