Circular and square columns strengthened with FRCM under concentric load

doi:10.1016/j.compstruct.2020.113000

Composite Structures

Volume 255, 1 January 2021, 113000

https://doi.org/10.1016/j.compstruct.2020.113000 Get rights and content

Abstract

Fiber-reinforced cementitious matrix (FRCM) systems have recently emerged as an innovative technique to strengthen and retrofit reinforced concrete structures. These non-corrosive systems involve the use of high strength reinforcing textiles sandwiched between layers of cementitious mortars. This paper aims to study the effect of retrofitting newly constructed short columns with FRCM using PBO type of textiles. The experimental program consisted of testing 4 rectangular columns and 4 circular columns under concentric loading. All columns had a reinforcement ratio of 0.02 and were cast with concrete of 30 MPa compressive strength. For each type of cross-section, columns were wrapped with 1, 2 or 4 layers of PBO FRCM. Overall, the strengthened columns exhibited higher load carrying capacity than their control unwrapped counterpart with an increase ranged between 5.1% and 36%. The confining effect of FRCM layers was more pronounced in the circular columns than in the square ones. It was also noticed that all columns exhibited similar responses in terms of load -strain relationship irrespective of the column shape and the number of FRCM layers used. Furthermore, the displacement levels increased as the number of layers increased which indicated an increase in ductility of columns wrapped with FRCM.

Section snippets

Introduction and background

The process of rehabilitating reinforced concrete (RC) structures can be intricate and costly. This has led the construction industry to constantly look for alternative techniques that are more convenient and less expensive. One of the techniques that has emerged in the last decades is the externally bonded (EB) systems, which wrap the deteriorated structures with composite materials. Fiber-reinforced polymers (FRP) are the most popular materials used in concrete wrapping. However, due to

Experimental program

The test matrix of the experimental program is shown in Table 1. The matrix consisted of eight RC columns divided into two groups according to their cross sections. In each group of columns, one unwrapped control column served as a benchmark while the other three columns were wrapped with one, two, and four layers of PBO-FRCM, respectively. In Table 1, the letter in the column’s label refers to its cross section (S for a square cross-section and C for a circular cross-section). The letter is

Test results and discussion

Table 4 summarizes the experimental results in terms of the peak loads, the corresponding strains in concrete and in the reinforcing bars, and the modes of failure associated with each column.

Conclusions

The behavior of concentrically loaded columns strengthened with different number of PBO-FRCM layers was presented. The following conclusions can be drawn:

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Circular columns strengthened with two and four layers of PBO-FRCM had a higher capacity than the square strengthened columns, where the circular column strengthened with one layer had a lower capacity due to probable errors that occurred during PBO-FRCM installation.
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Control columns failed by concrete crushing, square columns strengthened with

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

The authors would like to acknowledge the financial support provided by the American University of Sharjah (AUS Grant No. FRG19-L-E23).

Data availability statement

The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.

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Circular and square columns strengthened with FRCM under concentric load

Abstract

Section snippets

Introduction and background

Experimental program

Test results and discussion

Conclusions

Declaration of Competing Interest

Acknowledgement

Data availability statement

Compos B Eng

Constr Build Mater

Compos Struct

Compos B Eng

Constr Build Mater

Eng Struct

Eng Struct

Constr Build Mater

Compos B Eng

Constr Build Mater

Constr Build Mater

Compos B Eng

Combined impressed current cathodic protection and FRCM strengthening for corrosion-prone concrete structures

J Compos Constr

Seismic response analysis of masonry minaret and possible strengthening by fiber reinforced cementitious matrix (FRCM) materials

Adv Mater Sci Eng