Title:
Effect of High Temperature on Residual Mechanical Properties of Confined and Unconfined
High-Strength Concrete
Author(s):
Bo Wu, Xiao-ping Su, Hui Li, and Jie Yuan
Publication:
Materials Journal
Volume:
99
Issue:
4
Appears on pages(s):
399-407
Keywords:
confined concrete; high-strength concrete; strain; stress; temperature rise.
DOI:
10.14359/12223
Date:
7/1/2002
Abstract:
With the increasing use of high-strength concrete (fc > 60 MPa) in building construction, the risk of exposing these structures to high temperatures during a fire has increased significantly. To be able to assess the structural safety of such structures after a fire, it is important that the mechanical properties of the material be well assessed with regard to high-temperature effects. In this context, a study was conducted to investigate the residual mechanical properties of confined and unconfined high-strength concrete (fc = 70 MPa) after a single thermal cycle at 100, 200, 300, 400, 500, 600, 700, 800, and 900 °C. An analytical model for the stress-strain relationship for uniaxially loaded high-strength concrete was empirically developed and was shown to be applicable to confined and unconfined concrete after a cycle at a high temperature. The main parameters required to establish the stress-strain relationship are the peak stress, the elastic modulus, and the strain at peak stress. Empirical expressions for these parameters were developed to take into account the temperature and the level of confinement. The knowledge of the residual mechanical properties of concrete is necessary whenever the thermally damaged structure is required to bear a significant share of the loads, even after a severe thermal accident.