Practical Design Criteria for Saturated Pseudo Strain Hardening Behavior in ECC

T. Kanda and V. C. Li

Journal of Advanced Concrete Technology, 4(1) 59-72, 2006

Engineered Cementitious Composites (ECCs) have recently demonstrated their high performance with pseudo strain hardening (PSH) behavior in civil engineering structures and buildings. These ECCs incorporate low cost fibers like Polyvinyl Alcohol fibers which often involve fiber rupture in composites. Such fiber rupture type ECCs tend to have inferior and unsaturated PSH behavior compared with properly designed pull-out type. The present study focused on presenting practical criteria to achieve designing saturated PSH behavior in fiber rupture type ECCs. These criteria were proposed based on two performance indices, which are measures of energy exchange during steady state flat crack propagation and stress level to initiate micro-cracks. The latter performance index necessitated a new cracking strength prediction theory, which was proposed in the current study. Finally the cracking strength theory was justified using tensile test data, and the criteria were proposed based on the data in terms of these two indices.

Practical design criteria for fiber reinforced cement composite with pseudo strain hardening behavior is proposed in the paper. The research is thorough; i.e., the theoretical analysis is extensive and supported by experimental evidence. The proposed design criteria for developing pseudo strain hardening composite are based on micromechanics. Future extension of this research may be meaningful in engineering. (Prof. S. Otani, Chiba University, Japan)