Uniaxial Compressive Behavior of Concrete Columns Confined with Superelastic Shape Memory Alloy Wires.

Chenkai Hong,Gangbing Song,Hui Qian

doi:10.3390/ma13051227

Abstract

Superelastic shape memory alloy (SMA) exhibits the ability to undergo large deformations before reverting back to its undeformed shape following the removal of the load. This unique property underlies its great potential in the seismic design and retrofitting of structure members. In this paper, superelastic SMA wires were utilized to confine concrete cylinders to enhance their axial compressive behavior. The axial carrying and deformation capacities of SMA-confined concrete cylinders are assessed by uniaxial compression testing on a total of eight SMA-confined concrete columns and one unconfined column. The influence of the amount of SMA and the prestrain level of SMA wires, as well as the reinforcing mode, on the axial carrying and deformation capacity of confined concrete columns were considered. The analysis focuses on the axial carrying capacity and deformation performance of concrete columns reinforced with superelastic SMA under different loading conditions. Based on the experimental data and analysis results, it is found that superelastic SMA wires can increase the axial loading capacity and enhance deformation performance of concrete columns. Under the same loading condition, the ultimate bearing capacity of SMA-confined concrete columns increases as the increasing of the amount of SMA wire. The results of this study verify the effectiveness of superelastic SMA in enhancing the loading capacity and deformation behavior of concrete cylinders.

Highlights

IntroductionCivil infrastructures are often operated in environments with adverse factors, such as corrosion [1,2], vibration and fatigue [3,4], impacts [5,6,7,8], seismic excitations [9,10,11], strong wind or hurricane [12], among others, and these adverse factors often result in component and/or structural damages, which should be detected and repaired in time to prevent catastrophic events from happening [13]
The results show that the skeleton curve of the concrete columns reinforced by martensitic shape memory alloy (SMA) is similar to the plastic strain curve of concrete columns reinforced by steel casing In addition, in the process of repeated loading, the hysteretic feature of
The axial compressive strength of SMA constrained concrete cylinders can be obtained by linearly superposing the axial compressive strength of unconstrained concrete cylinder and the increased axial compressive strength of the concrete cylinders enhanced by the lateral restraint effect of the superelastic SMA wires; The axial load on the cylinder is fully borne by the concrete, and the superelastic SMA wire does not bear the axial load; The SMA wires are always in a tensioned state, and in reliable contact with the concrete columns

Summary

Introduction

Civil infrastructures are often operated in environments with adverse factors, such as corrosion [1,2], vibration and fatigue [3,4], impacts [5,6,7,8], seismic excitations [9,10,11], strong wind or hurricane [12], among others, and these adverse factors often result in component and/or structural damages, which should be detected and repaired in time to prevent catastrophic events from happening [13]. Structural health monitoring (SHM) [13,14] and damage detection [14,15,16,17,18] and structural retrofit and repair [19,20] have been developed to address these two issues. Retrofitting and repair concrete columns receives increasing attention.

Methods

Results

Conclusion