The present study investigates the torsional behaviour of fire-damaged reinforced concrete (RC) solid square beams with and without stainless steel wire mesh (SSWM) strengthening. Six beams with a cross-section of 150 mm × 150 mm and a length of 1300 mm are cast and tested. Two beams are control samples unaffected by fire and unstrengthened, while four beams are exposed to fire at 400°C. Among the four fire-affected beams, two are strengthened with SSWM and the remaining two are left as unstrengthened. The test results include torque-twist behaviour, failure patterns, ductility index, initial stiffness, and energy absorption capacity. The test results indicated that fire exposure significantly reduced the strength and initial stiffness of the RC solid square beams. However, the application of SSWM for strengthening restored and even enhanced the strength and initial stiffness of RC beams. This suggests that SSWM strengthening is an effective method for improving the performance of fire-damaged RC beams, thus valuable for maintaining structural safety and functionality in post-fire.
Beam-column junction plays an important role in moment-resisting framed structures when subjected to lateral load. Lateral load developed the asymmetric loading effect on an exterior beam-column junction. As a result, among all the junctions, exterior junctions are considered the most crucial under lateral load. The present study is focused on the torsional behaviour of exterior beam-column junction strengthened with stainless steel wire mesh (SSWM). Four 1/3 scale specimens are prepared with a cross-section of 120mm × 150mm for the beam and 120mm × 120mm for the column to study the behaviour of the exterior beam-column junction. Two specimens are considered as control specimens without wrapping, and two are fully wrapped above the beam and near the beam-column junction area using SSWM to avoid shear and torsional failure. The structural response has been measured in terms of displacement and rotation, strain at a junction and load-carrying capacity with the use of LVDT, strain gauge and load cell, respectively. Test results show a significant reduction in the load-carrying capacity and ductility index of unstrengthened specimens compared to SSWM wrapping specimens under torque developed by eccentric loading. Even failure mechanisms, specifically plastic hinge formation, are also affected due to the strengthening of the specimen. The finite element model is developed to understand the behaviour of test specimens and compare the results with experimental studies. The failure pattern, load-displacement and torque-twist response from numerical studies well simulate the response of test specimens observed during the experimental study.
