Title: Experimental and Numerical Predictions of Critical Cooling Temperature for Crack Propagation in Concrete Structures

Author(s): A. Chantelois, P. Leger, R. Tinawi, and M. Veilleux

Publication: Structural Journal

Volume: 96

Issue: 2

Appears on pages(s): 203-211

Keywords: cracking; finite elements; thermal gradient

DOI: 10.14359/611

Date: 3/1/1999

Abstract:
This paper describes an experimental program to induce thermal fracture in notched unreinforced concrete wall specimens subjected to severe cooling thermal gradients. The variations of the compressive and tensile strengths, the elastic modulus, the fracture energy Gf, and the coefficient of thermal expansion of concrete over a temperature range varying from 20 to -40 C have been determined from tests on standard cylinders and three-point bending tests of notched beams. Correlations between experimentally-determined critical temperature conditions to propagate a crack from an existing notch, and 1) linear-elastic, 2) elasto-brittle, and 3) Gf -type smeared cracked thermomechanical finite element analyses, are presented. It is shown that a good correlation between the experimental and numerical cracking predictions from the thermo-elastic response could be obtained using a thermal stress relaxation factor of the order of 0.35. Nonlinear finite element analyses using Gf -type crack models have indicated that there is a large difference between the tensile softening initiation temperature state and the temperature state for complete cracking. The tensile stress-temperature postpeak response is strongly influenced by the magnitude of the fracture energy selected for the analysis.