Abstract
A lot of studies have been conducted to introduce self-prestress to structures using Fe-based shape memory alloys (Fe-SMAs). Technology to introduce self-prestress using Fe-SMAs can resolve the disadvantages of conventional prestressed concrete. However, most of the research to introduce a self-prestress force to a structure using Fe-SMAs has been focused on using Fe-SMAs for the repair and strengthening of aging structures. Therefore, in this paper, a study was conducted to introduce self-prestress into a new structure. To this end, in this paper, an experimental study was conducted to evaluate the flexural behavior of self-prestressed concrete slabs with Fe-SMA rebar. Nine specimens were built with consideration of the amount and activation of Fe-SMA rebars as experimental variables. The Fe-SMA rebars used in the specimens exhibited recovery stress of about 335 MPa under the conditions of a pre-strain of 0.04 and a heating temperature of 160 °C. Activation of the Fe-SMA rebars by electrical resistance heating applied an eccentric compression force to the specimen to induce a camber of 0.208–0.496 mm. It was confirmed through a 4-point bending test that the initial crack loads of the activated specimens were 40~101% larger than that of the non-activated specimens. However, the ultimate loads of the activated specimens showed a difference within 3% from that of the non-activated specimens, confirming that the effect of activation on improving the ultimate strength was negligible. Finally, it was confirmed that repetitive activation of the Fe-SMA rebar could repeatedly apply compressive force to the slab.
Highlights
Prestressed concrete is structural concrete in which internal stress is introduced using tendons in areas where tensile stress resulting from the external load is likely to occur
Conclusions can beInrecovered through reactivation evenwas if the prestresstoforce is reduced due tobehavior various this paper, an experimental study conducted evaluate the flexural reasons, such as drying shrinkage and relaxation, unlike conventional bonded prestressed of self-prestressed concrete slabs with Febased shape memory alloys (Fe-shape memory alloy (SMA)) rebar, and the following conclusions were concrete
Drawn: it is judged that the self-prestressing method through Fe-SMA rebar can solve disadvantages the lowrebar strength problem of unbonded prestressed concrete
Summary
Prestressed concrete is structural concrete in which internal stress is introduced using tendons in areas where tensile stress resulting from the external load is likely to occur. The pre-tension method is a method in which the tendons are tensioned before concrete is poured. The post-tension method entails tensioning and anchoring the tendon after the concrete has been cured [6]. Unlike the pre-tension method, it can be applied in the field because separate support is not required. For this reason, the post-tension method is widely used in large-scale construction works such as long-span bridges [7]. The grouting operation complicates the construction process and increases the construction period
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