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Structural Engineering and Mechanics Volume 41, Number 4, February25 2012 , pages 495-508 DOI: https://doi.org/10.12989/sem.2012.41.4.495 |
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Multi-axial strength criterion of lightweight aggregate (LWA) concrete under the Unified Twin-shear strength theory |
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Li-cheng Wang
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| Abstract | ||
| The strength theory of concrete is significant to structure design and nonlinear finite element analysis of concrete structures because concrete utilized in engineering is usually subject to the action of multi-axial stress. Experimental results have revealed that lightweight aggregate (LWA) concrete exhibits plastic flow plateau under high compressive stress and most of the lightweight aggregates are crushed at this stage. For the purpose of safety, therefore, in the practical application the strength of LWA concrete at the plastic flow plateau stage should be regarded as the ultimate strength under multi-axial compressive stress state. With consideration of the strength criterion, the ultimate strength surface of LWA concrete under multi-axial stress intersects with the hydrostatic stress axis at two different points, which is completely different from that of the normal weight concrete as that the ultimate strength surface is openended. As a result, the strength criteria aimed at normal weight concrete do not fit LWA concrete. In the present paper, a multi-axial strength criterion for LWA concrete is proposed based on the Unified Twin-Shear Strength (UTSS) theory developed by Prof Yu (Yu et al. 1992), which takes into account the above strength characteristics of LWA under high compressive stress level. In this strength criterion model, the tensile and compressive meridians as well as the ultimate strength envelopes in deviatoric plane under different hydrostatic stress are established just in terms of a few characteristic stress states, i.e., the uniaxial tensile strength ft, the uniaxial compressive strength fc, and the equibiaxial compressive fbc. The developed model was confirmed to agree well with experimental data under different stress ratios of LWA concrete. | ||
| Key Words | ||
| lightweight aggregate (LWA) concrete; Unified Twin-Shear Strength (UTSS) theory; multiaxial strength criterion; ultimate strength envelope; tensile and compressive meridians | ||
| Address | ||
| Li-cheng Wang: State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China | ||