ASCE has honored Zdenĕk P. Bažant, Ph.D., S.E., F.EMI, Dist.M.ASCE, NAS, NAE, with the 2018 Alfred M. Freudenthal Medal for developing a comprehensive theory of probabilistic mechanics of strength, lifetime, and size effect of quasi-brittle structures.
Bažant validated this theory experimentally and computationally, and applied it to structures made of concrete, fiber composites, rocks, and tough ceramics. He demonstrated a conflict between histograms and size effect data for such materials, as well as showed that the evidence for these materials conflicted with the classical Weibull theory. Using the statistical mechanics concepts borrowed from chemistry, he derived the tail of probability distribution of strength at the nanoscale.
He and his students verified their theory from their own tests of concrete, but mainly by numerous test data for coarse-grained ceramics, concrete, and laminates.
Over the last 35 years, Bažant has also made major contributions to probabilistic modeling of concrete creep, shrinkage, and drying effects. He pioneered the estimation of confidence limits on the structural effects of concrete creep and shrinkage. He also presented pioneering applications of Latin hypercube sampling to creep prediction statistics, creep modeling as a random process with independent increments, Bayesian extrapolation of short-time observations of creep on lab specimens or on segmental bridges, and the use of spectral analysis to estimate the effect of random environment.
Although Bažant’s contributions to probabilistic modeling of creep and shrinkage have been important, his development of probabilistic mechanics of quasi-brittle fracture, particularly his size-dependent grafted Gauss-Weibull distribution, stands out as a major contribution that will remain part of the permanent knowledge-base.
The Alfred M. Freudenthal Medal recognizes distinguished achievement in safety and reliability studies applicable to any branch of civil engineering.