The effect of LITS on concrete in indirect tension

摘要

The response of concrete to elevated temperatures is an extremely important consideration in the design and rational assessment of structural concrete that may be subject to thermal loading. In this paper is reported more generally some recent research on the load induced thermal strain (LITS), that causes a significant relaxation and redistribution of thermal stresses of concrete beyond the uniaxial compression regime. More specifically, the deformations induced by virgin heating of concrete beams subjected to sustained bending are considered. All experiments were carried out as 3-point bending with plain concrete beams placed in a furnace up to 600℃ with different heating rates and stress levels. To achieve this goal, it was important to study in detail the general modifications of concrete properties at high temperatures and modify the existing universal test machine. Experimental test facilities, equipment and approach are briefly described. Results of specimen strains data are given for LITS during first-time heating, during cooling and second heating. Tests results include weight loss, residual mechanical properties and data on first versus second heating at 0%, 10% and 20% of load among others.