Residual strength of reinforced concrete stub columns subject to moderate temperatures

Abstract

This work aims to evaluate the residual strength of reinforced concrete stub columns subjected to moderate temperatures. To accomplish this task, an experimental program was carried out including compression tests on plain concrete specimens exposed to temperatures up to 600 ºC and on reinforced concrete stub columns with two different tie configurations heated at a constant rate for up to 120 min. The results show a loss of residual compressive strength with temperature and the beneficial influence of ties to prevent the spalling phenomenon, although samples with more ties exhibited lower capacity. Finally, the results were compared to the analytical prediction using a cross-sectional approach with idealized stress-strain relations, showing a good correlation. The applicability of the Isotherm 500 ºC method is discussed for moderate temperatures.