Research Interests

Working first as a structural engineer, I became skeptical of the codified empirical design procedures guarding against quasi-brittle structural failure preceded by distributed cracking and stable fracture growth. The inherent size effects on structural strength were generally attributed to material randomness. My assistants and I demonstrated that this disagreed with experiments. I realized that these effects are caused by stress redistributions and stored energy release, and can be easily captured by asymptotic matching. This led me to a simple size-effect law of surprisingly broad applicability, bridging the power scaling laws of classical fracture mechanics and plasticity. We experimentally verified this law for concrete, rocks, sea ice, fiber composites, toughened ceramics, foams, and snow slabs, and showed its use for identifying cohesive fracture characteristics from experiments. Computer simulation of size effects with nonlocal damage and crack-band models avoiding spurious damage localization and mesh sensitivity followed, so have ramifications to compression fracture, kink bands in fiber composites, extreme value statistics of quasi-brittle failure initiation, microplane models, and micromechanical theory of nonlocality. Currently I am exploring asymptotic techniques for nanoscale, and I continue my long-time researches in creep and hygrothermal effects in concrete, inelastic stability, finite strain, constitutive laws, and probabilistic mechanics.

Membership Type


Election Year


Primary Section

Section 31: Engineering Sciences

Secondary Section

Section 33: Applied Physical Sciences