Title: High-, Medium-, and Low-Strength Concretes Subject to
Sustained Overloads-Strains, Strengths, and Failure
Author(s): Mohammad M. Smadi, Floyd 0. Slate, and Arthur H. Nilson
Publication: Journal Proceedings
Appears on pages(s): 657-664
Keywords: compressive strength; concretes; cracking (fracturing); creep prop-erties;deformation; failure mechanisms; high-strength concretes; loads (forces);strains; stresses.
The behavior of high-strength concrete subject to high sustained compressive stresses was studied experimentally and compared with that of low- and normal-strength concretes. Various forms of stress-strain time relationships were obtained. The long-term sustained strengths were established for these materials and were found to be preater (as percent off,’ > for high-strength than for low-strength concretes by about .5 to 10 percent. The time-dependent deformations were maximum at the vicinity of the sustained strength and were greater the lower the strength of concrete. A hypothesis on the mechanism of failure under sustained loading is presented which states that a critical stage of cracking is initiated by high sustained loads on attaining a critical strain limit that correlates closely with strain at maximum stress in short-time tests.