Title:
Flexural Response of Reinforced Concrete Beams Strengthened with Near-Surface-Mounted Fe-Based Shape-Memory Alloy Strips
Author(s):
Kinam Hong / Sugyu Lee / Yeongmo Yeon / Kyusan Jung
Publication:
IJCSM
Volume:
12
Issue:
Appears on pages(s):
Keywords:
NSM reinforcing method, prestressed strengthening material, Fe-SMA strip, pre-straining level,
DOI:
Date:
6/30/2018
Abstract:
This paper proposes an advanced near-surface-mounted (NSM) technique with an Fe-based shape-memory alloy
(Fe-SMA) strip which can solve issues of low workability and reduced ductility of reinforced concrete (RC) beams
strengthened with an NSM technique using prestressed fiber-reinforced polymer (FRP) strips in the concrete tension
section. The flexural behavior of the RC beam strengthened by the NSM technique with the Fe-SMA strip was
investigated. A total of seven RC beams were tested by four-point bending tests under displacement control. The type
of reinforcements, the quantity of Fe-SMA strips, and the pre-straining level of the Fe-SMA strips were considered as
experimental variables. Cracking load, yielding load, and ultimate load increased, respectively, with larger quantities of
Fe-SMA strip. In addition, activation of embedded Fe-SMA in the concrete by electrical resistance heating effectively
induces a prestressing force on the concrete beam, resulting in a cambering effect. The introduced prestressing force
to the RC beam by activation of the Fe-SMA increased the crack and yielding loads, and did not decrease the ductility
of the RC beam compared to the RC beam with non-activated Fe-SMA. It can be concluded from the test results that
the strengthening technique using the recovery stress of the Fe-SMA strip as the prestressing force solves the various
problems of the existing prestressing strengthening systems, meaning that Fe-SMA can be used as a substitute for
conventional prestressing strengthening systems.