• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.121-124
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• 2004

In this paper, a series of fracture tests are performed for the chemically prestressed steel fiber reinforced concrete (SFRC) manufactured with addition of expansive additives for the study of fracture behavior and characteristics. Cracking loads of the chemically prestressed SFRC are greater than that of normal concrete and those are also increased by increasing of steel fiber volume. Thus, it is necessary to obtain optimum steel fiber volume to induce chemically prestressing effectively to concrete members. The result of three-points bending tests shows that early-cracking resistance of the chemically prestressed SFRC is increased without increase of fracture energy. From the test, the tension softening curves are also obtained by poly-linear approximation method and simulated behaviors by using the determined tension softening curves agree with experimental results. And it is confirmed that cracking and ultimate behaviors of chemically prestressed SFRC can be predicted by using obtained fracture characteristics.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.617-625
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• 2009

This study is devoted to the problems of thermal and autogenous expansion stresses in order to avoid cracking using chemically prestressing method. The chemical prestress can be induced by autogenous expansion characteristics of MgO concrete made in specific burning temperature. The volume change induced cracking has great influence on the long-term durability and serviceability. To evaluate risk of cracking, the computer programs for analysis of thermal and autogenous expansion stresses were developed. In these 3-D finite element procedures, long-term autogenous expansive deformation is modeled and its resultant stress is calculated and then verified by comparison with manual calculation results. In this study, the stress development is related to thermal and autogenous expansive deformation. Using the developed program, residual stresses of MgO concrete were compared and analysed in the example From the numerical results it is found that long-term, and temperature dependent expansive concrete with light-burnt MgO is most effective in controlling the risk of cracking of mass concrete because it has high temperature for long period. The developed analysis program can be efficiently utilized as a useful tool to evaluate the thermal and autogenous expansion stresses in mass concrete structures with lightly burnt MgO.