The behavior of thermally-shocked RC columns confined internally by ASWM

In the paper, an experimental program of twenty-four square columns of 200 mm side length and 1000 mm height were tested under the effect of utilizing the ASWM different number of layers (one, two, three. four, and five) as a substitute for stirrup reinforcement within the middle region of the column height, and the effect of thermal shock (damaged or undamaged). The tested columns were divided into two main sets (damaged or undamaged), each consisting of twelve specimens. Sufficient ties were provided at the column ends to prevent premature failure. Moreover, the ASWM provided the columns with the required lateral confinement based on the number of applied layers and the concrete compressive strength. It has been proved that thermal shock reduces the concrete compressive strength, thus degrading the column's performance in terms of its feasibility, strength, and stiffness. The used ASWM layer numbers significantly affect the ductility, energy absorption, and column axial capacity, but this improvement is limited to ASWM numbers of 4 or 5 while stiffness keeps increasing for all values. Furthermore, the average enhancement in the column's axial capacity is equal to 15% on average for the intact specimen. Moreover, this is reduced by approximately 10% under the thermal shock effect.