Showing papers by "Zdenek P. Bazant published in 1989"
TL;DR: In this article, a general constitutive law for creep is presented, in which the aging due to continuing hydration of cement is taken into account in a simple manner, and better justified than in existing theories.
Abstract: A new general constitutive law for creep is presented, in which the aging due to continuing hydration of cement is taken into account in a simple manner, and better justified than in existing theories. Microchemical analysis of the solidification process is used to show that the aging may be modeled as a growth of the volume fraction of load-bearing solidified matter (hydrated cement), which may be described as a nonaging viscoelastic material. It was found that a history integral should be used to express the rate, rather than the total value of the viscoelastic strain component. Other study findings are also discussed.
367 citations
TL;DR: In this article, the authors verified and calibrated the theory that was formulated in the preceding paper by comparison with important test data from the literature pertaining to constant as well as variable stress at no (or negligible) simultaneous drying.
Abstract: The theory that was formulated in the preceding paper is verified and calibrated by comparison with important test data from the literature pertaining to constant as well as variable stress at no (or negligible) simultaneous drying. Excellent agreement is achieved. The formulation describing both elastic and creep deformations contains only four free material parameters, which can be identified from test data by linear regression, thus simplifying the task of data fitting. For numerical structural analysis, the creep law is approximated in a rate-type form, which corresponds to describing the solidified matter by a Kelvin chain with nonaging elastic moduli and viscosities. This age-independence on the microlevel makes it possible to develop for the present model a simple version of the exponential algorithm.
224 citations
01 Jan 1989
11 citations
01 Dec 1989
5 citations
Abstract: This paper proposes and evaluates a simple formula for the compliance function for basic creep of concrete. It consists of a hyperbolic sine combined with the double power law. For short creep durations it asymptotically approaches the double power law, and for very long durations it asymptotically approaches the logarithmic law, which is the same behavior as for the previously formulated log-double power law. Compared to the double power law, a significant improvement is obtained in the final slope of the creep curves.
4 citations