Design and construction principle of steel concreat composite column final

COMPOSITE COLUMN
Design and construction principle of composite column
SEPTEMBER 19, 2017
HABTAMU BASHU
Submitted to ATO LEUL MEBRATE

DESIGN AND CONSTRUCTION
PRINCIPLE OF STEEL AND CONCREATE COMPOSITE COLUMN sep 19
1 | P a g e EIABC 4TH YEAR internship program
Abstract
Composite steel-reinforced concrete columns are a very important application of composite
structures, and they have wide application in high-rise buildings. Columns and compression members can
be designed which are from a normal weight concrete of the strength classes C20/25 to C50/60 and from
the steel grades S235 to S460. Columns of high-rise buildings must resist the high values of normal forces.
A higher degree of resistance can be obtained with the use of high-strength concrete. If high-strength
concrete (HSC) is used in a composite column, the resistance will be greater than the resistance of the
column with the use of normal strength concrete; respectively, we will achieve a smaller size of the cross-
section. Former construction methods could be studied in all materials, e.g. wood, steel and concrete
construction, as they are more graphical to students of architecture. Furthermore, elder methods and
procedures to determine the inner forces of statically systems could be studied, to gain the capacity of
simple control of computer calculations.
Key words: Composite, Column, Concrete, Steel

ACKNOWLEDGEMENT
In the name of GOD, the most Gracious and the most Merciful.
I sincerely expresses my deepest gratitude to the Almighty.
First and foremost, I would like to express thank to my supervisor Mr. Leul mebrate for his guidance
in this project. I would like to thank commercial bank of Ethiopia construction project office for hosting
me in their huge project for three months helping me do this project. I, sincerely, express my deep sense of
gratitude to CBE project officer Eng. Hana for her help in providing me books researches and guiding me.
I would also like to thank all AAIT consultant team especially Mr. Mohamed, Miss Tinbit and Miss.Loza
for their helpful guidance. The last but not the list I would like to appreciate my family for their support
throughout this experience.

List of fig page no
Fig1.1 Ericsson Building ……………………………………………………………………….....9
Fig 1.2 the combination of concrete cores, steel frame…………………………………………….9
Fig 2.1 Typical Cross Sections of Composite Columns……………………………………..…....12
Fig2.2 Encased composite column……………………………………………………………….12
Fig 2.3 Concrete filled steel column……………………………………………………………...13
Graph 1 Comparison of Weight of Structure……………………………………….....................20
Graph 2 Comparison of Time Period………………………………………………………...…...20
Graph 3 Comparison of Axial Force…………………………………………………………...…21
Graph 4 Shear Force in Column (longitudinal Direction)………………………………………...21
Graph 5 Comparison of bending moment (Longitudinal Direction)…………………………...…22
Graph 6 Base Shear Comparison………………………………………………………………....22
Graph 9 stress – strain curve of concrete ……………………………….…………………...……29
Graph 8 typical stress – strain curve of steel……………………………………………...………29

Table of content page no
1. Chapter one
1.1 Introduction………………………………………………………………………………....7
1.1.1 CBE New Head office construction project ……………………………………………....................8
1.1.2 China state construction Eng. Corporation (CSCES).…………………….......................8
1.1.3 General .……………………………………………………………………..................8
1.2 Back ground study of the project…………………………………………………..................9
1.2.1 Construction history of composite Columns……………………………………….….10
1.3 The main objectives of the project………………………………………………….............10
2. Chapter two
2 Literature review…………………………………………………………….……...………11
2.1. Conceptual definition of composite column………………………….…….……….…11
2.2. Types of composite column…………………………………………............................11
2.2.1 Concrete encased steel columns………………………………....……...……………12
2.2.2 Concrete-filled steel tubular composite columns…………………….…………...…..13
2.3. Research on Steel-Concrete composite Columns………………….………..…............14
2.4. Conclusions…………………………………………………………………................19
3. Chapter three..
3.1 Comparisons between steel – concrete
Composite olumn and RCC project ……………………………………………………20
3.1.1 Weight of structure………………………………………………..….…..…..............20
3.1.2 Time Period and Frequency ……………………………………….…………...….....20
3.1.3 Axial Force in column, Shear Force in Column and Bending Moment….…………...21
3.1.4 Base Shear ………………………………………………………………....………...22
3.1.5 Cost of Structure…………………………………………….……………...………...23
3.2 CONCLUSION………………………………………………………………….………...23
3.3 Properties of materials……………………………………………….………………….....24
3.4 CBE project structural steel element………………………………….……………............25
3.5 Reinforced Concrete…………………………………………………….……………...….26
3.5.1 Advantage of reinforced concrete……………………………………………………..27
3.5.2 Disadvantages of Reinforced Concrete ……………………………………….............27
3.6 Advantage of composite column ………………………………………………………….27
3.7 Dis advantages of composite column ………………………………………………….....28
3.8. Effect of high strength concrete on composite column…………………………………...29
4. Chapter four
Composite column design …………………………………………………………………....30
4.1 General ……………………………………………………………………………........30
4.2 STEPS IN DESIGN………………………………………………………………….....30
Conclusion …………………………………………………………………………………....….32
Recommendations …………………………………………………………………………….....33
Reference ………………………………………………………………………………………...34

LIST OF ABBREVIATIONS
CBE Commercial bank of Ethiopia
FT Concrete filled tube
FEC Fully encased composite
HSC High strength concrete
PEC partially encased composite
SD Standard deviation
SHSC Super high strength concrete
SRC Steel reinforced column

Chapter one
Introduction
1.1.1 Commercial bank of Ethiopia New Head office construction project
The new head quarter building of commercial bank of Ethiopia is located in the central business district
of Addis Ababa. The building will became an important land mark in Addis Ababa, Ethiopia is currently
the tallest building in east Africa. The new head quarter building will make outstanding contribution to the
dynamics sky line of Addis Ababa. The project planning area of CBE is 18307.83 m2
, total floor area is
164429.39m2
among them the area on the ground is 112749.77m2
and basement area is 51679.62m2
. The
project includes the tower building (G+48), conference center (G+7), and commercial center (G+ 8)
corridor and basement (-4). The height of the tower building, conference center and commercial center
205.825m, 45, 42.9 respectively.
1.1.2 China state construction Eng. Corporation (CSCES)
China Construction has inherited all superior assets and corporate culture of CSCEC, with its business
covering housing construction, international contracting, real estate development and investment
infrastructure construction and investment, prospecting and design
China Construction is China’s largest construction and real estate conglomerate and biggest building
work contractor. It is the largest transnational construction company in the developing countries and the
top home builder in the world, taking the long lead of China’s international contracting business. China
Construction is well known in the world for undertaking super high-rise, grand scale, cutting-edge and
novel projects and has built up a great number of landmark projects in China and around the world. Such
business concept and brand image of China Construction as “Providing Excellent Services across all
Continents with Superior Quality as the Top Priority” is universally acknowledged and commended.
This huge project contractor is CSEC, CSCEC has a lots of working experience in other huge projects
in other countries like Hong Kong and Macao, West and Central Africa, Southern Africa, North Africa,
Europe, Central Asia, North America, Middle East and Southeast Asia (new building for Congo
(Brazzaville) BSCA bank, Djibouti Doha multi-function port, phase one of Libya 20,000 sets residential
building project, Tunisia general hospital, Egypt Hosni Mubarak school, Laos lung prabang conch cement
factory and dam construction… etc.) also here in Addis Ababa E.g. African Union, the new national
stadium, national oil.
Award recognitions
 China Tien-yow Jeme Civil Engineering Prize (Tien-yow Jeme Prize) is a civil engineering
scientific award approved by the Ministry of Science and Technology and affirmed by the Ministry
of Construction.
 Luban Prize, initiated in 1987, is the top prize for quality in China’s construction projects,
representing the advanced level of quality for the domestic construction works

1.1.3 General
Composite column is a structural member that uses a combination of structural steel shapes,
pipes or tubes with or without reinforcing steel bars and concrete to provide adequate load carrying capacity
to sustain either axial compressive loads alone or a combination of axial loads and bending moments. In a
composite column both the steel and the concrete sections resist the external loading by interacting together
by bond and friction. Composite columns are constructed providing structural steel inside concrete or
concrete inside the structural steel. These columns are being used worldwide for the construction of high
rise buildings since it can reduce the size of the columns in the building and increase the usable space of
the floor plan. In addition, composite column enhances the overall rigidity of the building and provides
significant shear resistance to strong earthquakes and other lateral loads. The paper presents a simplified
method of construction method and highlight of the design approach of composite columns.
Composite columns may be practically used for low and high-rise buildings. For the low-rise
buildings, steel columns are often encased in concrete for the sake of appearance or for protection of steel
from fire, corrosion, and from vehicle in garages. For high-rise buildings, composite columns are stiffer
than non-composite steel columns. The size of composite columns is often considerably smaller than is
required for reinforced concrete columns to support the same loads. The high tensile strength and ductility
are the main advantages of steel members. They can also be used for erection of the building and resisting
all construction loads. However, concrete members can increase the compressive strength and stiffness to
assist the resistance of service loads. The choice of a steel, concrete, or composite system for any particular
project depends not only on system efficiency, material availability, cost, construction methods, and labor,
but also on planning, architectural, and aesthetic criteria. It is thus impossible to reach definitive conclusions
solely on the basis of a structural system evaluation.

1.2 Back ground study of the project
1.2.1 Construction history of composite column Columns
The construction history of composite columns can be divided into four periods:
1) Research started early in the beginning of the 20th century
2) A first climax of application about 1930, followed by
3) A period of oblivion, until
4) A revival of research and application from the 1950s until today.
Although composite columns of concrete and steel were rarely used from the end of World War II
until the early s, research had started a long time before 1970, at the beginning of the 20th century.
Combining of these materials had a number of motivations, steel columns were often encased in concrete
to protect them from fire, while concrete columns were combined with structural steel as a reinforcement.
Until 1932, more than 1 500 tested specimen in Europe and North America were reported by
Emperger at the first IABSE Congress in Paris (1932), among those were 138 tests done by himself.
Emperger complained about the lack of design rules for composite columns in Europe and 1023 mentioned
the American “Standard Specifications for Concrete and Reinforced Concrete” of 1924, which gave explicit
formulas for both composite columns and steel columns encased in concrete, a vital advantage for the
application of composite columns during the 1920s and 1930s in tall buildings in Chicago. In Germany, it
took until 1943 to apply composite columns in the German concrete regulations DIN 1045. Emperger´s
efforts in the development of composite columns are described in (Eggemann 2003a).
After a period of oblivion, research in the field of composite construction was intensified during the
1950s and several design methods were developed. As a consequence, Koppel’s proposal for concrete filled
steel columns - first published (1935) - were taken into account for German steel regulations DIN 1050 in
1954. For today’s Euro code 4, the design method of Roik and his team was considered, developed in the
1970s (Roik, Bergmann, Bode and Wagenknecht 1975; 1976). This was taken as a basis for the proposed
simplified design method.
fig 1.2 the combination of concrete cores, steel frame Fig1.1 Ericsson Building, Vienna, 1913 (Emperger 1913)

1.3 The main objectives of the project
To introduce steel-concrete composite column members in construction; to explain the composite
action of the two different materials and to show how the structural members are used, particularly in
building construction, the advantage and dis advantage of the steel – column composite column. The project
is expected to provide an insight of the role of composite column in construction. The main drive for this
project was that the composite structures are not exercised that much as far as my knowledge the
commercial bank of Ethiopia head quarter building is the first one to use it in our country. This project has
mainly focused on the composite columns construction principle and a little bit of the design.

Chapter two
2 Literature review
2.1. Conceptual definition of composite column
A steel – concrete composite column is conventionally a compression member in which the steel
element is a structural steel section. There are three types of composite columns used in practice which are
Concrete Encased, Concrete filled, and Battered Section.
2.2. Types of composite column
There are three types of composite column based on their concrete encasement and steel section type
types of composite columns, those with steel section encased in concrete and those with steel section in-
filled with concrete are commonly used in buildings. Basic forms of cross-sections representative of
composite.
Composite Columns type
Three different types of composite columns are principally in use, see Figure 12:
 Concrete encased steel columns (a)
 Concrete filled steel tubes and (c and d)
 rolled section columns partly encased in concrete (b)
Fig 2.1 Typical Cross Sections of Composite Columns

2.2.1 Concrete encased steel columns
Concrete-encased steel composite columns have become the preferred form for many seismic-
resistant structures. Under severe flexural overload, concrete encasement cracks resulting in reduction of
stiffness but the steel core provides shear capacity and ductile resistance to subsequent cycles of overload
They are commonly used. The concrete encasement has often been considered as only fire and corrosion
protection for the steel. However, in recent years, lateral and sometimes longitudinal reinforcement has
been added to the concrete encasement, and the resultant strength of the steel and concrete interacting has
been used for structural purposes. A steel shape, encased in concrete, may be thought of as reinforcement
for the concr
Fig2.2 Encased composite column
Load-bearing and have many advantages over plain steel or concrete. The term composite column, as
applied in architecture, may refer to a column of the Composite order. The steel backbone of a composite
column lends its increased strength and resistance to buckling.

2.2.2 Concrete-filled steel tubular composite columns
Concrete-filled steel tubular columns have been used for earthquake-resistant structures, bridge piers
subject to impact from traffic, columns to support storage tanks, decks of railways, columns in high-rise
buildings and as piles. Concrete-filled steel tubes require additional fire-resistant insulation if fire protection
of the structure is necessary. Because of the increased use of composite columns, a great deal of theoretical
and experimental work has been carried out.
They have been popular for use as individual column elements. The confined concrete fill increases
the axial load resistance but has little effect on the flexural resistance. For that reason, it is unlikely that
these columns would be a good choice for a moment resisting frame. Filling the tube with concrete will
increase the ultimate strength of the member without significant increase in cost. The main effect of
concrete is that it delays the local buckling of the tube wall and the concrete itself, in the restrained state, is
able to sustain higher stresses and strains than when in the unrestrained state.
Fig 2.3 Concrete filled steel column.

2.3. Research on Steel-Concrete composite Columns
Extensive experimental research works were carried out on FEC and CFT columns by previous
investigators. Experimental study on composite columns started in the year of 1905 for concentric axial
load. Analytical and theoretical studies stared from the year of 1976. Recently, the numerical models were
developed to determine the behavior and strength of FEC columns. Successive sections will focus on the
experimental, analytical and numerical investigations on FEC columns under various conditions of loading.
Bridge and Roderick (1978) and Eggemann (2003) reported that Emperger (1907) tested three steel
columns to determine their buckling loads in year 1907. Successively, he carried out more than 1000 tests
on composite columns in Europe and about 570 tests in North America from 1907 to 1932. He also
distinguished different types of composite columns. Finally, the researchers published a design formula to
determine the ultimate capacity of composite columns.
Virdi and Dowling (1973) investigated experimentally nine square FEC columns for eccentric axial load.
The objective of the test was to determine the experimental and analytical ultimate load carrying capacity
of these FFC columns. The columns had a 254 mm× 254 mm square cross section reinforced with a 152.4
mm × 152.4 mm × 23.4 kg/m structural steel section encased in 50.8 mm of concrete and four 12.7 mm
diameter rebar's, one at each corner and with a 19.05 mm clear cover. The variables were the length,
eccentricity along major and minor axis. These columns were pin-ended composite columns tested under
axial loads and biaxial bending. Authors reported that the analytical results could predict the experimental
results with good accuracy.
Matsui (1979) conducted research work on the behavior of concrete-encased columns subjected to
eccentric axial load. The objective of this study was to observe the effects of slenderness on ultimate
capacity and failure modes. Three specimens were constructed with normal strength concrete with square
cross-section (160 mm × 160 mm). The length of these columns was 924 mm, 2309 mm and 3464 mm. The
structural steel section was H-shaped 100 × 100 × 6 × 8 mm used in all the FEC columns. The specimens
had concrete cube strengths 18.5, 21.4 and 22.5 MPa and structural steel yield stresses were 306, 298, 304
MPa, in these columns, respectively. The longitudinal reinforcement bars were 6 mm in diameter and the
transverse reinforcement bars were 4 mm in diameter. The yield stress of the reinforcing bars (fyr) was 376
MPa in all the columns. The relative slenderness ratios of the specimens were 0.26, 0.66 and 1.29. The
author determined that the experimental capacity of these columns were 996, 974 and 874 kN, respectively.
He reported that the ultimate capacity of these columns decreased with the increase of slenderness ratio.
Author also presented the failure modes of these columns and reported that comparatively less slender
columns failed due to concrete crushing, followed by structural steel yielding and more slender columns
failed by flexural buckling.
Morino et al. (1984) experimentally investigated the elasto-plastic behaviour of steel reinforced concrete
(SRC) columns subjected to biaxial eccentric compression load. The purposes of this study were to observe
the reduction of ultimate capacity and failure behaviour due to changes in eccentricity angle and slenderness
of FEC columns. The column specimens had a 160 mm × 160 mm concrete square cross section encasing
rolled steel H section of 100 × 100 × 6 × 8 mm. The columns were divided in four groups as per slenderness
ratios and designated as A4, B4, C4 and D4. The load was applied for two different eccentricities (40 mm
and 75 mm) on these columns. Each eccentric axial load was applied from five different angles (0; 300,
450, 600 and 900). Three experimental parameters varied for the test columns were, the slenderness ratio,
the eccentricity and the angle location of the applied load. Effect of eccentricity, angle between load point
and major axis, and slenderness ratio on the load-deflection behaviour and the maximum load carrying

capacity were investigated. The ultimate load carrying capacities of these columns are reduced by
about 35% when eccentricity is changed from minor axis to major axis. Authors reported that a sharp peak
appears on the load-deflection curve of a short column because of concrete crushing. The P-delta effect was
more pronounced in a long column and a gradual unloading took place.
Munoz et al. (1997) carried out experimental study on the behaviour of biaxially loaded concrete- encased
composite columns. The composite column specimens were one short and three slender, with square cross
section,(63.5 mm × 63.5 mm). Each specimen consisted of Ishaped structural steel section encased by
concrete and additionally reinforced with four longitudinal reinforcements as corner bars. The slenderness
ratio of the column with L/r = 42.7was designated as MC1. The slenderness ratios of other three columns
were L/r = 64, was designated as MC2, MC3 and MC4, respectively. The overall length of the specimens
was 8130 mm for the short column (MC1) and 12200 mm for the long columns (MC2, MC3 and MC4).
The average concrete compressive strength were 36.77, 30.97, 25.83 and 27.51 MPa for columns MC1,
MC2, MC3 and MC4, respectively. Strain gauges were fixed at the surface of these test specimens to
determine the axial strain and the curvatures with respect to the main bending axis of the column. The main
variables considered in the experimental investigation were concrete compressive strength fcu, tensile
strength of reinforcing steel, slenderness ratio, and eccentricity of the applied load. The effects of the
eccentrically applied axial compressive force, load-deflection and moment-curvature behavior on the
maximum load capacity of a composite column were examined. The axial load capacities were 28.17, 26.48,
29.06 and 22.03 kN for these columns MC1, MC2, MC3 and MC4, respectively. The failure modes of these
columns were observed during the experimental test. Hairline cracks were started on these columns MC1,
MC2, MC3 and MC4 at 50%, 30%, 40% and 40% of the maximum load, respectively. The test results were
compared with the analytical results of the maximum load capacity obtained from a numerical analysis.
The comparative results indicated that the analytical method and computer program used to model and
analyze the composite column specimens (i.e. numerical analysis) could accurately predict the maximum
load capacity and deformation behavior of a pin-ended biaxialy loaded concrete-encased steel column with
axial compressive load in single curvature bending.
Chen and Yeh (1996) carried out extensive experimental studies to determine the ultimate capacity of FEC
columns with different shaped structural steel. Ten short columns were constructed with three different
shapes of the structural steel section with normal strength concrete. The shapes of the structural steel
sections used in the specimens were I, H and cross shaped. All the H-shaped steel section were more similar
to the wide-flange section, while the I-shaped section had a narrow flange. The specimens had square cross-
sections of 280 mm × 280 mm and a constant nominal length of 1200 mm. The specimens had concrete
cylinder strengths varying from 26.4 to 29.8 MPa and a structural steel yield stress of 296 to 345 MPa. The
longitudinal and transverse reinforcement bars were 16 mm and 8mm in diameter. Three different spacings
of transverse reinforcement (35 mm, 75 mm and 140 mm) were used to observe the effect of transverse
spacing on overall capacity of columns. The author reported that the columns constructed with cross-shaped
structural steel sections took comparatively more load than the other shaped ones. This happened as the
confining effect was more in the FEC columns constructed with cross shaped structural steel. The ultimate
load carrying capacity also increased when the transverse reinforcement spacing decreased. The rates of
load increment for the closer spacing of transverse reinforcement were comparatively higher in the columns
constructed with H-shaped structural steel. Tsai et al. (1996) experimentally determined the behavior of
axially loaded steel reinforced concrete columns. Ten short columns were constructed with cross shaped
structural steel section with normal strength concrete. These ten (10) specimens were labeled from SRC1
to SRC10. The specimens had square cross-sections of 280 mm × 280 mm and a constant nominal length

of 1200 mm. The specimens had concrete cylinder strengths varying from 21.3-26.3 MPa and a steel yield
stress of 296-345 MPa. The longitudinal and transverse reinforcement bars were 16 mm and 8 mm in
diameter. Three different spacing of transverse reinforcement (100 mm, 140 mm and 190 mm) were used
to observe the effect of transverse spacing on overall capacity of columns. The author reported that the
ultimate load carrying capacity increased when the transverse reinforcement spacing decreased. The rate of
the load increment was about 2%.
Shih et al. (2013) carried out study on axial strength and ductility of square composite columns with two
interlocking spirals. The axial compressive capacity and load– displacement behavior of composite columns
confined by two interlocking spirals were experimentally and analytically investigated. The innovative
spiral cage used for a square column was fabricated by interlocking a circular spiral and a star-shaped spiral
to enhance the confinement effect for the core concrete. Eight full-scale square composite columns were
tested under monotonically increased axial compression. Experimental results demonstrated that, with
significant savings of the transverse reinforcement, the composite columns confined by two interlocking
spirals achieved excellent axial compressive strength and ductility. It revealed that the spirally reinforced
concrete column achieved better load carrying capacity and behavior than the rectilinearly tied reinforced
concrete column, although the amount of the spirals was less than that of the rectilinear hoops. Moreover,
an analytical model was developed to take into account the concrete confinement due to the structural steel
in addition to the transverse reinforcement and distributions of the longitudinal bars. The analytical results
accurately predicted the axial compressive capacity and load–displacement behavior of the specimens
Lia-Hai Han et al. (2011), have investigated the tensile behaviour of CFST section considering
parameters such as steel ratio and type of concrete. Tensile behaviour of CFST section was examined by
experimentally as well as developing a finite element model. The study found that the tensile strength of
CFST section is more than the hollow steel tube and it was further increased by filling SFRC concrete into
steel tube. Researchers had also proposed a simplified formula for calculating tensile strength of CFST
section and it gives good agreement between calculated and tested results.
Jingfeng Wang, Na Zhang (2017), This paper investigated performance of circular concrete filled steel
tubular (CFST) column to steel beam joints with blind bolts. Four monotonic loading tests were conducted
on the flush or extended end plate joints to circular CFST columns with blind bolts. A nonlinear finite
element (FE) modeling study on the circular CFST column joints under static loading was developed, in
considering contact interaction, material model and analysis steps etc. The accuracy of the FE models was
examined by the experimental results in the field of moment rotation relationships and failure modes.
Massive parametric analysis was utilized to explore the effects of axial level, bolt diameter and anchorage
length ratio etc. on the ultimate moment capacity and the initial stiffness of the novel connections. The test
and 3D elasto plasticity numerical analysis results indicated that the circular CFST column joints could be
regarded as semi-rigid and partial or full strength. Effective methods including anchorage and stiffening
strengthening were also discussed in this paper to promote the engineering application of circular
CFST column joints with blind bolts.

Compressive behavior
Dundar et al. (2006) conducted an experimental study on the behavior of reinforced and concrete-encased
composite columns subjected to biaxial bending and axial load. The primary objective of this investigation
was to examine the ultimate strength capacity and load-deflection behavior of short and slender reinforced
concrete columns. The experimental results were compared with the ultimate capacities obtained
theoretically. Theoretical results were calculated using various stress–strain models for the materials done
by previous authors. The experimental program included fifteen (15) reinforced concrete columns. Five
specimens were short square (100 mm × 100 mm) tied columns (C1–C5) with 870 mm length. Seven
specimens were slender square tied columns (C11-C14, C21–C23) with two different sizes. Other three
specimens were L-shaped section slender tied columns (LC1–LC3). The columns groups (C11-C14) and
(C21-C23) were 100 mm × 100 mm and150 mm × 150 mm square in sizes, respectively. Ultimate capacity
of these reinforced concrete columns were determined experimentally for eccentric axial load and compared
with calculated theoretical results. A computer program was developed based on these theoretical
calculations. The ultimate capacity was determined using this computer program for the tested FEC
columns. The authors reported that the theoretical results could predict the experimental results for different
cross section of reinforced and composite column members with good accuracy.
Y. F. Yang, L. H. Han (2012), have examined the behavior of CFST under partial compression by
considering different parameters, namely cross sectional shape, length to diameter ratio and partial
compression area ratio. The study was carried out by testing twenty-six specimens of CFST by varying the
above parameters and their behavior was also verified by developing a finite element model using
ABAQUS software. The study shows that the behavior of partial compressed CFST section is similar to the
behavior of fully compressed CFST section. Also, it is possible to predict strength of partial compressed
CFST section using mathematical model proposed by researchers.
Farid Abed et al. (2013), studied the compressive behavior of circular CFST column filled with different
concrete grades and varying D/t ratios. The experimental results of study were compared with analytical
method proposed by various codes namely EC-4,ACI-318,AISC-2005and AS. From these studies
researchers have concluded that for higher D/t ratio, reduction in compressive
strength of CFST section occurs due to less confinement. The study also shows that for the higher D/t ratio
there is less deviation observed in experimental and analytical results. Experimental results of this study
were also verified using ABAQUS software and there is found to be a good agreement in-between both
results.
Kalingarani et al. (2014), investigated the compressive behavior of slender CFST columns by
analytically using various available codes, namely EC4, ACI-318 and AISC- 2005.The study was carried
out by varying diameter to thickness (D/t) and length to width (L/D) ratio. Analytical results
obtained by using codal method indicates that for an increased D/t ratio keeping diameter constant,
compressive strength of CFST section was decreased due to less confinements also reduction in
compressive strength occurs for increased L/D ratio due to slenderness effect.

Bond Strength
Prion and Boehme (1994) conducted an investigation on concrete filled steel tubes in bending. The results
indicated that specimen dissipated a significant amount of energy with only a slight decrease in strength
when the loading cycle progressed. The strength of CFSTs during subsequent cycles was not greatly
affected by the slip between the two materials. The beam specimens showed a loss of stiffness due to a lack
of bond and the cracking of the concrete after the first cycle.
Hunaiti (1994) investigated on fifteen battened composite specimens to find the bond strength between
steel and concrete at the age of five years. The result of this investigation showed that the bond strength at
the age of five years was about two and half times greater than of that the age of one year. This was mainly
due to rusting of steel at the surface of contact with 20 concrete. It resulted in the increase of the mechanical
keying due to micro irregularities and thus enhanced the bond between the two materials.
Hunaiti (1996) conducted an experimental investigation on composite action of foamed and lightweight
aggregate concrete. Thirty-six push out tests were performed on concrete-filled hollow steel sections in
square and circular shapes. It was found that the strength of bond in composite sections was significantly
affected by the type of concrete. However, it appeared that the type of concrete did not influence the load-
slip behavior as all the tested specimens produced similar load-slip curves. Lightweight aggregate concrete
showed higher resistance to push-out loads and thus had better composite action. Moreover, bond reduction
due to age in normal concrete specimens is higher than that of lightweight aggregate concrete specimens.

2.4. Conclusions
With the advent of steel and reinforced concrete, the concepts in construction has changed from one
of securing stability to that of stressing the materials to the optimum values. This has resulted in very light
structures compared to the pre-19th century constructions. This has been made possible by eliminating in
the newer materials, the short comings of poor tensile strength of the traditional materials. In order to
critically evaluate the research works done in the area of concrete filled steel tubular and fully encased
composite columns, a detailed review of literature in the field of CFT & FEC column has been undertaken.
From the review of literature presented in this chapter it has become clear that extensive experimental
investigations were carried out on strength and failure modes of short and slender FEC and CFT columns
with normal strength of concrete (21 MPa to 35 MPa) and structural steel (250 MPa to 350 MPa) for
concentric, eccentric and biaxial loading conditions. Studies on FEC columns using various percentages of
structural steel are limited. Behavior of FEC columns with high and ultra-high strength materials has not
been explored completely. Effects of several geometric parameters such as column slenderness ratio,
structural steel ratio, load eccentricity ratio and tie spacing on the strength and ductility of high strength
FEC columns need to be explored. Most of the available codes on composite columns do not include the
capacity prediction equations for high strength materials. In most of the codes, the upper limit for the
strength of concrete is 70 MPa and for structural steel is 525 MPa. Therefore, the code specified guidelines
and design equations for composite columns need to be extended to incorporate the effects of high and
ultra-high strength materials. Experimental investigations on FEC & CFT columns with various structural
steel percentages and concrete strength are therefore required. However, it is not possible to get a complete
understanding of the influences of various components from experimental investigations only due to the
high cost and time requirement for full scale testing. Therefore, finite element models are also required that
can accurately predict the behavior of FEC and CFT columns under various combinations of geometric and
material properties.

Chapter three
3.1 Comparisons between steel – concrete composite column and RCC project
3.1.1 Weight of structure
Weight of any structure is depends upon its components and material used in construction. Weight should
be kept as low as possible to reduce the earthquake effect. In order to find out dead weight and make it a
lighter structure we have studied the weight of all structural members in composite steel concrete and RCC
building. From the following figure it is seen that composite structure is having less weight by 35.05 %
comparing to RCC.
Graph 1 Comparison of Weight of Structure
3.1.2 Time Period and Frequency
It is observed that for both the structures time period continuously decreases and correspondingly the
frequency increases from 1st node to 12th node. The time period of composite structure is more than RCC
structure and at the same time frequency is more in RCC structure than Composite structure. The time
period of composite structure is increased by 19 % to 25% and on the other hand frequency is decreased by
22% to 24%. The reduction in stiffness of composite structure results in increase of time period and decrease
in frequency.
Graph 2 Comparison of Time Period

3.1.3 Axial Force in column, Shear Force in Column and Bending Moment
The result shows that the axial force in maximum composite column is less than RCC column. An
average reduction of 10% to 12% is seen in axial force of composite column.
Graph 3 Comparison of Axial Force
The comparison of shear force is shown in Graph 4. It can be observed that the shear force in maximum
composite column is less than RCC column in both the direction. Accept in column C17 in transverse
direction and in column C14 in longitudinal direction shear forced is more in composite structure. In
longitudinal direction the shear force is reduced by 25% to 29% and in transverse direction shear force is
reduced by 33% to 37%
Graph 4 Shear Force in Column (longitudinal Direction)
Analysis result shows that the bending moment in composite column section is less than RCC column
section. In column C14 in longitudinal and C17 in transverse the bending moment is increased by 24% and
18% respectively. An average reduction of 35% to 45% is seen in bending moment of composite column
than R.C.C. column in longitudinal direction.

Graph 5 Comparison of bending moment (Longitudinal Direction)
3.1.4 Base Shear
As the base shear is the horizontal reaction to the earthquake forces and horizontal forces results from the
story weight. Story weight includes the self-weight of the structure also; hence in the reinforced cement
concrete model the self-weight is seems to be the more and hence maximizing the earthquake forces which
results in the maximum base shear. As we have the static formula for base shear and base shear is the direct
function of the seismic weight therefore naturally base shear is more in the case of RCC structure. The
analysis is carried out as per code IS:1893-2002 and the results of base reactions directly shows that base
shear in longitudinal and in transverse direction is less in composite structure than RCC structure. The base
shear is the basic parameter for deciding the earthquake resistant structure. To make the structure safe, the
base shear should be kept as low as possible. The base shear in Composite structure is reduced by 34.46%
in X Direction and 46.6% in Y direction.
Graph 6 Base Shear Comparison

3.1.5 Cost of Structure
The cost comparison is made on the basis of material cost and results shows that the cost of composite
structural elements is more than RCC structural elements. Material cost of composite structure is increased
by 31.63 %. On the other hand the construction process of composite structure is much faster than
conventional RCC structure. So when we consider the time required for construction, the composite
structure is always preferable than conventional RCC structure. Speedy construction facilitates quicker
return on the invested capital and benefits in terms of rent.
3.2 CONCLUSION
 The dead weight of Composite structure is found to be 30 % to 35% less than RCC structure and
hence the seismic forces are reduced by 30% to 35%. As the weight of the structure reduces it
attract comparatively less earthquake forces than RCC structure. This will add to further reduction
in axial forces, shear forces and bending moment as compared to RCC structure. As the weight of
structure is reduces the size of foundation also reduces which leads to saving in foundation cost.
 The axial force in composite column is found to be 7% to 9% less than RCC columns in linear
static analysis. This reduction in axial force reduces the size of column and ultimately saves the
material and its cost.
 The shear force in composite column is reduced by 25% to 29% in longitudinal direction and 33%
to 37% in transverse direction at 1st story. A significant reduction in shear force in both the
direction is seen in composite column member.
 The bending moment in composite column in linear static analysis reduces by 58 % to 68% in
longitudinal direction. The reduction in bending moment reduces the size of column.
 It is also seen that if the secondary beams are provided below the composite slab, then the composite
structure gives more stiffness than RCC structure. Increased stiffness of composite structure results
in reduction of lateral of lateral displacement of composite structure.
 The schedule of design of composite and RCC structure shows that the composite members requires
much reduced dimensions than that of RCC members. The reduction in dimension of composite
column results in providing more usable area.
 Due to high rates of steel one may find composite construction a little bit costly at the initial stage,
but due to its speedy construction work the project can be completed as early as possible than RCC
construction. In addition to this, reduced dimensions of beams and columns in composite
construction leads to reduction in dead weight of the structure which ultimately helps in reduction
of the cost of foundation.

3.3 Properties of materials
Information on the properties of structural steel, concrete, and reinforcement is readily available.
Only that which has particular relevance to composite structures will be given here. For the determination
of the bending moments and shear forces in a beam or framed structure (known as ‘global analysis’) all
three materials can be assumed to behave in a linear – elastic manner, though an effective modulus has to
be used for the concrete, to allow for its creep under sustained compressive stress. The effects of cracking
of concrete in tension, and of shrinkage, can be allowed for, but are rarely significant in buildings.
Rigid-plastic global analysis can sometimes be used, despite the profound difference between a
typical stress-strain curve for concrete in compression, and those for structural steel or reinforcement, in
tension or compression, that is illustrated in Fig. 1.1. Concrete reaches its maximum compressive stress at
a strain of between 0.002 and 0.003, and at higher 20 strains it crushes, losing almost all its compressive
strength. It is very brittle in tension, having a strain capacity of only about 0.0001 (i.e. 0.1mm per meter)
before it cracks. The figure also shows that the maximum stress reached by concrete in a beam or column
is little more than 80% of its cube strength. Steel yields at a strain similar to that given for crushing of
concrete, but on further straining the stress in steel continues to increase slowly, until the total strain is at
least 40 times the yield strain. The subsequent necking and fracture is of significance for composite
members only above internal supports of continuous beams, for the useful resistance of a cross-section is
reached when all of the steel yields, when steel in compression buckles, or when concrete crushes.
Resistances of cross-sections are determined (‘local analysis’) using plastic analysis wherever
possible, because results of elastic analyses are unreliable, unless careful account is taken of cracking,
shrinkage, and creep of concrete, and also because plastic analysis is simpler and leads to more economical
design. The higher value of γ M that is used for concrete, in comparison with steel (Table 1.2) reflects not
only the higher variability of the strength of test specimens, but also the variation in the strength of concrete
over the depth of a member, due to migration of water before setting, and the larger errors in the dimensions
of cross-sections, particularly in the positions of reinforcing bars. Brief comments are now given on
individual materials.

3.4 CBE project structural steel element
The main structural material steel
1. the steel used in steel reinforcement concrete column are Q3458
2. Steel shall detected by tension test bending test charpy v – test and smelting test analysis. The ratio of
measured yield strength of the steel material to measured tensile strength should not exceed 0.85. The
steel material should have significant yield terrace and an elongation no less than 20%the steel material
should provide excellent welding performance and adequate impact toughness. The content of Sulphur,
phosphorus and carbon should be welding structural steel.
3. When the steel plate thinness (T) is greater than or equal to 40mm, tension test should be carry out at
the thickness direction. The reduction of the thickness direction should satisfy: when 40 t 60, the
requirements of Z15, when 60 T 100, the requirement of z25.
4. Bolt
 The grade of bolt is c, its material is Q235.
 Except for additional noted, the high strength bolt is 10.9 level tor – shear bolt.
5. T – Bolt
 Tension strength of T - bolt should be not less than 400n/m m2.
 The diameter of t –bolt is 19mm, the light of T – Bolt is 100mm.
 When the t bolt was welding, welding porcelain ring should be placed on the steel web to ensure
the welding quality of the T-Bolt.
Construction requirements for steel structural member
1. The drawing are only steel structure working drawing, detail design company should draw
construction detail when drawing detail, the position of beam bars, column bars should be carefully
checked, to ensure the holes on steel webs are correct.
2. According to the design document and construction detail, production process should be
established. The book should include management and quality insurance system process
equipment: qualification of welders and inspectors proof; all kinds of project inspection forms so
on.
3. When lofting, the necessary welding shrinkage allowance should be kept, in addition, the arch
component should be ensured that material size is very accurate.
4. Materials in the process of cutting and correction should be ensured that no damage the material
organization the material strength shall be not affected by the point and scars.
5. Steel shall be made by mechanical processing.
6. Steel frame installation unit should use column perforation from, the segmentation of the steel
columns is refer to the drawing of the detailed design company.
7. The diameter of concrete aggregate should be less than 1/3 of the thickness of steel protective layer
and should be less than 25mm.

8. The high strength bolt hole is made by drilling hole, and its precision is H12 level. The allowable
deviation of the aperture and distance between the aperture shall be in accordance with the
requirements of the following table.
9. Welding of steel flung and web should use automatic or semi-automatic gas cutting for cutting,
10. The friction surface of high strength bolt connection member should be processed, and the anti-
slip coefficient should be 0.45 in the production of steel structure, the anti-slip coefficient should
be carried out.
11. Steel member should be correctable by mechanical or limited (line heating or point heating)
heating. When heating is performed, make Shure the maximum heating temperature and Colling
method will not damage steel material.
12. The end milling plane allowable deviation should meet the requirement bellow
3.5 Reinforced Concrete
Reinforced concrete consists of steel and concrete which are combined together to act as a composite
material where steel helps in taking both compression and tension whereas concrete can withstand only
compression. RCC is a structural material which is widely used in many kinds of
structures. It is involving with steel even though economically designed and executed. Advantages of
Reinforced Concrete

3.5.1 Advantage of reinforced concrete
1. Reinforced concrete has larger compression as compared to most other materials used for
construction apart from good in tension.
2. It has greater resistance to fire than steel and ability of resisting fire for a extended period of time.
3. It has lengthy service life with very little maintenance cost.
4. It can appear to take the shape needed, made largely used in pre-cast structural elements.
5. It yields stiff members with least apparent deflection.
6. Yield strength of steel is nearly fifteen times the compressive strength of structural concrete and is
higher than hundred times its tensile strength.
3.5.2 Disadvantages of Reinforced Concrete
1) It requires necessity of mixing, casting and curing of concrete, all of which it influence the final
strength of concrete.
2) The price of the forms used to cast concrete is relatively up.
3) It has less compression to steel where the ratio is about 1:10 depending on material which leads to
big sections in beams or columns of multi-story buildings. Cracks are developed in concrete due to
shrinkage and in the application of live loads.
3.6 Advantage of composite column
For a number of decades, structural steel shape have been used in combination with plain or reinforced
concreate. Originally, the encasing concrete was used to provide only fire and corrosion protection for the
steel, with no consideration given to its strengthening effects. More recently, however, the development
and increasing popularity of composite frame construction has encouraged designers to include the strength
of the concrete in their calculation.
Composite column may be partially used for low rise and high rise buildings. For the low rise
buildings. For the low- rise ware house, parking garage and so on the steel column are often encased in
concrete for the sake of appearances or protection from fire, corrosion, and vehicles. If we are going to
encase the steel in concrete anyway, we may as well take advantage of the concrete and use smaller steel
shapes.
Fore high rise buildings the size of composite columns often are considerably smaller than the required
for reinforced – concrete columns to support the same loads. The result with composite column design are
applicable saving of valuable floor space. Closely spased composite steel – concrete columns connected
with spandrel beam may be used around the outside of high – rise buildings to resist lateral loads by the
tabular concept. Very large composite columns are sometimes placed on the corner of high rise buildings
to increase lateral resisting moments. Also, steel section embedded within reinforced concrete shear wall
may be used in the central core of high buildings. This also ensures a greater degree of precision in the
construction of the core.
With composite construction, the bare steel section support the initial loads, including the weight of
the structure, the gravity, lateral load occurring during construction, and the concrete later cast around the
w shapes or inside the tube shapes. The concrete and steel are combined in such a way that the advantage
of both material are used in the composite section. For instance the reinforced concreate enables the building
frame to more easily limit swaying or lateral deflections. At the same time, the light weight and strength of
the steel shapes permits the use of smaller and lighter foundation.

 Increased strength for a given cross sectional dimension.
 Increased stiffness, leading to reduced slenderness and increased buckling resistance.
 Good fire resistance in the case of concrete encased columns.
 Corrosion protection in encased columns.
 Significant economic advantages over either pure structural steel or reinforced Concrete
alternatives.
 Identical cross sections with different load and moment resistances can be produced by varying
steel thickness, the concrete strength and reinforcement. This allows the outer dimensions of a
column to be held constant over a number of floors in a Building, thus simplifying the construction
and architectural detailing.
 Erection of high rise building in an extremely efficient manner.
 Formwork is not required for concrete filled tubular sections.
With the use of composite columns along with composite decking and composite beams it is possible to
erect high rise structures in an extremely efficient manner. There is quite a vertical spread of construction
activity carried out simultaneously at any one time, with numerous trades working simultaneously. For
example
 One group of workers will be erecting the steel beams and columns for one or two Story at the
top of frame.
 Two or three story’s below, another group of workers will be fixing the metal Decking for the
floors.
 A few story’s below, another group will be concreting the floors.
 As we go down the building, another group will be tying the column reinforcing bars in cages.
 Yet another group below them will be fixing the formwork, placing the concrete into the column
mold’s etc.
 3.7 Dis advantages of composite column
As described in the preceding section, composite column have several important advantage. They
also have a few disadvantage. One particular problem with their use in high rise buildings is the difficulty
of controlling their rates and amount of shortening in relation to the shear wall and, perhaps, adjacent
plain columns. The accurate estimation of this items is made quite difficult by different types and stage of
construction activities going on simultaneously over a large building stories.
If composite columns are used around outside of a high – rise building, and plain steel section are
used in the building core (or if we have shear wall), the creep in the composite section cane a problem. The
result may concrete floors that are not very level. Some erectors make very care full elevation measurement

at column splice and then try to make appropriate adjustment with steel shims to try to even out the
deference between measured elevation and computed elevation.
Another problem with composite columns is the lack of knowledge available concerning the
mechanical bond between the concrete and the steel shapes. This particular important for the transfer of
moments through beam – column joint. It is feared that if large cyclical strain reversals where to occur at
such a joint there could be a server breakdown of the joint.
3.8. Effect of high strength concrete on composite column
High strength steel has several advantages in its applications to tall buildings. Improvement in ductility
of high strength steel has enhanced the research activities in this area. High strength and low weight are
beneficial in seismic design with seismic response being reduced by the low weight of a structure. The
stiffness in concrete increases with its characteristic strength. Higher strength concrete has an effective
initial modulus of elasticity that increases roughly in proportion to the second or third root of the
compressive strength and density. Typical stress– strain curves of steel and concrete are given in Figs.
bellow, respectively. Rangan and Joyce and O’Brien and Rangan have reported the results of tests on
eccentrically loaded slender steel tubular columns filled with high-strength concrete as high as 115 MPa.
The eccentricity of the applied compressive load was equal at both ends, and the columns were subjected
to single curvature bending. All specimens failed at mid-height due to crushing of concrete in the
compression zone. In all specimens, the extreme fiber tensile strains at failure did not reach the yield strain
of steel. The calculated ultimate loads of Rangan and Joyce were found to underestimate the experimental
results with the maximum difference of 68%. Similar experiments were carried out to examine the behavior
of thin-walled circular steel tubes filled with ultra-high strength concrete (115 MPa) [18]. The test
specimens had an effective diameter to thickness ratio between 60 and 200 and a length to
diameter ratio of 3.5. The specimens were tested under axial and eccentric loading. It was shown that
unloading response of high strength concrete is rapid and may exhibit axial strain reversal, the snap-back
process. Further test have been conducted to examine the potential enhancement in strength and possible
improvement in ductility due to confinement of high strength concrete.
Graph 7 stress – strain curve of concrete Graph 8 typical stress – strain curve of steel

Chapter four
COMPOSITE COLUMN DESIGN
4.1 General
As in other structural components, a composite column must also be designed for the Ultimate Limit State.
For structural adequacy, the internal forces and moments resulting from the most unfavorable load
combination should not exceed the design resistance the composite cross-sections. While local buckling of
the steel sections may be eliminated, the reduction in the compression resistance of the composite column
due to overall buckling should definitely be allowed for, together with the effects of residual stresses and
initial imperfections. Moreover, the second order effects in slender columns as well as the effect of creep
and shrinkage of concrete under long term loading must be considered, if they are significant. The reduction
in flexural stiffness due to cracking of the concrete in the tension area should also be considered.
4.2 STEPS IN DESIGN
Design Steps for columns
1. List material properties such as fy, fsk, (fck)cy, Ea, Es, Ec
2. List the composite column specifications and the design value of forces and moments.
3. List sectional properties Aa, As, Ac, Ia, Is, Ic of the selected section.
Design checks
I. Evaluate plastic resistance, Pp of the cross-section from equation,
Pp = Aa fy /Ja +Dc Ac (fck)cy / Jc + As fsk / J s
II. Evaluate effective flexural stiffness, (EI)ex and (EI)ey, of the cross- section for short term loading
from equations,
(EI)ex =EaIax + 0.8 EcdIcx + EsIsx
(EI)ey =EaIay + 0.8 EcdIcy + EsIsy
III. Evaluate non-dimensional slenderness, and from equation,

Ppu = Aafy + DcAc(fck)cu + Asfsk (Ja = J c = Js= 1.0 ;
IV. Check the resistance of the section under axial compression about both the axes. Design against
axial compression is satisfied if following conditions are satisfied:
P < Fx Pp
P < Fy Pp
Where

Conclusion
Composite construction, particularly that using profiled steel sheet ng, allows rapid construction.
The weight of steelwork required in composite construction is sign faintly less than if the materials were
used independently. There is no need for expensive false work and formwork because the steel beam is able
to sustain the self-weight of steel and concrete, by itself f or with the assistance of a few temporary props.
Timber formwork can be replaced by precast concrete elements or profiled steel sheeting. The
aforementioned advantages present a very strong argument for the use of composite beams in buildings.
They are more significant, however, for medium to long spans than for short spans. The main disadvantage
of composite construction is the need to provide connectors at the steel-concrete interface. Another minor
drawback is that it is somewhat more complicated than other methods to design and construct. This
drawback is particularly relevant to continuous structures and bridges. However, it is far outweighed by the
significant advantages that can be gained.

Recommendations for Future project
The following recommendations are made for future investigations.
o Further experimental investigations on composite columns with high and ultra-high
strength materials are required to have complete understanding of the effects of these
materials on strength and failure behavior of these columns.
o The current numerical model was developed for monotonic loading conditions only Effects
of cyclic loadings may be addressed in future research work.
o The numerical model may be extended to incorporate the effects of geometric
imperfections and residual stresses on the behavior of composite columns.
o The effects of the dynamic loading on the behavior of composite columns with high
strength materials may be investigated.
o Further improvement to the finite model can be done by simulating the interface between
steel and concrete.
o Further numerical investigations are required to study the effect of high strength materials
on composite columns.
o Future research work is required to propose modifications to the code provided guidelines
for the construction of P-M diagram for composite columns with high and ultra-high
strength materials.

Reference
 Almusallam, T.H., and Alsayed, S. H. (1995). “Stress-strain relationship of normal, high strength
and light weight concrete.” Magazine of Concrete Research, 47 (107), 39-44.
 American Concrete Institute. (2014). “Building code requirements for structural concrete (ACI
318-14) and commentary.” ACI 318-14, Farmington Hills, MI.
 American Institute of Steel Construction. (2010). “Specification for structural steel buildings.” An
American National Standard, ANSI/AISC 360-10, Chicago.
 Amin, A. M. M., Fadel, A. M., Gaawan, S. M., and Darwish, R. A. (2016). “Assessment the limit
of steel core area in the encased composite column.”
 Int. Journal of Engineering Research and Applications, 6(1- 3), 72-78. Bangladesh National
Building Code (1993). BNBC, Dhaka, Bangladesh. Barr, B., and Lee, M. K. (2003).
 “Modelling the strain-softening behavior of plain concrete using a double-exponential model.”
Magazine of Concrete Research, 55 (4), 343-353. Begum, M., Driver, R. G. and Elwi, A. E. (2007)
 “Finite element modeling of partially encased composite columns using the dynamic explicit
solution method” Journal of Structural Engineering, ASCE, 133(3), 326-334. Bridge, R. Q., and
Roderick, J. W. (1978).
 “Behavior of built-up composite columns.” Advanced Design of Composite Steel-Concrete
Structural element by Dr. D. R. Panchal -ISSN : 2248-9622, Vol. 4, Issue 7( Version 2), July 2014,
pp.124-138 [2] ANSI/AISC 360-05 An American National Standard Specification for Structural
Steel Buildings March 9, 2005.
 Comparative Analysis of RCC and Steel-Concrete Composite (B+G+ 11 Storey) Building Mr.
Nitish A. Mohite, Mr.
 P.K.Joshi, Dr. W. N. Deulkar IJSR, Volume 5, Issue 10, October 2015 ISSN 2250-3153
 Composite Structures of Steel and Concrete (Beams, slabs, columns, and frames) for buildings
Third Edition by R.P. JOHNSON (2004)
 Eurocode 4: Design of composite steel and concrete structures

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