No abstract

No abstract

A study of the behavior of fibers in high-strength reinforced concrete beams is presented in this paper. Twelve reinforced concrete beams were tested under a pure torsion load. Different compressive strengths (45.2, 64.7, and 84.8 MPa) and fiber volume fractions (0, 0.25, 0.5, and 0.75) with variable spacing between transverse reinforcements have been used. It was discovered that the maximum torque of a high-strength concrete beam is increased by about 20.3, 25.6, and 27.1% when the fractional volume of fiber is increased from 0 to 0.25, 0.5 and 0.75 respectively (when the compressive strength is 45.2 MPa and the transverse reinforcement spacing is 100 mm). The test results show that the ultimate torsional strength becomes higher when the concrete compressive strength increases, and this percentage increase becomes higher with increasing steel fiber volume fraction. When the spacing between transverse reinforcements decreases from 150 to 100 mm, the ultimate torque increases by 19.9%. When the spacing between transverse reinforcements decreases from 100 to 60 mm, the ultimate torque increases by 17.0%. In these beams, the fibers’ compressive strength and volume fraction were kept constant at 45.2 MPa and 0.75, respectively. Doi: 10.28991/CEJ-2022-08-01-07 Full Text: PDF

Combining fiber with concrete mixes has become essential and its widespread use improves the strength of structural concrete elements. This research conducted an experiment into the structural performance of flat slabs with and without a square opening using four types of fiber (hooked-end, straight, corrugated steel fiber and polyolefin fiber) to gain a better understanding of how the variance of fiber type and shape effects the flexural behaviors of two-way slabs. The test program involved (a) testing the properties of hardened concrete, such as compressive properties, modulus of rupture and splitting tensile strength, and (b) testing the flexural behavior of two-way slabs. Ten slabs were divided into five pairs, including two specimens used as reference specimens (with and without openings), and eight other specimens with different types of fibers. Results revealed that the existing fiber in concrete improved the mechanical properties of hardened concrete mix, and the compressive strength test showed higher improvement in specimens with hooked and straight steel fiber. The flexural behavior of reinforced concrete slab was significantly enhanced, and the flexural strength capacity was especially improved for the slabs strengthened with hooked-end and corrugated steel fiber. Polyolefin fiber showed a slight enhancement of mechanical properties and good improvement in flexural capacity. Generally, the highest increments in compressive strength and modulus of rupture were 24.8%, 20% and 11%, and the ultimate load-carrying capacity of slabs was 39%, 13% and 19% for specimens with steel hooked, steel corrugated and polyolefin fibers, respectively, compared with control specimens.