Comparative Study of Structure Using Composite Members And Conventional Members

Charuhas K. Karalkar Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 5, Issue 5, ( Part -5) May 2015, pp.88-92
www.ijera.com 88 | P a g e
Comparative Study of Structure Using Composite Members And
Conventional Members
Charuhas K. Karalkar*, Dr. Uttam B. Kalwane **
*( PG Student, Department of Civil Engineering, Dr. D Y Patil School of Engineering & Technology,
Lohegaon, Savitribai Phule Pune University, Pune – 411014)
** (Guide and Principal at Dr. D Y Patil School of Engineering & Technology, Lohegaon, Savitribai Phule Pune
University, Pune – 411014)
ABSTRACT
There are different methods of construction for building structure. The most popular conventional structures used
are reinforced cement concrete structures, pure steel structures and Timber Structures. In the modern age the
rapid growth in population and continuous influx of people from rural to metros; buildings are constructed on a
large scale and with great Architectural requirement.
In this paper a new type of structure is introduced which involves use of composite members. To reduce the
construction time, material quantity and cost the composite members are used. The composite members here
mean use of steel sections as structural steel along with timber. Here by using composite members for
miscellaneous Architectural building, lot of saving has been done in material, construction time and cost. It saves
approximately 20-25% cost of structure if conventional type is used. Composite members used are Structural
steel and solid timber compare to conventional steel or RCC members.
Keywords - Conventional type frame structure, composite member frame structure, Light frame structure,
timber steel composite, Cost Analysis
I. INTRODUCTION
The most important and most frequently
encountered combination of construction materials is
that of steel and concrete, with applications in multi-
storey commercial buildings and factories, as well as
in bridges. These materials can be used in mixed
structural systems in composite structures where
members consisting of steel and concrete act together
compositely. Here, in this paper use steel and timber
hybrid structure is focused. In conventional practice
RCC / structural steel members are used in building
structures. But due to Architectural requirement
cladding is used in some cases to give aesthetic
looks. This increases cost of structure. Hence, if we
use composite material then, it saves a lot of material,
time and ultimately costing. Benefits of using steel in
timber include increase in tensile capacity, seismic
performance, and cost savings.
These essentially different materials are
completely compatible and complementary to each
other. Steel and timber materials are used to form
composite members which increase the serviceability
of structure during earthquake and wind prone areas.
Steel has more thermal expansion than the wood.
This forms ideal combination of strength with the
timber efficient in compression and the steel in
tension. By using steels connections will allow
timber buildings to survive and remain serviceable
after earthquakes, reducing death tolls as well as
repair and business interruption costs.
The extent to which the components of a
building structure should embody all the steel
construction, be constructed entirely in reinforced
concrete, in timber construction, or be of composite
construction depends on circumstances. However
engineers are increasingly designing composite and
mixed building systems of structural steel and
reinforced concrete or structural steel and timber to
produce more efficient structures when compared to
designs using either material alone. Timber and steel
composite members mainly use for light frame
structures.
II. OBJECTIVE OF THE STUDY
The light frame structures (Timber Structures)
are more susceptible to damage due to earthquake
and heavy wind. Due to this fact the modern
techniques of construction involves use of moment
resisting frames. The use of composite members
suggested in this report may prove to be seismic and
wind resistant over conventional technique used for
such type of buildings.
The main objective of the present paper is to
capture the modified performance of the building
using composite member against regular members
and its cost comparison with conventional steel/
timber building structure. For this one miscellaneous
light frame building structure located near Pune is
considered. It is observed that the structure with
purely steel structure may have more efficient than
timber structure, only when the overall form of
RESEARCH ARTICLE OPEN ACCESS

building is regular and it is possible to use bracing at
least along the longer direction without hampering
the aesthetics of building. In India mostly buildings
are irregular in shapes due to which aesthetic
requirements of building cannot be fulfilled by only
steel construction. Hence, a comparative study of
Structural Steel and composite member construction
is carried out in this report.
III. CHOICE OF MATERIALS
1. Structural Materials
Nowadays basic framing materials for the
building construction are steel, concrete and wood.
Availability of material, cost, adequate knowledge of
design and construction, maintenance and
modification are some of influencing factors in
selecting the material of construction. Here, we are
considering steel and timber material due to aesthetic
requirement of structure. Both the materials have
their own advantages and limitations. Combining
steel and wood will increase the seismic performance
of the structure. Wood has a high strength to weight
ratio therefore wood buildings tend to be lighter than
other building types [8]. Table below shows a
comparison of strength/density ratios for some
structural materials. For pure wood this ratio is
significantly higher than other building materials [4].
Table 1: Strength/density ratios structural materials
2. Advantages of composite members
The advantages of using steel timber composite
members may be emulated as: -
a. Considerable flexibility to structure when there
is sudden increase of load by dissipating energy.
b. Ease of fabrication with skilled technique
facilitates faster erection of structure.
c. Enables easy construction schedule in congested
sites.
d. Light weight of material eases the transport at
remote located sites.
e. Satisfies requirement of long span construction,
a modern trend in architectural design.
f. Permits easy structural repair and modification
for antique structure.
g. Ideal material in earthquake prone/ heavy wind
prone locations due to high strength, stiffness
and ductility.
h. Properly designed composite steel and wood
members prevent the tensile failure mode of
wood members and have significant ductility.
i. The size of the members can be made smaller
thus increasing strength to weight ratios.
IV. TYPES OF COMPOSITE
SECTIONS
A composite column is defined as a compression
member which may either be a concrete encased
section or a concrete filled hollow section or a steel
sandwich between timber sections:-
1. Steel - Concrete Composite
According to the shape of the cross-section, there
are mainly three different types of steel concrete
composite members as:-
a. Concrete-encased sections (as shown a, b and c
below)
b. Concrete-filled hollow sections (as shown f, g
and i below)
c. Partly concreted-encased sections (as shown d
and e below).
Fig.1:- Typical cross-sections of steel -concrete
composite
2. Steel - Timber Composite
Steel – Timber composites frequently called as
flitch type me
mbers. The cross sections are as shown in figure
below. In these types of sections, mainly steel plates
pressed between different timber sections and
connected through nuts, bolts or pins. Typical cross
section is as below from betterheader [13]:-
Fig. 2:- Typical cross-sections of steel timber
composite

V. BASIC CONCEPTS IN ANALYSIS AND
DESIGN OF COMPOSITE STRUCTURE
1. Case Study: Miscellaneous light Frame Arch.
Structure
Here, for comparative study the following light
frame miscellaneous structure is considered. This
structure is situated near Pune. Below picture shows
the Architectural concept required.
Fig.3:- Architectural Concept of Building-3D view
2. Structural Concept with Conventional
Approach
STAAD Pro software is used to create model of
the structure and design by conventional approach.
The whole structure is divided into three different
parts mainly for analysis and design purpose.
Fig.4:- Structural model for conventional approach
By conventional method Structural steel
members are used and timber is used as cladding to
fulfill the Architectural requirement.
The analytical results are used to design the steel
members by using STAAD Pro Software. The
members are designed with reference to IS 800.
3. Structural Concept with composite member
Approach
By composite member approach Structural steel /
pure timber members are replaced by composite
flitch type members composed of steel as shown in
fig. 2. SCIA and REVIT software is used for
modeling and analysis of structure.
Fig. 6:- Structural model for composite structure
approach
The analytical results are used to design the
composite members by using excel spreadsheets. The
composite members are designed with reference to
EN1995-1-1:2004 [1] [2] [3].
VI. RESULTS AND COMPARISON
Quantities for Structure_By Conventional
Approach
Steel quantities
Comp
onent
Lengt
h (m)
Weigh
t (kg)
Weight
(MT) Cost
Colum
n 38.70 4547.2 4.55
INR
545,666
Beam 94.94 9910.8 9.91
INR
1,189,299
Rafter 61.57 2411.7 2.41
INR
289,408
Purlin
107.4
4 956.1 0.96
INR
114,730
Deck
Steel 6.30
INR
756,000
Conne
ctions 15% 3.62
INR
434,266
Total
27.74
INR
3,329,369
Timber quantities
Comp
onent
Lengt
h (m)
c/s
area
(m2)
Volum
e (m3) Cost
Colum
n 38.70 0.020 0.77
INR
87,075
Beam 94.94 0.020 1.90
INR
213,615
Rafter 61.57 0.020 1.23
INR
138,533
Purlin 0 0.020 0.00
INR
-
Deck
Steel 0.00
INR
-
Conne
ctions 0.00
INR
-
Total
3.90
INR
439,223
Total
Cost =
INR
3,768,592

Quantities for Structure_By composite Approach
Steel quantities
Comp
onent
Length
(m)
Weight
(kg)
Weight
(MT) Cost
Colum
n 47.00 78.5 3.69
INR
442,740
Beam 103.4 62.8 6.49
INR
779,222
Rafter 61.57 39.3 2.42
INR
289,995
Purlin 107.44 0.00
INR
-
Deck
Steel 4.20
INR
504,000
Conne
ctions 15% 2.52
INR
302,394
Total
19.32
INR
2,318,351
Timber quantities
Comp
onent
Length
(m)
c/s
area
(m2)
Volum
e (m3) Cost
Colum
n 47.00 0.020 0.94
INR
105,750
Beam 103.4 0.020 2.07
INR
232,650
Rafter 72.2 0.020 1.44
INR
162,450
Purlin 190 0.008 1.52
INR
171,000
Deck
Steel 0.00
INR
-
Conne
ctions 0.00
INR
-
Total
5.97
INR
671,850
Total
Cost =
INR
2,990,201
The above values are calculated for partial area
of the structure i.e. deck area.
This shows the total cost saving using composite
material compared to conventional method lies
between 20%- 25%.
Figure captions appear below the figure, are
flush left, and are in lower case letters. When
referring to a figure in the body of the text, the
abbreviation "Fig." is used. Figures should be
numbered in the order they appear in the text.
Table captions appear centered above the table in
upper and lower case letters. When referring to a
table in the text, no abbreviation is used and "Table"
is capitalized.
VII. CONCLUSION
The comparison of Analysis and design results
of building using composite members and steel
members shows that:-
a. Overall of costing of structure by using
composite member is reduced by 20% to 25%
than that of steel / timber members.
b. Cross-section dimension of composite members
are lesser than that of pure timber members by
5% to 15%.
c. Good fire resistance and corrosion protection are
achieved due to use of flitch type sections than
that of purely steel / timber members.
REFERENCES
Design Standard Codes:
[1] Design loads, “Code of Practice for Design
Loads for Buildings and Structures”, IS: 875
- 1987, Parts 1 to 5.
[2] IS : 1893 – 2002 Part 1, Seismic Design
base shear, “Criteria for Earthquake
Resistant Design of Structures”
[3] Member design “Design of timber
structures”, Eurocode 5: EN 1995-1-Part 1,
Part 2.
Journal Papers:
[4] Yalda Khorasani, Zhina Siadat , University
of British Columbia “Steel Timber Hybrid
Structures”, Civil 510, pg. 1-26.
[5] Richard Persaud, Dr Digby Symons,
University of Cambridge, Department of
Engineering, Trumpington Street,
Cambridge, CB2 1PZ “Design and testing of
a composite timber and concrete floor
system”, The Structural Engineer – 21
February 2006, pp. 22-30.
[6] Parvez Alam, Martin Ansell (2012); “The
Effects of Varying Nailing Density upon the
Flexural Properties of Flitch Beams”,
Journal of Civil Engineering Research 2012,
2(1), pp. 7-13.
[7] Parvez Alam (2004); “The Reinforcement of
Timber for structural applications and
repair”, University of Bath, 2004, pg. 33-
307.
[8] J D Wiesenfled (1989); “Glitches in Flitch
Beam Design”, Article, Civil Engineering,
September 1989, pg. 65-66.
Study & Theses Reports:
[9] Jobin Jacob, Olga Lucia Garzon Barragan
(2007); “Flexural Strengthening of Glued
Laminated Timber Beams with Steel and
Carbon Fiber Reinforced Polymers”,
Chalmers University Of Technology,
Master’s Thesis, pg. 13-164.

[10] Eva Frühwald, Erik Serrano, Tomi Toratti,
Arne Emilsson, Sven Thelandersson (2007);
“Design of safe timber structures”, Report,
Lund Institute of Technology, Lund
University, pg. 17-39.
Manuals and Books:
[11] Parvez Alam, Martin Ansell and Dave
Smedley (2012); “Effects of Reinforcement
Geometry on Strength and Stiffness in
Adhesively Bonded Steel-Timber Flexural
Beams”, Buildings 2012, 2, pp 231-244;
doi: 10.3390/buildings2030231.
[12] NAHB Builder’s Beam Manual, Flitch
Plate-and Steel I-Beams, Washington, D.C.
20005, 1981.
URL Link:
[13] Flitch beam types, [Online]. Available:
http://www.betterheader.com/

Comparative Study of Structure Using Composite Members And Conventional Members

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