PERPUSTARAAN UMP
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A CASE STUDY ON COMPARISON BETWEEN WOOD TRUSS AND
STEEL TRUSS FOR ROOF STRUCTURE
It•J :i uvv u h1IISJi
A thesis submitted in fulfillment of the
requirements for the award of the degree of
Bachelor of Civil Engineering
Faculty of Civil Engineering & Earth Resources
University Malaysia Pahang
JUNE 2013
ABSTRACT
Roof is an important structure found in all types of buildings regardless of
size and shape. The using of wood trusses is widely used for generations before. With
the growing construction on this time, there are other alternatives to replace wood
truss that is widely use before with steel roof truss. Both have advantages and
disadvantages respectively. Features such as workability, durability or strength, and
suitability of the building will determine the type of truss to be used. Therefore, this
study was undertaken to determine the truss suitable for use at this time. This
approach is through questionnaires, observations, and the costs associated with the
use of the two trusses. From this study, we can conclude that both have advantages
and disadvantages truss, because they both have a lot different in terms of
workability and the durability or strength. The results of research shows that the
advantages mostly on using the steel truss. This difference makes them both special
and acting as principle and the contractor or developer choice to build such a
building.
Vi
ABSTRAK
Bumbung adalah merupakan satu struktur penting yang terdapat dalam semua jenis
bangunan tanpa mengira saiz dan bentuk. Penggunaan kekuda kayu adalah
digunakan secara meluas oleh generasi sebelum ini. Dengan pembangunan yang
semakin pesat membangun pada hari i, terdapat alternatif lain untuk
menggantikan kayu yang digunakan secara meluas sebelum mi dengan
menggunakan kekuda keluli untuk struktur bumbung. Kedua-duanya mempunyai
kelebihandan kekurangan masing-masing. Ciri-ciri seperti cara pemasangan,
ketahanan atau kekuatan, dan kesesuaian bangunan itu akan menentukan jenis yang
akan digunakan. Oleh itu, kajian mi dijalankan untuk menentukan kekuda yang
sesuai untuk digunakan pada masa mi. Pendekatan mi adalah melalui soal selidik dan
pemerhatian yang berkaitan dengan penggunaan kedua-dua kekuda. Daripada
kajian mi, kita boleh membuat kesimpulan bahawa kedua-duanya mempunyai
kebaikan dan keburukan kekuda, kerana kedua-duanya mempunyai banyak
perbezaan dari segi ,ketahanan atau kekuatan dan kos. Hasil kajian menunjukkan
bahawa kelebihan kebanyakannya adalah dengan menggunakan kekuda keluli
terutamanya untuk kekuda bumbung. Perbezaan mi menjaclikan mereka kedua-dua
khas dan bertindak sebagai prinsipal dan pemithan kontraktor atau pemaju untuk
membina apa-apa bangunan.
VII
TABLE OF CONTENTS
CHAPTER TITLE PAGE
TITLE PAGE i
SUPERVISOR'S DECLARATION
STUDENT'S DECLARATION
DEDICATION iv
ACKNOWLEDGEMENT v
ABSTRACT vi
TABLE OF CONTENTS viii
LIST OF TABLES xi
LIST OF FIGURES xii
LIST OF APPENDICE xiv
INTRODUCTION I
1.1 Background of Study 1
1.2 Problem Statement 3
1.3 Objective of Study 3
1.4 Scope of Work 4
VIII
ix
2 LITERATURE REVIEW 5
2.1 Introduction 5
2.2 Wood Classification 6
2.2.1 Types of Wood 6
2.2.2 Main properties of wood 8
2.2.3 Safety Factor 9
2.3 Wood as material for roof truss structure 10
2.3.1 Truss Connection 13
2.4 Introduction of Steel Roof Truss 17
2.4.1 Type of Connection 18
2.4.2 Joint Design 18
2.4.3 Gusset Plate 19
2.5 Latest Application: Light Truss System 19
2.6 Cold Formed Steel Truss System 21
3 METHODOLOGY 23
3.1 Introduction 23
3.1.1 Literature Method 24
3.1.2 Survey Methods 24
3.1.3 Observation Method 24
3.2 Methodology Flowchart 27
x
4 RESULT AND DISCUSSION 28
4.1 Introduction 28
4.2 Compare the installation of steel and wood trusses 29
4.2.1 Installation Work 32
4.2.2 Connection work 33
4.2.3 Cutting Work 36
4.3 Comparison of Durability Wood and Steel Truss 36
4.3.1 Steel Truss 36
4.3.2 Termite attack problems 38
4.3.3 Wood easy to shrink and bend by weather 39
4.3.4 Durability and Strength of wood less 5 years 41
4.3.5 The use of immature wood 42
4.3.6 Resist to fire resistance 43
4.3.7 Weather Factor are considered 44
4.3.8 Does the Steel can sustain from corrode 46
5 CONCLUSION AND RECOMMENDATION 48
5.1 Introduction 48
5.2 Conclusion 49
5.3 Recommendation 50
REFERENCES 51
APPENDICES 53
LIST OF TABLES
TABLE NO. TITLE PAGE
2.1 Type of nails and its use in wood working 15
4.1 Data indicate the need of skilled labor at the construction
site of woodand steel trusses 30
4.2 Data comparing needed of labor at the construction site of the
project using wood trusses and steel trusses. 31
4.3 The faster installation between wood and steel trusses. 32
4.4 Data use bolts and nuts used for the two trusses. 33
4.5 Use of equipment and machinery for both trusses 35
4.6 The number of respondents who agreed that the strength of steel
more than wood 37
4.7 Respondents who agreed the wood are exposed to termite
problems. 38
4.8 Weather factor of wood shrinkage and bending terms 40
4.9 Respondents agree that the durability of wood less than 5 years. 41
4.10 Data on the use of immature wood causes wood truss failed. 42
4.11 The number of respondents agreed steel can resist the fire
resistance. 43
4.12 Weather is considered due to the shrinkage and bends 45
4.13 Steel can resist corrosive 46
A
LIST OF FIGURES
FIGURE NO. TITLE PAGE
2.1 Timber finish with defect 11
2.2 Arch Truss 12
2.3 Steep Truss 12
2.4 Flat Truss 12
2.5 Toothed Plate 14
2.7 Type of nail 16
2.8 Bolts 16
2.9 Screw 17
3.1 Building using wood truss 26
3.2 Building use steel truss 26
4.1 Pie chart percentages that needed skilled labor at
construction sites between the two trusses. 30
4.2 The pie chart showed the percentage of labor force
needed 31
4.3 Pie chart shows percentage of the faster installation time
between wood trusses and steel trusses. 33
4.4 Pie chart showing percentage use of bolts and nuts used for
the two trusses. 34
4.5 Pie chart showing the use of equipment and machinery for both
trusses 35
XII
4.6 Pie chart show the percentage of respondents who agreed that
the strength of steel is higher than wood.
4.7 Percentage of respondents agrees wood is exposed to termite
problems
4.8 Data on the percentage of weather factors in terms of wood
shrinkage and bend.
4.9 Pie Chart percentage of respondents agrees that the durability
of wood less than 5 years.
4.10 Pie chart of immature use of wood causes wood truss failed.
4.11 The pie chart on the number of respondents agreed steel
resist fire resistance
4.12 Data on the percentage of weather factors of shrinking and bend.
4.13 Data percentage of the steel can sustain from corrode.
37
39
40
41
42
44
45
47
XIII
CHAPTER 1
INTRODUCTION
1.1 Background of Study
Malaysia is rapidly developing in line with the government's vision of working
towards a developed nation by the year 2020, and government have implemented
various types of development such as schools, government offices, hospitals, factories,
housing, and so on. Accordingly, the use of roof trusses is one important foundation for
every building, regardless of whether the roof trusses are constructed of wood or steel.
Wood is a material that has long been used in the construction of the structure.
Interesting and rewarding design often produced from wood material. Apart from its use
in building structures of various shapes, wood is also used as a temporary structure for
structural concrete, brick and stone. Nowadays the wood is still an important material in
the construction, although there have been a lot of new materials created and used for
construction.
1
2
Wood also has many uses and advantages that are not may be available on other
materials, and it is more easily done by just using common hand tools. High
understanding of natural events, the advantages and disadvantages of wood is very
important in building design of timber structures. Only higher level of maturity wood is
suitable for the construction of the structure.
In general, this study was conducted to gather information on the use of roof
trusses (steel trusses). Because at present, has many housing projects using steel roof
truss structure replaces a wood truss structure is widely used before. Construction of
steel roof trusses had long been introduced in the country. Mostly, it is used in buildings
such as halls and warehouses, and also includes the housing project. The technology is
still not popular among the developers may be due to the system is still new and ourS
society still, hesitate to use it. Another possibility is steel roof truss system is considered
unsafe and may easily cause problems causing our society to consume less system.
Accordingly, a study involving the cooperation of government and private
agencies such as the Department of Public Works and construction and contractor is
intended to, provide a procedure on the difference between building structures using steel
trusses and wood trusses. Among the benefits derived from this study is to identify the
use of roof trusses and timber trusses which in terms of advantages and disadvantages as
well as the privilege of using the structure, and thus can be used as a more effective
framework in terms of building on the present and gives the developer more alternatives
in terms of construction costs, building facilities and truss structure durability.
3
1.2 Problem Statement
Roof is an important part in the construction of a building. No buildings
constructed without a roof. Thus, the components used to make the structure of the roof
trusses must be high quality and durable. As noted, the wood has a lot of problems such
as problem of termite attack, flammable, endurance less than 5 years and many more.
Previously, wood widely used as roof trusses in terms of durability it is easy to decline
compared with the use of steel. In terms of installation, the use of wood trusses is very
complicated and requires high expertise compared with steel trusses easier and save
time.
1.3 Objective of Study
i. Comparing the method of the installation of steel trusses and wood trusses.
ii. Determine the durability and strength of steel and wood.
4
1.4 Scope of Work
The buildings were selected for the study such as school buildings and
bungalows using wood and steel as the material for the roof trusses.
a) Do research on the advantages, privileges and the use of wood and steel
trusses. Analysis of the connection system is based on the size and type
current applied.
b) Visit the site and meet with the parties involved to obtain more detailed
information.
C) Collect data and display information from various aspects.
CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
Wood is a material that has long been used in the construction of the structure.
Interesting and satisfied design usually produced from wood material. In addition to
build the structure of uses in variety of shapes, wood is also used as materials for
temporary structures for structural concrete, brick and stone. Today wood remains as an
important ingredient in the construction although there were many new materials are
created and used for construction. This may be because the wood suitable as thermal
insulation and estimated 15 times more heat-resistant than concrete including the
suitability for the building that is always exposed to chemical gases (Mahyuddin Ramli,
1992). Wood is useful material that cannot be replace with other material because it is
easily handle by using common hand tools. Understanding and knowledge of weakness
of wood in the design of timber wood structure is important.
6
There are many type of wood available in Malaysia. Generally wood is divided
into two:
i. Hard wood
ii. Soft wood
Majorities' in Malaysia hard wood available because hard wood are mostly
found in tropical region like our country.
2.2 Wood Classification.
2.2.1 Types of Wood.
Forestry Department of Malaysia classified hardwood into three sub-groups
based on the density and durability of natural wood. Based on the classification of wood
Malaysian Grading Rules, (1984) classified the Malaysian timber as below:
Hardwood Weight (group A) has a density of 800kg/rn 3 to 1200kg/rn3 at 15%
moisture content (Tan Boon Tong, 1994). This type of strong wood and do not require
any preservation treatment to be used. The type of wood are Balau Merah, Cengal,
Giam, Belian, Merbau, Tembusu, Resak, Keranji, and Bitis.
7
ii. Medium Hardwood (group B) has a density of 720kg/rn 3 to 880kg/rn3 at 15%
moisture content (Tan Boon Tong, 1994). This type of natural wood less durability
when exposed to weather and soil. Therefore this kind of wood requires preservation
treatment. This is the type of timber Kempas, Kapur, Kasai, Kelat, Keruing, Kulirn,
Merawan, Petaling, Simpoh, Tualang, Mengkuas, Rengas, Resak, Tembusu and Jati.
Light Hardwood (group C) has a density of 400kg/rn 3 to 720kg/rn3 at 5%
moisture content (Tan Boon Tong, 1994). This type of wood do not have natural
durability. This is the type of wood Medang, Mersawa, Nyatoh, Petai, Pulai, Ramin,
rubber wood, Sentang, sesendok, bintangor, durian and kedondong.
iv. Soft wood (group D) has a density less than 400kg/rn 3 . Wood in this category are
dammar minyak, jelutung, Pulai, sempilor and podo.
Otherwise, wood also classified based on the strength of the wood. This new
classification of wood classify into groups A, B, C and D, from wood that has a high
strength to low strength depend on the basis and stress grade wood species. The
strength of timber in Malaysia is divided into the following groups:
i. Group A: Balau, bitis, cengal, Giarn, Keranji, Kempas and tualang with
strength of 4.9 N/mm2 to 9979 N/mm2 (Tan Boon Tong, 1994).
ii. Group B: merbau, balau merah, Resak, Tembusu, kapur, kelat, keruing,
Merawan, rengas and simpoh with strength from 4:34 N/mm 2 to 8.0 N/mm2
(Tan Boon Tong, 1994).
8
iii. Group C: for example durian, kasai, medang, dark red meranti, light red
meranti, mersawa, nyatoh, ramin, rubber and sentang with strength of 2.65
N/mm2 to 6.0 N/mm2 (Tan Boon Tong, 1994).
iv. Group D: damar minyak, jelutong, petal, Pulai and sesenduk. With strength
of less than 2.0 N/mm2.
2.2.2 Main properties of wood
For the purpose of structure and design, the main properties of wood used as a
reference are:
i. Strength
ii. Moisture content
iii. Finishing.
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2.2.3 Safety factor
Strength of wood depends on the factors of density, moisture content, wood
grain structure, defects found in timber and wood modulus of elasticity. Typically wood
has a high strength stronger than the wood has low strength. Although of the same type,
there are also differences in terms of the strength of the wood. Strength variability is
caused by growth factors, age, breed and resources.
Moisture content is the quantity of water content in the wood. Decline in wood
moisture content will cause wood to shrink and may reduce the durability of the wood,
so perfect drying should be done to prevent the wood from deformed or damaged. Wood
used for interior work, it shall be 8% moisture content, while for external work, it must
have a 15% moisture content. Below fiber saturation point, wood strength increased
with decreasing moisture content of wood, while the fiber saturation point was no
change in the strength of the wood.
Wood that had cut usually are not free from defects, this defect may occur from
the growth process, splitting and drying. These defects destroy the look of wood
finishes. Excessive drying, exposure to wind and rain, restructuring and imperfect wood
distance will cause defect and influence of the wood finishing. Figure 2.1 shows the
condition of the wood finish may occur.
There are several factors that should be considered in the design to determine the
safety factor. These factors include the load, size, shape and other factors beyond
engineering research.
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2.3 Wood as material for roof truss structure
The roof is a structure built to protect steep or flat buildings constructed of
wood, steel or concrete. It also acts as a self burden, the burden of roof coverings and
wind load (Jahiman Badrom, 1988). Roof should meet the following requirements and
characteristics
i. Stability
ii. Strength
iii. Durability
iv. Weather resistance
v. Resistance to fire
vi. Thermal insulation properties
vii. design of the building
Truss can be defined as a structural framework composed of members connected
to each other. In principle, it is charged at the points of connection and internal stresses
to its members. This is dependent on the tension compression (Jahiman Badrom, 1988).
The wood used for the trusses should be the least of the group B. There are three basic
types of trusses:
i. Arch truss (Figure 2.2)
ii. Steep truss (Figure 2.3)
iii. Flat truss (Figure 2.4)
(9)
Face knot
e)
Edge knot
11
Surface thk
Erd lit API. (h)
(a) k9s (b) sbake,3, (c) oanes (d) dicks and splits, () bowing (0 croQkIng g) cupping, arili r) twsrirg
Shake
Figure 2.1 Timber finish with defect.
12
14 L FAA ;1 JIL BOWSTRING
GAMBREL
Figure 2.2: Arch Truss
ATTIC
Figure 2.3: Steep Truss
FLAT
Figure 2.4: Flat Truss
FAN
13
The procedure to design the truss as shown below:
i. Select the layout and types of trusses appropriate.
ii. Allocates load on the roof.
iii. Analysis truss to obtain the forces in the members
iv. Moment analysis on the rafter and the bottom hanger ceilings.
V. Member design.
vi. Design connection
vii. Prepare detailed drawings.
2.3.1 Truss connection.
Appropriate connection need for the load of a structure to transfer a member to
another member to be distributed safely and effectively. There are various types of
connections in the market now among them are toothed plate (Figure 2.5), gusset plate
(Figure 2.6), nail (Table 2.1,and Figure 2.7), bolts (Figure 2.8) , screws (figure 2.9),
shear plates, and other patented connection type.