Journal of Advanced Concrete Technology
Online ISSN : 1347-3913
ISSN-L : 1346-8014
Volume 20, Issue 8
Displaying 1-3 of 3 articles from this issue
Scientific paper
  • Eissa Fathalla, Boyan Mihaylov
    2022 Volume 20 Issue 8 Pages 507-524
    Published: August 12, 2022
    Released on J-STAGE: August 12, 2022

    In this paper, a simplified model is proposed for the shear strength of short shear walls based on the original three-parameter kinematic theory (3PKT). The model is built on first principles – compatibility of deformations, constitutive relationships and equilibrium – and aims to combine simplicity and accuracy for structural assessment applications. The model focuses on shear failures along diagonal cracks, while other failure modes such as sliding shear, out-of-plane instability, or detailing/lap splice failures need to be evaluated separately. The simplified 3PKT is validated with 29 specimens with a wide range of properties and is compared to the ASCE (ASCE 2014) and Japanese (AIJ 2001) seismic code shear provisions. It is shown that the model captures well the effect of all key test variables, and significantly reduces the conservatism and scatter of the code strength predictions. It is also shown that the proposed approach can be particularly helpful in the assessment of structures with less-than-minimum shear reinforcement to avoid costly and disruptive strengthening interventions.

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  • Lei Chang, Hui Liu, Deyu Yue, Yali Wang, Suping Cui, Jianfeng Wang
    2022 Volume 20 Issue 8 Pages 525-534
    Published: August 13, 2022
    Released on J-STAGE: August 13, 2022

    Steel slag as a solid waste during steel-making has potential cementitious activity, and its use as supplementary cementitious material is an effective way to improve its resource utilization. Ethanol-diisopropanolamine (EDIPA), as an organic admixture, affects the hydration of the steel slag-cement composite system. In this paper, the effect of EDIPA on the hydration and mechanical properties of the steel slag-cement composite system was investigated by using mortar strength tests and combining with heat of hydration, X-ray diffraction (XRD), thermogravimetry/differential thermogravimetry (TG/DTG), scanning electron microscope (SEM) and other testing methods. The results show that EDIPA can improve both early and late compressive strength of steel slag-cement mortar at low dosing (0.02%). However, at high dosing (0.06%, 0.10%), EDIPA is unfavorable to early strength, but enhanced late strength more strongly than low dosing. Low dose of EDIPA can promote the hydration of steel slag-cement composite pastes, and can also improve the hydration degree in the early and late stages. At low dosing, EDIPA can promote the formation of ettringite (AFt) and facilitate the transformation from AFt to monosulfoaluminate (AFm). In addition, EDIPA affects the crystal structure and morphology of Ca(OH)2 prepared by co-precipitation method. And the morphology of Ca(OH)2 gradually changes from long hexagonal column to short hexagonal column and then to irregularly radiating lamellar with the increase of EDIPA dosing. This indicates that EDIPA inhibits the vertical growth of Ca(OH)2 and has the reference sig-nificance for the change of Ca(OH)2 morphology in the composite paste.

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  • Edom Zewdie, Masoud Soltani, Koichi Maekawa
    2022 Volume 20 Issue 8 Pages 535-549
    Published: August 24, 2022
    Released on J-STAGE: August 24, 2022

    The extended multi-directional non-orthogonal crack model was applied to the joint interface area between RC members connected by shear dowel and the experimental verification was conducted in use of the low cycle fatigue experiments. The splitting tension field induced by the dowel action around the reinforcing bar is successfully reproduced with the coupled joint crack model and the beam finite elements, and the splitting tension cracking under cyclic fatigue loading and the joint degradation were fairly captured computationally. The effect of spiral steel confinement on the shear dowel performance can be quantitatively evaluated by the generic full 3D nonlinear analysis.

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