Torsional Modeling of Reinforced Concrete Beam–Column Joint Retrofitted by Aramid Fiber.

What is it about?

The performance of structural composites during loading has always been a concern for the designers and construction industry since the reinforced concrete structure was discovered. In this study, lateral load–displacement behavior of beam–column joints wrapped with aramid fiber is evaluated using both experimental and numerical analysis subjected to torsional moment (beam-eccentric loading). Three categories of reinforcement concepts are adopted for the preparation of the beam–column joints, where members are wrapped with aramid fiber at the joints, and others are not fortified with aramid fibers. Prior to testing, the structural composites are cured for maximum 28 days into water. The beam–column joints are subjected to lateral load at a point near the column end of the beam–column connection, and the corresponding deflections are measured until the member fails. Based on the test results, ductility and energy absorption capacity are evaluated. The findings of the numerical investigation of beam–column joint show there is not much variation in the experimental and numerical analysis; it is clearly found that aramid fiber wrapping provided large rigidity in the joint, and it is also prolonged the final failure of the joints. This study shows that in addition to the conventional reinforcement, providing the hanger reinforcement and the diagonal reinforcement improves the rigidity of the beam–column joints during severe loadings, as this study described.

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Why is it important?

Reinforced concrete (RC) structure was indisputably the most adopted construction technology around the world because of the crisis of energy that generated by fossil fuels in 1973. Contractors were forced into leaving to build the steel structure as the cost of conventional steel structures increased too much. Moreover, the population growth and a new construction system, like RC composite structure, was invented at the beginning of the 20th century. However, it had limitations affecting its performance negatively when it was exposed to certain loading, i.e., torsional force. For regular performance development, the concrete composite structure was subjected in harsh assessment condition of in terms of stability, rigidity, deformability, and durability. Plastic rotation, an inelastic twisting of beam and column outside the flexible range, is one of the common deformation types at beam–column joints when it is subjected in lateral loading. In an RC composite structure, the overall performance of the structural framework is majorly dependent on the stability, nondeformability, and rigidity on the beam–column joint. The seismic loading, like earthquake, can negatively influence the performance level of the beam–column joint causing the failure for the entire building skeleton. In real-world scenarios, beams of RC beam–column joints are often subjected to loads that are not perfectly centered. For example, if a building has an irregular layout or if the floor loads are not distributed uniformly, the beams may experience eccentric loads. The application of eccentric loads in these situations can help in simulating real-world conditions, allowing for a more accurate analysis of the behavior of the joint [1]. Concrete reinforced with 1.5% bamboo and 2% jute fibers had a maximum flexural strength of 6.36 MPa at 28 days of curing [2]. Concrete containing 10% of Posidonia oceanic fibers had a maximum compressive strength of 33.60 MPa, and their thermal conductivity and thermal diffusivity decreased significantly with the addition of fibers.

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