... Civil Engineering Structures
Shape memory alloys are identified with several unique phenomena such as the shape memory effect, superelasticity, large damping capacity or a two-way shape memory effect. The iron-based shape memory alloy (Fe-SMA) shows high strength, excellent shape recovery stress, a wide transformation temperature range, high elastic stiffness, low material costs and simple manufacturing process in comparison to NiTi alloys. The Fe-SMA therefore has a huge potential for structural application in particular in the area of reinforcement of new structures or strengthening existing concrete structures. In this talk, recent development and application of shape memory alloys at Empa will be presented.
At Empa, an iron-based shape memory alloy (Fe-17Mn-5Si-10Cr-4Ni-1(V,C) (ma.-%)) has been developed and patented (Dong et al. 2009). Back in 2013, a feasibility study on the usage of the developed Fe-SMA for the strengthening of reinforced concrete structures showed the ability of the developed Fe-SMA for prestressing concrete elements. Several reinforced concrete (RC) beams were strengthened using the near surface mounted (NSM) reinforcement technique with ribbed Fe-SMA strips, as shown in below figures. The recovery stress (prestress force) after prestraining to 2.0% or 4.0% and heating to 160 °C was in the range of 300-350 MPa.
A first on-site application of the Fe-SMA strips took place in May 2017 in Villigen (Switzerland). In this case, the necessity of structural strengthening of a 24-cm-thick reinforced concrete slab in a carpentry was due to the reconversion of the space beneath. Other applications of the iron-based SMA reinforcements including flexural strengthening and shear strengthening have been performed in the laboratory and on site. So far, more than 60 different real application has been realized.
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The fib, Fédération internationale du béton, is a not-for-profit association formed by 42 national member groups and approximately 1000 corporate and individual members. The fib’s mission is to develop at an international level the study of scientific and practical matters capable of advancing the technical, economic, aesthetic and environmental performance of concrete construction.
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The fib was formed in 1998 by the merger of the Euro-International Committee for Concrete (the CEB) and the International Federation for Pre-stressing (the FIP). These predecessor organizations existed independently since 1953 and 1952, respectively.
Негізгі бет Ғылым және технология fib YMG | Development and Application of an Iron-based Shape Memory Alloy in... | Moslem Shahverdi
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