 Open Access
 Total Downloads : 72
 Authors : Athar Hussain , Harshit Sethi , Rashid Shams , Inder Kumar Yadav
 Paper ID : IJERTV8IS090224
 Volume & Issue : Volume 08, Issue 09 (September 2019)
 Published (First Online): 02102019
 ISSN (Online) : 22780181
 Publisher Name : IJERT
 License: This work is licensed under a Creative Commons Attribution 4.0 International License
Analysis of the Composite Columns using Finite Element Modelling in Ansys Environment
Athar Hussain1,
1. Associate Professor, Civil Engineering Department,
Ch. Brahm Prakash Government Engineering College Jaffarpur, New Delhi73.
Harshit Sethi 2,
2. M. Tech Student, Gautam Buddha University, Greater Noida ,Uttar Pradesh.
Rashid Shams3, Inder Kumar Yadav3
3. Under Graduate Student Civil Engineering Department, Ch. Brahm Prakash Government Engineering College Jaffarpur,
New Delhi73.
Abstract: In the present study, an attempt has been made on analysis of the composite columns using finite element modelling in ANSYS environment. The static structural module approach has been used to work out specific parameters under a uniformly distributed impact load. A total of twentyone column cases were analyzed and investigation of the output values has been carried out and compared. The results indicate that the confinement effect of composite columns provide enhancement of strength and ductility up to a certain column height.
Keywords: Confinement, Retrofitting, Steel columns, Finite element analysis (FEA), Composite columns.

INTRODUCTION
Composite materials, plastics and ceramics have been talk of the town for over the last three decades. They have conquered the market covering massively all the domains and sections with its wide range of applications. The most recent engineered material market is ruled by composite materials since most of the day to day life products and alcove applications require them. Composite materials can be varied by making changes in their structural aspects unlike materials like cement, steel etc. Any component made up of composites needs both material and structural design. The designer has the control of varying the properties of composites such as stiffness, thermal expansions etc. A lot of studies and analysis is involved while composing a result with composites such as careful selection of reinforcement types which help in achieving specific engineering requirements. Polymeric composites are the most common matrix materials. There are two major reasons. It is because mechanical properties arent satisfactory enough for the structural purposes. The stiffness and strength are low as compared to ceramics or
even any metal. This can be overcome by reinforcing polymer with other materials.
Fibers are thread like pieces which are in the form of continuous elongated hair like filaments. Composite materials use them as a component. The main advantages of natural fibre composite include having a low specific weight, resulting in a higher specific strength and stiffness than glass fiber. It is a renewable source of energy which gives out oxygen using carbon dioxide and can be generated with low investment at low cost.
Hemp is a bast fibre such as jute, flax and ramie. It possesses excellent qualities of durability, fibre strength, length, absorbency and antimicrobial properties. Cheap and efficient concrete can also be produced using hemp extracts. FRP is a polymer matrix reinforced with fibres. Fibre is the main source of strength while matrix glues all of them together in shape and stress handling positions. The loads are carried along longitudinal directions. Columns are typically wrapped with FRP around their perimeter, as with closed or complete wrapping. This not only results in higher shear resistance, but more crucial for column design, it results in increased compressive strength under axial loading. FRP jackets and reinforcements are costeffective alternatives to concrete or steelplate jackets. They can be used to considerably increase ductility and strength without increasing stiffness [1][2]. The two specific design considerations prove to be very beneficial for FRP. First, because of its inert nature, FRP can provide protection against corrosion and stray electrical currents. Secondly, FRP wrapping and jackets can be fabricated to meet specific requirements desirable to a specific structure by adjusting the orientation of the fibres in various directions.
Rule of Mixtures
Fig.1. Typical finite element model used in the analysis of concrete column (confined) loaded in compression. [3].

LITERATURE REVIEW
The type, form, quantity and formation of the constituents determine how the mechanical and physical properties of composite materials will be. The rule of mixtures is set of equations which determine these values. It is noted that the unidirectional ply has two different inplane tensile moduli (E1 and E2). [4][5]
Longitudinal modulus, E1 denoted by equation 1 as:
E E V E V E V E 1V
……………………………………………………..(1)
1 f f m m f f m f
Poissons ratio, v12 is denoted by Equation 2 as: ……………………………………………………………………………………………………(2)
Transverse modulus, E2 as shown through Equation 3 as:
1 Vf
E2 Ef
Vm …………………………………………………………………………………………………..(3)
Em
and Shear Modulus, G12 represented through Equation 4 as:
1
G12
V f
G f

Vm
Gm
……………………………………………………………………………………………………(4)
Where, the terms Ef and Em are the Elastic modulus of fiber and matrix respectively and Gf and Gm are the Shear modulus of fiber and matrix respectively. The terms Vm and Vf are the Volume fractions of matrix and fiber respectively, and W and represents weights and densities of the respective materials. In the given unidirectional composite, the voluminous capacity of the composite may be represented as Equation 5 and 6:
=
+
=
+
…………………………………………………………………………………………………….(5)
……………………………………………………………………………………………………..(6)
Different researchers have studied pertaining to analysis of FRP columns. Stephen Pessiki (2001) has performed experiment on the small circular and square plain concrete and large scale circular and square reinforced concrete confined with fiber reinforced polymer (FRP) composite jackets, subject to monotonic, concentric axial loads and found that axial stress and strain capacity has increased in relative to that of unconfined concrete and increases with the increase in FRP jacket. J.J. Zeng (2018) has experimented on the Behavior of largescale FRPconfined rectangular RC columns under axial Compression and found that the compressive strength of concrete in a large
scale unconfined concrete column was found to be lower than that of a standard concrete cylinder and was found to be 6% lesser than the conventional concrete the compressive strength and the ultimate axial strain increase with the increase of corner radius ratio or the FRP jacket thickness. JunJie Zeng (2017) tested for axial compression on 33 column specimens and studied the compressive behaviour of circularized square columns (CSCs) and found that significant strength and deformation increases are obtained for the FRPconfined CSCs compared to the fully FRPconfined square columns without circularization and also increase in the net spacing leads to a decrease in
the ultimate axial stress and increase in the FRP volumetric ratio leads to an increase in both the ultimate xial stress and the ultimate axial strain.
Rami Eid (2017) has experimented in six FRP/TRP confined reinforced concrete columns under compressive axial loading and analyzed the behaviour of circular, square and rectangular columns. the higher the number of FRP layers, the higher the axial concrete compressive strength and its corresponding strain and this is well documented in the literature of Marijn R. et al., (1999), Laura De Lorenzis et al., (2003), Silvia Rocca et al., (2008). Nadeem A. Siddiqui (2014) has experimented on the effectiveness of hoop and longitudinal Carbon FRP (CFRP) wraps in reducing the lateral deflections and improving the strength of slender circular RC columns and was experimented on a total of 12 smallscale circular RC columns of 150 mm diameter. The results showed that CFRP hoop wraps provide confinement to concrete and lateral support to the longitudinal fibers and thus increase the strength of both short and slender RC columns. However, the effect of hoop wraps on the strength of columns is more significant for short columns than slender columns. Marinella Fossetti (2018) In this paper a generalized criterion for the determination of the increase in strength, in ductility, and in dissipated energy for varying corner radius ratios of the cross section and fiber volumetric ratios is shown. Numerical results using a finite element analysis, calibrated on the basis of experimental data available in the literature, are carried out to calibrate the new analytical models and results shows that the strength increase does not require definition of the lateral confinement pressure.
Thomas Vincent (2015) experimented on the influence of shrinkage on compressive behaviour of concrete filled FRP of FRPconfined normal and highstrength concrete (NSC and HSC). A total of 30 aramid FRP (AFRP) confined concrete specimens with circular crosssections were manufactured. Six of the specimens were instrumented to monitor long term shrinkage strain development of the FRPconfined NSC and HSC, with three specimens allocated to each mix. The remaining 24 specimens were tested under axial compression, where nine of these specimens were manufactured with NSC and the remaining 15 with HSC and results shows that there is a decrease in strength enhancement ratio whereas it leads to a significant increase in strain enhancement ratio and also decrease in the ratio of the ultimate axial strains obtained from mid section and fullheight LVDTs (MLVDT/ FLVDT) due to a partial or complete loss of bond at the interface between the concrete core and FRP shell.
Manal K. Zaki (2011) experimented on cylindrical reinforced concrete (RC) columns confined with fiber reinforced polymer (FRP) composites. The columns
studied are under combined axial loads and biaxial bending moments. The fiber method modeling (FMM) together with finite element analysis (FEA) are adopted to investigate the behavior of such columns and results shows that a remarkable increase in the tension zone can be achieved due to the contribution of the longitudinal direction of the FRP in flexural capacity. For columns under uniaxial bending, a remarkable increase in Mu and Fxu are recorded by FRP confining. The increase in column capacity of the FRP confined columns compared to the reference columns increases as the balance point is approached and similar results were from J.L. Pan (2007). Haider Al Abadi (2016) investigated for the individual effect of the confinement parameters including unconfined concrete strength and confining pressure on the strength of FRPconfined concrete cylinders and results show that utilizing a FRP jacketing material which contains a higher tensile strength will not be effective when used to confine high strength concrete samples.


MATERIALS AND METHODS
Certain materials were used to perform the modelling according to their respective codes and specifications. The materials used are Concrete and Structural steel for the composite columns, and Epoxy Resin matrix and a 100% Hemp composite is used to form a fresh composite. (CTPT12) [3]. The fresh composite so formed includes 30% of Hemp fibres and remaining 70% is the epoxy resin which binds the fibres together to provide exceptional tensile strength to the composite. New Composite formed is denoted as FRP. Thus, FRP ingredients can be written as:
FRP ingredients = 70% Epoxy resin + 30% Hemp fibers
The reinforcements as well as the HSection bar is made up of structural steel conforming to Grade A of IS 2062. The dimensions of HSection column are defined as per GB standard Beams (300x300x10x15) mm.
FRP Casing Properties
The FRP jacket provided in the problem is derived from combining two different materials viz. Hemp Fibers (30%) and an Epoxy resin matrix (70%). The composite so formed is employed in designing the FRP jacket and comprises of 10 layers of the new formed composite, 0.8 mm thick each. Further a 0.8 mm layer of Epoxy is provided in between these layers and the column to make the adhesive bond firm and a 0.2 mm spray of Epoxy resin is also taken in consideration at the outer face of the FRP after the layers are applied. The orientations of the composite laminas are unidirectional (0Â°) and are parallel to the axial load direction. The properties of different materials used in the analysis are provided in table 1. [3]
Table 1: Mechanical properties of materials used in the FEM analysis
MATERIAL / PARAMETER
Concrete
Structural Steel
Hemp fiber
Epoxy resin
FRP
Density (g cm3)
2.3
7.85
1.249
1.16
1.1042
Young's Modulus (MPa)
30000
2.e+005
6460.849
3780
4490.4
Poisson's Ratio
0.18
0.3
0.06
0.35
0.27315
Bulk Modulus (MPa)
15625
1.6667e+005
2447.3
4200
3299.1
Shear Modulus (MPa)
12712
76923
3047.6
1400
1763.5
Table 2: Layup of the layered section of composite
Layer
Material
Thickness (mm)
Angle (Â°)
12
Resin Epoxy
0.2
0
11
HEMPEPOXY COMPOSITE
0.8
0
10
HEMPEPOXY COMPOSITE
0.8
0
9
HEMPEPOXY COMPOSITE
0.8
0
8
HEMPEPOXY COMPOSITE
0.8
0
7
HEMPEPOXY COMPOSITE
0.8
0
6
HEMPEPOXY COMPOSITE
0.8
0
5
HEMPEPOXY COMPOSITE
0.8
0
4
HEMPEPOXY COMPOSITE
0.8
0
3
HEMPEPOXY COMPOSITE
0.8
0
2
HEMPEPOXY COMPOSITE
0.8
0
1
Resin Epoxy
0.8
0
Quantitative Analysis
The behaviour of FRPencased composite columns under UDL uniformly distributed axial load is determined when it is impacted at an instance. It is carried out by performing a preliminary design of seven different types of column structures and the investigation includes the given columns in thre different specified storey heights viz. 900mm, 1500mm and 2100mm. An efficient 3D finite element model for each columns prototype is modelled, and then comparison is done accordingly with different parameters such as total and directional deformation, equivalent von mises stress criteria, equivalent elastic strain, normal and shear stresses as well as the strains developed due to them. The 7 types of column structures employed in the present investigation as shown through figure 2 (ag) are as:

Concrete column of dimensions = (300×300) mm. (C)

Concrete column of dimensions = (300×300) mm with a FRP casing of 9mm thick layers. (CF)

H Section Steel column = flange (300×15)mm and web (270×10)mm. (S)

Composite steelconcrete column. (S) embedded in (C). (SC)

Composite steelconcrete column with FRP casing. 9mm layer over (SC)

Concrete column (C) with 8 nos. 12mm dia steel reinforcements. (SRC)

Reinforced concrete column with FRP casing of 9mm layup. (SRCF)
Therefore, a total of 21 cases are investigated to justify the use of Hemp Fibre reinforced polymer jackets. The Impact Force as applied in all the cases is 5 x 106 N.
(a) (b) (c) (d)
(e) (f) (g)
Fig.2 (ag): Different types of column models in the problem
A uniaxial compressive force is applied on the column from the top at an instance providing an impact to the structure. This uniformly distributed load provides a direct compressive stress to the structure and thus, deformation and strains are produced in the element. These parameters are thoroughly defined and plotted to compare the efficiency and strength of these different types of columns. The deformed structural models with their respective maximum and minimum values are shown in Fig.3 (ag).

Concrete Column C (b) Concrete + FRP Column CF

(c)SteelReinforced Concrete Column SRC (d) SteelReinforced Concrete Column + FRP SRCF
(e) Steel HSection S (f) Steel HSection+ Concrete Column SC
(g) Steel HSection+ Concrete + FRP Column SCF
Fig.3 (ag): Deformed Structural models of the seven column cases.


RESULTS AND DISCUSSION
The main purpose of the study was to determine the effects of axial compressive load on the structural steelreinforced concrete and composite columns. To achieve this, an analysis on the concept of finite element method was conducted with all appropriate parameters and data was acquired. This data was then analyzed to provide insights into encased composite column behaviour under uniformly distributed impact loading. Factors explored include von mises stress calculation, various forms of stresses and strains (shear and normal) and deformations. Observations are made with the help of plots of reduced data and graphics of the column behaviour.
Further, graphs are plotted against their comparable column cases, and their significance is presented.
The total deformation & directional deformation are general terms in finite element methods. Directional deformation can be put as the displacement of the system in a particular axis or a defined direction whereas, Total deformation is the vector sum all directional displacements ofthesystems.
VonMises stress criterion is considered the best way for design engineers to predict the strength of a specific material. Using this information, a structural engineer can say if his designs will fail. It definitely will, if the maximum VonMises stress value formed in the material is greater than strength of material. It works on the basis of Distortion energy theory.
Table 3: Obtained parametric values under different conditions.
PARAMETERS
Concrete Column (C)
Concrete + FRP (CF)
Steel Reinforced Concrete ( SRC )
Steel Reinforced Concrete + FRP (SRCF)
Column Height (mm)
900
1500
2100
900
1500
2100
900
1500
2100
900
1500
2100
Total Deformation (mm)
5.8605
7.7729
9.7857
5.1297
7.1464
9.2922
22.05
32.662
43.245
21.568
31.84
42.089
Directional Deformation (mm)
0.9324
0.84866
0.78576
0.6343
0.5818
0.5335
2.3103
2.2423
2.1334
2.1356
2.0659
1.8518
Equivalent (Von Mises) Stress (MPa)
2948
1956.7
1425.6
419.37
365.5
330.21
50742
71203
79758
47724
49968
38026
Equivalent Elastic Strain (mm/mm)
9.8266 e002
6.5224 e002
4.752 e
002
6.38 e 002
5.6353 e
002
5.1272 e
002
0.4954
0.4116
0.44524
0.4853
0.5127
0.48605
Normal Stress (MPa)
576.98
376.59
273.2
114.49
94.66
80.904
5614
3263
5884.4
5073
5343.1
6578.1
Normal Elastic Strain (mm/mm)
2.2382 e002
1.4718 e002
1.0763 e002
1.5511 e002
1.2012 e
002
7.5673 e
003
9.2766 e002
0.1257
0.13428
6.6436e
002
8.8977 e002
6.9844 e002
Shear Stress (MPa)
422.72
278.18
200.48
156.8
138.52
125.82
13450
15264
16980
11734
13412
14378
Shear Elastic Strain (mm/mm)
3.3254 e002
2.1883 e002
1.5771 e002
8.8912 e002
7.8551 e
002
7.1349 e
002
0.5087
0.4858
0.49246
0.4665
0.59059
0.5711
PARAMETERS
HSection Steel (S)
HSection Steel+ Concrete (SC)
HSection Steel + Concrete + FRP (SCF)
Column Height (mm)
900
1500
2100
900
1500
2100
900
1500
2100
Total Deformation (mm)
3.986
6.5383
9.1255
4.6842
6.5059
8.4544
1.8792
3.1334
4.3886
Directional Deformation(mm)
0.2588
0.2473
0.2456
0.28375
0.30167
0.25877
9.2457
9.2402e
002
9.1592e002
2940.6
1675.3
2234.5
12271
8460
6868.3
815.6
714.01
719.29
Equivalent Elastic Strain (mm/mm)
1.4703 e002
8.3767 e003
1.118 e002
0.40903
0.28202
0.22896
5.1779e003
4.3319e
003
3.9492e003
Normal Stress (MPa)
794.43
242.22
258.13
662.84
563.86
596.32
72.056
63.251
51.543
Normal Elastic Strain (mm/mm)
4.4314 e003
2.4919 e003
4.0764 e003
1.7192e
002
1.302e002
6.608e003
1.2037e003
1.1588e
003
1.11e003
Shear Stress (MPa)
594.38
459.31
353.43
931.88
549.82
661.16
221.48
198.56
182.43
Shear Elastic Strain (mm/mm)
7.7269 e003
5.971 e003
4.5947 e003
7.3308e
002
4.3253e
002
5.2011e
002
2.8793e003
2.5812e
003
2.3716e003
Comparison between Concrete (C) and Concrete +FRP (CF) Columns
Total and directional deformation
The plots in fig.4 (a) and (b) clearly depicts how even after increasing the surface area of impact with marginal 9mm of FRP casing, the total deformation and the directional deformation along the planar axis is less than the original concrete column. This shows how the casing increases the compressive strength of the structure.
Equivalent vonmises stress and elastic strain
The graph fig.4 (c) shows that the encased column induces less magnitude of stress for the same compressive force applied. This in turn shows how FRP confinement will lead to less strain formation, thus deformation will be minimized. Here, plot in fig.4 (d) shows that the strain produced will be marginally less in short columns than their Nonencased counterpart while the same concept will
fail in longer and much slender columns for the same load, with a unidirectional FRP casing.
Normal stress and normal elastic strain
The plots (e) and (f) in fig.4 depicts the advantageous behaviour of FRP casing, as the magnitude of normal stress and strain, thus produced is less than that in original column without confinement.
Shear stress and shear elastic strain
The plots in fig.4 (g) and (h) depict the stress and strain produced in the structure. While it manages to induce less amount of stress in the structure, the strain so formed surpasses the barrier and leads to shear failure. This shear failure is observed due to the orientation of the FRP casing. Had it been orthogonally or multidirectionally oriented, the casing would have been able to withstand this stress.
Total Deformation (mm)
Total Deformation (mm)
12
10
8
6
C
4
CF
2
0
900 1500 2100
Column height (mm)
1
Directional Deformation (mm)
Directional Deformation (mm)
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
C CF
900 1500 2100
Column Height (mm)

(b)

Eq Elastic Strain (mm/mm)
Eq Elastic Strain (mm/mm)
1.20E01
3500
Eq VonMises Stress (MPa)
Eq VonMises Stress (MPa)
3000
2500
2000
1500
1000
500
0
C CF
900 1500 2100
Column Height (mm)
1.00E01
8.00E02
6.00E02
4.00E02
2.00E02
0.00E+00
C CF
900 1500 2100
Column Height (mm)
(c) (d)
700
Normal Stress (MPa)
Normal Stress (MPa)
600
500
400
300
200
100
0
900 1500 2100
Column Height (mm)
2.50E02
Normal Elastic Strain (mm/mm)
Normal Elastic Strain (mm/mm)
2.00E02
1.50E02
C 1.00E02
CF
5.00E03
0.00E+00
C CF
900 1500 2100
Column Height (mm)
(e) (f)
450
Shear Stress (MPa)
Shear Stress (MPa)
400
350
300
250
200
150
100
50
0
900 1500 2100
Column Height (mm)
1.00E01
Shear Elastic Strain (mm/mm)
Shear Elastic Strain (mm/mm)
9.00E02
8.00E02
7.00E02
6.00E02
5.00E02
C 4.00E02
CF 3.00E02
2.00E02
1.00E02

E+00
C CF
900 1500 2100
Column Height (mm)
(g) (h)
Fig.4. Graphical plots of parameters between Concrete (C) and Concrete +FRP (CF) Columns
Comparison between SteelReinforced Concrete (SRC) and SteelReinforced Concrete + FRP (SRCF) Columns
Total and directional deformation
The plots in fig.5 (a) and (b) depicts how after increasing the surface area of impact with 9mm of FRP jacket, the total deformation and the directional deformation along the planar axis is less in SRCF than the SRC column. This shows how the casing increases the compressive strength of the structure.
Equivalent vonmises stress and elastic strain
The graph (c) in fig.5 shows that the encased column SRCF induces less magnitude of stress for the same compressive force applied, as the height of column is increased. This in turn shows how FRP confinement will lead to less strain formation, thus deformation will be minimized. The second plot (d) in fig.5 shows that the strain produced will be marginally less in short columns than their Non encased counterpart while the same concept will fail in longer and much slender columns for the same load, with a unidirectional FRP casing.
Normal stress and normal elastic strain
The graph (e) in fig.5 shows how normal stress acts with a steelreinforced concrete column structure. In a short
column, the presence of the confining retrofit proves to be beneficial whereas when the column height is increased, the stress values soars above their counterparts due to the brittle nature of the composite. The Resin matrix in any composite is responsible for this brittle nature and is a topic of further research. The plot in fig.5 (f) depicts the advantageous behaviour of FRP casing when it boils down to calculating strain and deformation in the structure, as the magnitude of normal strain produced in SRCF is less than that in original column SRC.
Shear stress and shear elastic strain
The plots (g) and (h) in fig.5 depict the stress and strain produced in the structure. While it manages to induce less amount of stress in the structure, the strain so formed surpasses the barrier and leads to shear failure. Still, the casing is able to resist shear failure in short columns, but fails when slenderness or height is increased. This shear failure is observed due to the orientation of the FRP casing. Had it been orthogonally or multidirectionally oriented, the casing would have been able to withstand this stress.
50
Total Deformation (mm)
Total Deformation (mm)
45
40
35
30
25
20
15
10
5
0
900 1500 2100
Column Height (mm)
SRC SRCF
2.5
Directional Deformation (mm)
Directional Deformation (mm)
2
1.5
1
0.5
0
1 2 3
Column Height (mm)
SRC SRCF

(b)
Eq VonMises Stress (MPa)
Eq VonMises Stress (MPa)
90000
80000
70000
60000
50000
40000
30000
20000
10000
0
900 1500 2100
Column Height (mm)
SRC SRCF
0.6
Eq Elastic Strain (mm/mm)
Eq Elastic Strain (mm/mm)
0.5
0.4
0.3
0.2

0
900 1500 2100
Column Height (mm)
SRC SRCF
(c) (d)
7000
Normal Stress (MPa)
Normal Stress (MPa)
6000
5000
4000
3000
2000
1000
0
900 1500 2100
Column Height (mm)
SRC SRCF
1.60E01
Normal Elastic Strain (mm/mm)
Normal Elastic Strain (mm/mm)
1.40E01
1.20E01
1.00E01
8.00E02
6.00E02
4.00E02
2.00E02

E+00
900 1500 2100
Column Height (mm)
SRC SRCF
(e) (f)
18000
Shear Stress (MPa)
Shear Stress (MPa)
16000
14000
12000
10000
8000
6000
4000
2000
0
900 1500 2100
Column Height (mm)
SRC SRCF
0.7
Shear Elastic Strain (mm/mm)
Shear Elastic Strain (mm/mm)
0.6
0.5
0.4
0.3
0.2
0.1
0
900 1500 2100
Column Height (mm)
SRC SRCF
(g) (h)
Fig.5 (ah): Graphical plots of parameters between SteelReinforced Concrete (SRC) and SteelReinforced Concrete + FRP (SRCF) Columns.
Comparison between Concrete (C), Steel (S), Steel +Concrete (SC) and Steel +Concrete +FRP (SCF) Columns
Total and directional deformation
The plots in fig.6 (a) and (b) proves how even after increasing the surface area of impact with marginal 9mm of FRP casing, the total deformation and the directional deformation along the planar axis is the least in SCF than their basic counterparts C, S or SC. This shows how the casing increases the compressive strength of the structure.
Equivalent vonmises stress and elastic strain
The graphs (c) and (d) in fig.6 shows that the encased column induces less magnitude of stress for the same compressive force applied. This in turn shows how FRP confinement will lead to less strain formation, thus deformation will be minimized. The same concept is applied on strain produced in the column. The amount of strain produced is marginally less in the FRPencased
column, than its counterparts. Thus, deformation will be slightly less.
Normal stress and normal elastic strain
The plots (e) and (f) in fig.6 proves that the FRP casing provides a positive impact on the stress and strain produced due to a normal force. Both of these parameters are less in SCF column when compared to its counterparts, C, S and SC.
Shear stress and shear elastic strain
The plots fig.6 (g) and (h) depicts the stress and strain produced in the structure. The FRP casing in the SCF column is able to cut down the Shear stress and strain with a marginal difference, thus leading to less probability of deformation and shear failure.
Total Deformation (mm)
Total Deformation (mm)
12
10
8
6
4
2
0
900 1500 2100
Column Height (mm)
C S SC
SCF
1
Directional Deformation (mm)
Directional Deformation (mm)
0.8
0.6
0.4
0.2
0
900 1500 2100
Column Height (mm)
C S SC
SCF

(b)

Eq VonMises Stress (MPa)
Eq VonMises Stress (MPa)
14000
12000
10000
8000
6000
4000
5.00E01
Eq Elastic Strain (mm/mm)
Eq Elastic Strain (mm/mm)
4.00E01
C 3.00E01 C
S 2.00E01 S
SC 1.00E01 SC
2000
0
900 1500 2100
Column Height (mm)
SCF 0.00E+00
Column Height (mm)
SCF
(c) (d)
1000
Normal Stress (MPa)
Normal Stress (MPa)
800
600
400
200
2.50E02
Normal Elastic Strain (mm/mm)
Normal Elastic Strain (mm/mm)
2.00E02
C 1.50E02 C
S 1.00E02 S
SC 5.00E03 SC
0
900 1500 2100
Column Height (mm)
SCF 0.00E+00
Column Height (mm)
SCF
(e) (f)
1000
Shear Stress (MPa)
Shear Stress (MPa)
800
600
400
200
0
900 1500 2100
Column Height (mm)
C S SC
SCF
8.00E02
Shear Elastic Strain (mm/mm)
Shear Elastic Strain (mm/mm)
7.00E02
6.00E02
5.00E02
4.00E02
3.00E02
2.00E02
1.00E02
0.00E+00
900 1500 2100
Column Height (mm)
C S SC
SCF
(g) (h)
Fig.6 (ah): Graphical plots of parameters between Concrete (C), Steel (S), Steel + Concrete (SC) and Steel + Concrete + FRP (SCF) Columns
5 CONCLUSIONS
It is apparent from results and comparisons that confinement effect of composite columns provides enhancement of strength and ductility up to a certain column height. The strain produced in the structure increases with respect to the increase in slenderness ratio. Different forms of composite columns indicate different behavior when it comes to shear or normal strains. Column with embedded steel Hsection shows better performance with FRP casing while a steelreinforced concrete column fails to do so. In present study numerical model is proved to be very successful as with respect to the results obtained under different conditions. Therefore, the same can be used in under different conditions such as loading type, size of columns, nonelasticity of concrete or the resistance or ductility of columns. The present numerical model is proved to be successful for the safe design and economical strengthening of concrete columns using natural FRP.
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Marinella Fossetti, Francesco Basone, Giuseppe DArenzo, Giuseppe Macaluso, and Alfio Francesco Siciliano, FRP Confined Concrete Columns: A New Procedure for Evaluating the Performance of Square and Circular Sections, Advances in Civil Engineering, vol. 2018, 2018, pages 15.

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Haider Al Abadi, Hossam Abo ElNaga, Hussein Shaia, Vidal PatonCole, refined approach for modelling strength enhancement of FRPconfined concrete, Construction and Building Materials, Volume 119, 2016, Pages 152174.

Stephen Pessiki and Kent A. Harries and Justin T. Kestner and Richard Sause and James M. Ricles , Axial Behavior of Reinforced Concrete Columns Confined with FRP Jackets,Journal of Composites for Construction, volume 5, 2001 , pages 237245.

J.J. Zeng, G. Lin, J.G. Teng, L.J. Li, Behavior of largescale FRP confined rectangular RC columns under axial compression, Engineering Structures Volume 174, 2018, Pages 629645.

JunJ ie Zeng, YongChang Guo, WanYang Gao, JianZhang Li, JianHe Xie, Behaviour of partially and fully FRPconfined circularized square columns under axial compression, Construction and Building Materials, Volume 152,2017,Pages 319332.

Marijn R. Spoelstra and Giorgio Monti ,FRPConfined Concrete Model, Journal of Composites for Construction, volume 3, pages 143150,1999.

Laura De Lorenzis and Ralejs Tepfers , Comparative Study of Models on Confinement of Concrete Cylinders with Fiber – Reinforced Polymer Composites, Journal of Composites for Construction},volume 7 pages 219237 ,year2003.

Silvia Rocca and Nestore Galati and Antonio Nanni , Review of Design Guidelines for FRP Confinement of Reinforced Concrete Columns of Noncircular Cross Sections, Journal of Composites for Construction, volume 12, pages 8092year 2008,

Rami Eid, Patrick Paultre, Compressive behavior of FRP confined reinforced concrete columns, Engineering Structures, Volume 132, 2017, Pages 518530,

Nadeem A. Siddiqui, Saleh H. Alsayed, Yousef A. AlSalloum, Rizwan A. Iqbal, Husain Abbas, Experimental investigation of slender circular RC columns strengthened with FRP composites, Construction and Building Materials, Volume 69, 2014, Pages 323334.

Marinella Fossetti, Francesco Basone, Giuseppe DArenzo, Giuseppe Macaluso, and Alfio Francesco Siciliano, FRP Confined Concrete Columns: A New Procedure for Evaluating the Performance of Square and Circular Sections, Advances in Civil Engineering, vol. 2018, 2018, pages 15.

Thomas Vincent, Togay Ozbakkaloglu, Influence of shrinkage on compressive behavior of concretefilled FRP tubes: An experimental study on interface gap effect, Construction and Building Materials, Volume 75, 2015, Pages 144156.

Manal K. Zaki, Investigation of FRP strengthened circular columns under biaxial bending, Engineering Structures, Volume 33, Issue 5, 2011, Pages 16661679.

J.L. Pan, T. Xu, Z.J. Hu, Experimental investigation of load carrying capacity of the slender reinforced concrete columns wrapped with FRP, Construction and Building Materials, Volume 21, Issue 11, 2007, Pages 19911996.

Haider Al Abadi, Hossam Abo ElNaga, Hussein Shaia, Vidal PatonCole, Refined approach for modelling strength enhancement of FRPconfined concrete, Construction and Building Materials, Volume 119, 2016, Pages 152174