Thermal fields of cracked concrete members in fire

• Temperature distributions in the crack-related region are experimentally examined.
• Air within the extremely narrow crack acts as a thermal insulator to some extent.
• Influences of the width, projected length and inclination angle of the crack are analyzed.
• A simplified method is proposed to predict the thermal fields of the cracked specimens.

Ten concrete specimens (nine with pre-made cracks and one without crack) have been tested in fire to investigate the effect of cracks on temperature distributions of concrete members subjected to post-earthquake fire. After that, a simplified numerical method based on ABAQUS is proposed to determine the thermal fields of the cracked specimens. Three parameters considered in this study include the width, projected length, and inclination angle of the crack. From experimental and numerical investigations, it is found that (a) the measured temperatures on the surface of the pre-made crack for the cracked specimens are generally lower than those on the central cross section of the non-cracked control specimen; (b) when the crack is less than 3 mm wide, the influence of the crack width on the temperature distributions is negligible, and slightly higher temperatures are generally obtained with an increasing of the crack׳s projected length; (c) temperatures on the surface of the pre-made crack for the specimens with inclined cracks are marginally higher than those for the specimens with perpendicular cracks on the whole; and (d) the simplified numerical method is proven to determine the thermal fields of the cracked specimens rationally.