Stress relaxation in concrete of massive hydraulic structures: Fid-Bau Portal

Stress relaxation in concrete of massive hydraulic structures

Kogan, E. A.

Conclusions 1. New, more reliable data were obtained on the relaxation of stresses in hydrotechnical concrete of various grades, the use of which in designing massive concrete structures permits approximating the data of theoretical and model investigations to the real working conditions of concrete in the structure. 2. Aging of concrete has a quite substantial effect on the degree of stress relaxation; e.g., it differs by a factor of 2–3 for concrete at an age of 3 and 500 days. The effect of aging of concrete on the stress relaxation coefficient must be taken into account to to an age of at least 180 days. Concrete at an age of 3 days is characterized by limiting values Kr(∞, τ) that are close for all three grades and equal on the average to 0.25. Concrete of a mature age is characterized by limiting values of the relaxation coefficient of 0.54 for grade 200 and 0.64–0.67 for grades 300 and 450. 3. Despite the fact that the data obtained on stress relaxation pertain to three specific compositions of concrete of the Toktogul and Inguri dams, the identity and comparatively little difference of the relaxation curves (e.g., for concrete grades 300 and 450) permit recommending their use in engineering calculations of structures being designed with analogous concrete.