K.Nagai, Y.Sato and T.Ueda Journal of Advanced Concrete Technology, 2(3) 359-374, 2004 Concrete is a heterogeneous material consisting of mortar and aggregate at the meso level. Evaluation of the fracture process at this level is useful to clarify the material characteristic of concrete. However, the analytical approach at this level has not yet been sufficiently investigated. In this study, two-dimensional analyses of mortar and concrete are car-ried out using the Rigid Body Spring Model (RBSM). For the simulation of concrete, constitutive model at the meso scale are developed. Analysis simulates well the failure behavior and the compressive and tensile strength relationship of mortar and concrete under uniaxial and biaxial stress conditions. Localized compressive failure of concrete is also simulated qualitatively.

The authors conduct a fracture analysis on the mortar and concrete by Rigid Body Spring Model (RBSM) that is suitable in failure analysis of brittle material such as concrete, and successfully establish the constitutive equation in the meso-scopic to simulate the aggregate and the sand as constitution material of concrete. Even if the proposed model has many problems in its application to reinforced concrete members, it should be recognized that the paper significantly contributes to the development of numerical analysis technique of concrete material through a newly introduced theory. (Prof. J. Sim, Hanyang University) This paper presents an application of the two-dimensional Rigid Body Spring Model with meso-scale elements. The work provides elegant simulations of the failure behaviour of mortar and concrete specimens under different conditions of loading. (Prof. Christopher Page, University of Leeds)