Time-Dependent Behavior of High-Strength Concrete Under High Sustained Compressive Stresses

摘要

Results are reported of an investigation of the behavior of high-strength concrete under sustained stresses in excess of normal working stress levels. The influences of drying and of sustained stresses, ranging from 40 percent up to stress levels above which failure occurs under sustained load, on the shrinking and creep properties of three materials are examined. The long-term shrinkage is shown to be greater for low-strength concrete than for medium- and high-strength concrete. Creep strain, creep coefficient, and specific creep are found to be smaller for high-strength concrete than for normal strength concrete. The influences of high sustained stresses on deformation characteristics are explored and the initiation, propagation, and stability of internal microcracking under short-term and long-term stresses above and below the long-term strengths are investigated. It is concluded that high-strength concrete reveals significantly smaller amounts of cracking at all stress levels than normal strength concrete.