What is it about?
An innovative shear test method known as the Ohno Shear Beam was adopted to measure for the first time the pure shear strength and strain capacity of engineered cement composites. These composites have very high fracture toughness and tensile strain with multiple cracking properties. This work illustrated for the first time that such unique properties of the material are also applicable under pure shear loading conditions. Shear loading is a most severe test of a material's ability to sustain itself against brittle failure. Engineered Cement Composites are designed for high tensile strain capacity and fracture toughness. Ohno shear beams enabled testing of these composite materials to illustrate their shear behavior which is also characterized by ductile metal like strain-hardening behavior. This is quite desirable in structures under earthquake and other severe loading conditions.
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Why is it important?
Shear stresses generally cause sudden brittle failure in structures. Cement-based materials are generally weak in shear and fail catastrophically. Hence shear failure is avoided in structural design. Engineered Cement Composites with high tensile strain capacity also provide high shear strength and strain as measured by the Ohno shear beam tests.
Perspectives
This was part of my doctoral research at the University of Michigan in the nineties when ECC materials were being introduced in the research domain. Shimizu corporation was the sponsor of this research project and supported this work which later resulted in some important practical structural applications in Japan.
Dr Dhanada Kanta Mishra
Hong Kong University of Science and Technology
Read the Original
This page is a summary of: On the shear behavior of engineered cementitious composites, Advanced Cement Based Materials, March 1994, Elsevier,
DOI: 10.1016/1065-7355(94)90045-0.
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