Kian Karimi’s research while affiliated with McMaster University and other places

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Publications (7)


Analytical modeling and axial load design of a novel FRP-encased steel–concrete composite column for various slenderness ratios
  • Article

January 2013

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88 Reads

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31 Citations

Engineering Structures

Kian Karimi

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A novel composite column composed of steel, concrete and a fiber reinforced polymer (FRP) tube is presented in this paper. The confinement and composite action between the constituent materials result in enhanced compressive strength, ductility and energy dissipation capacity of the proposed composite column compared to a traditional reinforced concrete (RC) column. Due to the presence of the FRP tube, current design methods for concrete-filled steel tubes (CFSTs) or concrete-encased steel (CES) columns are not directly applicable. An analytical model was developed to predict the behavior of the composite column for various slenderness ratio values. Predicted values are found to be in good agreement with the experimental results from tests of six columns ranging from 500 mm to 3000 mm in height. A parametric study is conducted to investigate the influence of column diameter, FRP tube thickness, axial compressive modulus of the FRP tube and steel-to-concrete area ratio on the capacity relationships and slenderness limits. Finally, a simplified design equation is proposed to predict the compressive load capacity of this type of composite column.


Behavior of Slender Steel-Concrete Composite Columns Wrapped with FRP Jackets

October 2012

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61 Reads

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30 Citations

Journal of Performance of Constructed Facilities

This paper studies the influence of slenderness on the behavior of steel-concrete composite columns encased in fiber-reinforced polymer (FRP) jackets. The composite columns are composed of steel I-sections that are partially encased by concrete and fully wrapped with epoxy-saturated glass and carbon FRP sheets. A total of nine specimens were tested with different slenderness parameters and heights ranging between 500 and 3,000 mm. The confining pressure provided by the FRP jacket and the composite action between the constituent materials resulted in an enhanced compressive behavior of the composite columns. The compressive strength, elastic axial stiffness, and energy dissipation capacity of the composite columns increased by a ratio of up to 5.2, 2.5, and 14.0, respectively, compared with that of the bare steel columns counterparts. A capacity curve, which shows the compressive strength of the composite columns for various slenderness parameters, was developed based on the experimental results. DOI: 10.1061/(ASCE)CF.1943-5509.0000280. (C) 2012 American Society of Civil Engineers.


Influence of Slenderness on the Behavior of a FRP-Encased Steel-Concrete Composite Column

February 2012

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77 Reads

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44 Citations

Journal of Composites for Construction

The compressive behavior of a steel-concrete composite column encased in a fiber reinforced polymer (FRP) tube is evaluated experimentally for columns with various slenderness ratios. The composite column consists of a FRP tube surrounding a steel I-section that is subsequently filled with concrete. A total of nine column specimens were tested ranging between 500 and 3,000 mm in height. Confinement and composite action resulted in enhanced compressive behavior of the composite columns. Maximum confinement occurred in the short column (slenderness ratio less than 0.2). Confinement action reduced with increased height of the column specimens. The column load-carrying capacity, ultimate axial strain, and compressive strength of the confined concrete core in the longest specimen (slenderness ratio of 0.9) were reduced to approximately 59, 14, and 51% of the short column values, respectively. A buckling strength curve of the composite columns was developed on the basis of the experimental results. DOI:10.1061/(ASCE)CC.1943-5614.0000235. (C) 2012 American Society of ivil Engineers.


Testing and modeling of a novel FRP-encased steel–concrete composite column

April 2011

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164 Reads

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121 Citations

Composite Structures

A composite column consisting of steel, concrete and fiber reinforced polymer (FRP) is presented and assessed through experimental testing and analytical modeling. The composite column utilizes a glass FRP (GFRP) composite tube that surrounds a steel I-section, which is subsequently filled with concrete. The GFRP tube acts as a stay-in-place form in addition to providing confinement to the concrete. This study investigates the behavior of the proposed composite columns under axial loading. A total of seven specimens were tested. The influence of concrete shrinkage on the compressive behavior of the composite columns was also investigated. Significant confinement and composite action resulted in enhanced compressive behavior. The addition of a shrinkage reducing agent was found to further improve the compressive behavior of the composite columns. An analytical model was developed to predict the behavior of the composite columns under axial loading.


Performance Enhancement of Steel Columns Using Concrete-Filled Composite Jackets

January 2010

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98 Reads

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30 Citations

Journal of Performance of Constructed Facilities

This paper studies the cross-sectional behavior of steel columns strengthened with fiber-reinforced polymers (FRPs). The composite column is constructed by wrapping the steel I-section column with epoxy-saturated glass- and carbon-FRPs (GFRP and CFRP) sheets in the transverse direction and subsequently filling the voids between the FRP and the steel with concrete. Experimental tests were performed on stub columns under axial compression including one to three CFRP wraps. A corner treatment technique, to avoid stress concentration at the corners and to improve confinement efficiency, was also investigated. A simplified analytical model was developed to predict the axial behavior of the composite columns. Experimental results showed significant enhancement in the behavior of the composite columns primarily attributable to the confinement mechanism imposed by the FRP jacket and concrete. Increasing the corner radius resulted in higher compressive strength of the confined concrete and ultimate axial strain of the composite columns. Good agreement between the analytically developed axial load-displacement relationships and the test data indicates that the model can closely simulate the cross-sectional behavior of the composite columns. DOI: 10.1061/(ASCE)CF.1943-5509.0000162. (C) 2011 American Society of Civil Engineers.


Experimental investigation of two novel FRP retrofit schemes for strengthening steel columns

January 2010

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10 Reads

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2 Citations

Fiber reinforced polymers (FRP) are increasingly being used to retrofit structural members due to their low weight-to-strength ratio and corrosion resistance. Results from an experimental program conducted to evaluate two recently proposed techniques for retrofitting I-shape steel columns are presented. The first retrofit technique involves the construction of a steel-concrete column, which is subsequently wrapped with resin impregnated FRP sheets with the fibers oriented in transverse direction to confine the concrete. The second retrofit technique utilizes a glass FRP (GFRP) composite tube that is placed around the column and filled with concrete. The GFRP tube acts as a stay-in-place form and provides uniform confinement. Slenderness ratios of the retrofitted specimens are selected such that they cover a range of stub to intermediate long columns. Experimental results show significant increase in load carrying capacity and ultimate displacement of the retrofitted columns due to composite action behaviour. The second proposed retrofit technique, using a GFRP tube, provides increased confinement uniformly which results in greater enhancement in the axial behavior of the retrofitted specimens. Confinement efficiency decreased by increasing the specimen length as failure occurred due to overall buckling of the columns.


A novel retrofit technique for strengthening steel columns using FRP

January 2009

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50 Reads

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2 Citations

Fiber reinforced polymers (FRP) are commonly used to repair and/or retrofit concrete and masonry structures. However, compared to concrete and masonry structures the use of FRP for retrofitting steel structures, particularly members such as steel columns and connections, has been limited. This paper investigates a novel retrofit technique to strengthen l-shaped steel columns, through a set of experimental tests on short columns. The proposed retrofit technique involves wrapping the steel column with FRP and filling the voids between the FRP and steel with concrete. In this study, the fiber reinforcement is oriented in the lateral direction to confine the concrete core. Experimental findings including increased load carrying capacity, stiffness and ductility confirm the effectiveness of this proposed technique. A finite element model was developed to analyze the response behaviour of a steel column retrofitted using this proposed technique. Stress distribution contours determined from the finite element analysis of the columns show the unique confinement mechanism.

Citations (6)


... Up to date, FCSRC systems have been adopted to strengthen/repair steel structures [32][33][34][35][36]52,55] and as new hybrid structural members (e.g., hybrid columns, beams [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51]53,54,56,57], or buckling restrained braces (BRBs) [58][59][60][61][62][63][64][65][66][67][68]). Extensive studies have been carried out to understand the performance of such forms of hybrid structural members, and they have been shown to have excellent performance. ...

Reference:

A State-of-the-Art Review of FRP-Confined Steel-Reinforced Concrete (FCSRC) Structural Members
Experimental investigation of two novel FRP retrofit schemes for strengthening steel columns
  • Citing Article
  • January 2010

... Karimi columns and observed that the application of an FRP jacket increased the compressive strength of the concrete by up to 17%. Furthermore, the long composite column specimens demonstrated high stability against global buckling, resulting in an enhanced buckling capacity for long steel columns [6]. ...

Behavior of Slender Steel-Concrete Composite Columns Wrapped with FRP Jackets
  • Citing Article
  • October 2012

Journal of Performance of Constructed Facilities

... As further research has been pursued, the circular CFFT has been extended to square [28], Ishaped steel has been broadened to cross-shaped [3] and channelshaped [29], and the filled concrete has been developed from ordinary concrete to high-strength concrete (HSC) [30] and recycled aggregate concrete (RAC) [31][32][33]. Besides, investigations into the FCSRC have not been limited to the axial and eccentric compressive properties for short columns [34], but mechanical properties of slender column [32,35,36], the flexural performance [37], and seismic performance [33] of FCSRC also have been studied. ...

Influence of Slenderness on the Behavior of a FRP-Encased Steel-Concrete Composite Column
  • Citing Article
  • February 2012

Journal of Composites for Construction

... Also, recent experiments (Cosgun et al. 2019(Cosgun et al. , 2020Khan et al. 2018;Lam et al. 2020;Alavi-Dehkordi et al. 2019) have also indicated that the full performance of the RC beam-column joints is complex due to the variation of stresses in the joint region. In addition, it has been emphasized in the literature that the effect of concrete strength (Murad 2020;Pauletta et al. 2020), the effect of surrounding the columns with beams (Karthik et al. 2020;Khan et al. 2021;Gao and Lin 2021;Massone and Orrego 2018), the effect of stirrup confinement (Adibi et al. 2018;Said and Abdul Razak 2016;Marimuthu and Kothandaraman 2019;Sengupta and Li 2013;Kotsovou and Mouzakis 2012), the effect of column and beam longitudinal reinforcement (Wang et al. 2011;El-Gendy and El-Salakawy 2019;Ibrahim et al. 2018;Tobbi et al. 2014) in others, the column axial load level (Karimi et al. 2012;Mogili et al. 2019;Halahla et al. 2019;Zhao et al. 2019) have important on the column-beam behaviour. In this section of the literature, there are also strengthening studies to prevent seismic damage, as well as studies aimed at defining joint area behaviour (Sharma and Bansal 2019;Antonopoulos and Triantafillou 2003;Faleschin et al. 2019;Majumder and Saha 2021;Ghobarah and Said 2001;Khodaeia et al. 2021;Prota et al. 2004). ...

Analytical modeling and axial load design of a novel FRP-encased steel–concrete composite column for various slenderness ratios
  • Citing Article
  • January 2013

Engineering Structures

... It is measured by deformation ductility (µ) and energy ductility (I 10 ) [34]. Deformation ductility is the ratio of post-peak deformation at 85 % of peak load to deformation at yield, while energy ductility compares the area under the load-strain curve up to 5.5 times the yield strain with the area up to yield strain [34][35][36][37][38][39]. I 10 values around 10 indicate high energy absorption, while values near 1 suggest brittleness [40][41]. ...

Testing and modeling of a novel FRP-encased steel–concrete composite column
  • Citing Article
  • April 2011

Composite Structures

... Fibre-reinforced polymer (FRP) composites have found increasing applications in engineering structures in the past three decades due to their many advantages including their high tensile strength, lightweight nature and excellent corrosion resistance [1][2][3][4][5][6][7][8][9][10]. Among the structural applications of FRP composites, the hybrid uses of FRP with steel and concrete to form novel structural forms, in which the respective advantages of the three materials are exploited, have emerged as a promising direction [4,6,8,[11][12][13][14][15][16][17][18][19][20][21]; the resulting structural members may be collectively referred to as hybrid FRP-steel-concrete (FSC) members. ...

Performance Enhancement of Steel Columns Using Concrete-Filled Composite Jackets
  • Citing Article
  • January 2010

Journal of Performance of Constructed Facilities