d. h. mohammed

This paper aims to numerically investigate the structural behavior of reinforced high-strength concrete (HSC) beams retrofitted by Carbon Fiber Reinforced Polymer (CFRP) sheets after cracking. Six pre-cracked HSC beams retrofitted with CFRP sheets having identical reinforcement are numerically tested by four-point loading until failure using Abaqus software, besides two others without CFRP as control beams. CFRP sheets are attached on three beam sides in the shear span after cracking under 60 % of loading. Two shear span distances, two inclinations of CFRP sheets, and the number of sheets are adopted as parameters to compare with the experimental results obtained previously. Test results are matched with the practical findings to calibrate the Abaqus parameters. The results show that retrofitting the cracked beam by CFRP raised its tolerance to the applied load by a range of (13-36) % depending on the shear span to depth ratio and the arrangement of CFRP sheets. When the beam tends to fail in shear, the effect of CFRP is more pronounced than when it tends to fracture in flexure. The inclined sheets are more effective than the vertical ones. Furthermore, two additional parameters are regarded to clarify their effects on the behavior of retrofitted beams: sheet width and concrete compressive strength. Altering the CFRP width does not affect the tolerance, whereas increasing concrete compressive strength raises the beam loading.

This paper demonstrates the effect of adding basalt fibers into a concrete matrix and altering tie spacing on the behavior of short concrete columns since short columns are more robust than long ones and are primarily used in structures. Also, the impact of changing the reinforcement ratio on column behavior is numerically discovered. Three volume fractions of basalt fiber and three-tie spacing are adopted. The results illustrate that no-fiber columns sustain more than 50 % of the failure load before cracking, while this percentage raised to 75 % upon adding basalt fiber to concrete. 0.3 % of basalt fiber increases the compressive strength, cracking and ultimate column loads better than 0.6 %. Likewise, the impact of basalt fiber on the crack load is more pronounced than on the maximum load of the column. Basalt fiber columns exhibit lower longitudinal displacement than no-fiber ones at the cracking state. The shortening increases with increasing tie spacing, whereas decreasing tie spacing barely increases the ultimate load of the column. The numerical analysis provides close results to the experimental ones and shows that increasing the reinforcement ratio raises the column's load capacity. For the same tie spacing, increasing the reinforcement ratio raises the loading capacity of columns, and the longitudinal displacement barely increases upon increasing spacing. Generally, basalt fibers delay cracking and improve the column loading capacity.