Magneto-Electric Active Control of Scaled-Down Reinforced Concrete Columns

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Title: Magneto-Electric Active Control of Scaled-Down Reinforced Concrete Columns

Author(s): Omid Rezaifar, Iman Abavisani, and Ali Kheyroddin

Publication: Structural Journal

Volume: 114

Issue: 05

Appears on pages(s): 1351-1362

Keywords: alternating current (AC) electricity; alternating magnetic field (AMF); compressive strength; current intensity; real-time behavior controlling

Date: 9/1/2017

Abstract:
An exploratory investigation was conducted into the feasibility of improving compressive behavior of reinforced concrete (RC) columns and controlling their structural behavior in real time through interaction between alternating magnetic field (AMF) and alternating current (AC) electricity as actuating systems. For this purpose, some compression experiments were performed on scaled-down RC columns, where AMF of power 0.5 tesla (T) and with frequency of 50 Hz was externally applied to RC columns and/or AC of current intensities up to 36 ampere (A) was run through the reinforcing web. Hence, a specialized test setup comprising magnetic and electric circuits was devised, capable of applying AMF, AC, and uniaxial compression to the specimen simultaneously. For better understanding and discussion about the effect of AMF, some cube specimens of plain concrete (PC) were also prepared, magnetized, and tested. Then the test data for these specimens and those of RC columns were correlated. It was observed that exposing fresh RC column to AMF upon placement facilitates compaction of concrete through vibrating the reinforcing bars, besides a marginal effect on its compressive behavior in the solid phase. But applying AMF to a hardened RC column enhanced the compressive strength by more than 11%, while causing more brittle behavior. On the other hand, employing AC proved to reduce the RC column’s load-bearing capacity but improving ductility. Moreover, the load-bearing capacity and the strength degradation rate in the descending branch of the stress-strain curve of RC columns were experimentally derived as functions of current intensity. Finally, it was found this technique can be a base for real-time compressive behavior controlling of RC members and managing their failure mods through interaction between AMF and AC.