TIME AND COST STUDY ON COLD-FORMED STEEL AND REINFORCED CONCRETE CONSTRUCTION -A COMPARISON

HU WET KJET

A thesis submitted in fulfillment of the requirements for the degree of Master of Engineering

Faculty of Engineering UNIVERSITI MALAYSIA SARAWAK

2008

For my beloved parents.

11

ACKNOWLEDGEMENTS

Hereby, I wish to attribute greatest gratitude to my thesis supervisor, Ms. Ting Sim Nee

and co-supervisor, Associated Professor Dr. Ng Chee Khoon on their guidance and advice

during this research.

I would also like to express my appreciation to those who assisted me in every aspect,

advice, guidance and encouragement to make this thesis a success. I would like to thank

the following companies for their assistance and cooperation.

1. Multi Resources Group of Company

2. EcoSteel Sdn Bhd

3. Sarawak Housing Development Corporation, and

4. All the companies which provided information during interview session

Lastly, I would like to thank everyone who had helped me in completing this master

thesis, for their meaningful information and substantial moral support.

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ABSTRACT

Nowadays, the usage of cold-formed steel is quite common in some developed

countries especially in building construction. However, in Malaysia, cold-formed steel

construction is still considered as a new construction method. In local construction

industry, cold-formed steel is only commonly seen in roof truss construction. In

traditional construction method, reinforced concrete construction is still greatly favoured

by local construction industry.

There are some barriers that limit the usage of cold-formed steel in Malaysia. The

first barrier is market perception that cold-formed steel is a relatively expensive

material. Secondly, the local design engineers and architects have limited knowledge

exposure to cold-formed steel. Thirdly, local market lacks of information about the cold-

formed steel construction in time and cost aspects. So, local market still prefers the

familiar traditional method.

The aim of this research is to study the potential use of cold-formed steel in

Malaysian construction industry as compared with traditional construction method,

reinforced concrete construction. A comparison was done with 2 principles of project

management criteria for a successful project, time and cost. An interview was conducted

with consulting engineers, contractors, developers, material suppliers and architects on

the market reactions towards cold-formed steel.

This research was conducted based on real life reinforced concrete structure

project in Sarawak. Based on the practice of low-cost housing project, the time to

complete the project and the total cost for the project were estimated based on the

experience of site engineers. The design of cold-formed steel framed structure was based

on the dimensions of the reinforced concrete structure. Time and cost estimates were

carried out based on a pilot project in Kuching. Costing and time estimation could be

derived from the sizes of development for both cold-formed steel and reinforced concrete

project.

IV

Comparative analysis showed that the time for cold-formed steel construction was

relatively shorter than the reinforced concrete construction. From cost aspect, the

material cost for the cold-formed steel construction method was slightly more expensive

than the reinforced concrete construction method. However, labour, cost of plant and

machinery for the cold-formed steel construction are cheaper than the reinforced

concrete construction. Generally, the total construction cost of cold-formed steel

construction was still higher than the reinforced concrete construction.

V

ABSTRAK

"Pengunaan Struktur Keluli Gelek Sejuk dalam Industri Pembinaan Tempatan

- Kajian Masa dan Kos"

Pada masa kini, kegunaan dalam pembinaan rangka keluli gelek sejuk adalah

umum di negara-negara maju terutamanya dalam industri pembinaan. Tetapi,

pembinaan ini masih dianggap sebagai cara pembinaan baru di Malaysia. Dalam

industri pembinaan tempatan, keluli gelek sejuk hanya digunakan dalam bidang

pembinaan kekuda bumbung bagi sesebuah bangunan. Cara pembinaan tradisional,

pembinaan konkrit bertulang masih banyak digunakan dalam industri pembinaan

tempatan.

Terdapat beberapa halangan yang menghadkan pengunaan keluli gelek sejuk di

Malaysia. Halangan pertama ialah pasaran tempatan sentiasa menganggap harga keluli

gelek sejuk adalah lebih tinggi. Kedua, jurutera pereka dan arkitek tempatan mempunyai

pengetahuan terhad tentang pembinaan ini. Ketiga, pasaran tempatan tidak ada

maklumat yang mencukupi tentang persembahan pembinaan keluli gelek sejuk dalam

aspek masa dan kos. Jadi, pasaran tempatan masih banyak menggunakan cara

pembinaan tradisional.

Tujuan utama penyelidikan ini ialah membandingkan potensi pengunaan keluli

gelek sejuk dalam industri pembinaan Malaysia dengan cara pembinaan tradisional,

pembinaan konkrit bertulang. 2 aspek projek pengurusan, i. e. masa dan kos telah

dibandingkan. Sebelum perbandingan, tem. uduga dengan jurutera pereka, kontraktor,

pembina tempatan, pembekal bahan mentah dan arkitek telah diadakan untuk

mengetahui reaksi pasaran terhadap keluli gelek sejuk.

Penyelidikan ini dijalankan dengan menggunakan projek sebenar konkrit

bertulang di Sarawak. Dengan project rumah kos rendah ini, masa untuk pembinaan

dan kos untuk projek ini dapat dijangka dengan pengalaman jurutera. Struktur rangka

keluli gelek sejuk direka mengikut dimensi yang sama dengan struktur konkrit

vi

bertulang. Jangkaan masa dan kos projek dibuat berdasarkan projek pertama keluli

gelek sejuk di Sarawak. Selain ini, jangkaan masa dan kos untuk saiz projek yang

berlainan dijalankan. Kos tersebut termasuk kos bahan mentah, kos pemasangan, kos

pekerja, kos penyewaan alat dan mesin dan kos rekaan.

Merujuk kepada keputusan penyelidikan ini, masa pembinaan untuk keluli gelek

sejuk adalah lebih pendek daripada pembinaan konkrit bertulang. Bagi aspek kos, kos

bahan mentah untuk pembinaan keluli gelek sejuk adalah lebih tinggi daripada

pembinaan konkrit bertulang. Tetapi bagi kos pekerja dan kos penyewaan alat dn mesin

untuk pembinaan keluli gelek sejuk adalah lebih rendah daripada pembinaan konkrit

bertulang. Secara keseluruhan, jumlah kos projek bagi pembinaan keluli gelek sejuk

adalah lebih tinggi daripada pembinaan konkrit bertulang.

vii

TABLE OF CONTENTS

CONTENT

TITLE PAGE DEDICATION ACKNOWLEDGEMENT ABSTRACT TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES Chapter 1 INTRODUCTION

1.1 General

1.2 What is Cold-Formed Steel

1.2.1 Common Shapes of Session

1.2.2 Connections

1.2.3 Common Applications

1.2.4 Code/Regulatory

1.2.5 Properties of Cold-Formed Steel

1.2.6 Installation

1.2.7 Fire Protection

1.3 Aim and Objectives

Page

i

11

iii

iv

viii

xii xv

1

2

4

6

7

10

11

11

12

12

viii

Chapter 2 LITERATURE REVIEW 2.1 General 15

2.1.1 Time 17

2.1.2 Cost 18

2.1.3 Quality 19

2.2 Comparison between Cold-Formed Steel and 21

other materials

2.2.1 Cold-Formed Steel and Wood 21

2.2.2 Cold-Formed Steel and Hot-Rolled Steel 29

2.2.3 Cold-Formed Steel and Reinforced 31

Concrete

2.3 Case Study 33

Chapter 3 METHODOLOGY

3.1 General

3.2 Information Sources

3.2.1 Background Information

3.2.2 Interview

3.3 Data Collection and Analysis

3.3.1 Case Study

3.3.2 Cold-Formed Steel Framing Design

3.3.3 Assumptions

3.3.4 Time, Cost, and Quality Analysis

3.3.5 Comparison Analysis

3.3.6 Project Cost Projection

39

39

39

40

41

41

43

43

50

54

55

ix

Chapter 4 RESULTS 4.1 General 56

4.2 Project Description 62

4.3 Results of Cold-Formed Steel Framing 63

Construction

4.3.1 Time 64

4.3.2 Cost 71

4.4 Result for Reinforced Concrete Construction 85

4.4.1 Time 85

4.4.2 Cost 92

4.5 Quality 111

Chapter 5 DISCUSSIONS 5.1 Time

5.2 Cost

5.2.1 Total Construction Cost

5.2.2 Material Cost

5.2.3 Labour Cost

5.2.4 Installation Cost

5.2.5 Plant and Machinery Costs

5.2.6 Design Charges

5.2.7 Other Costs

5.2.8 Cost Projection

5.3 Quality

116

120

120

120

121

123

123

124

124

125

127

X

Chapter 6 CONCLUSIONS 130

REFERENCES

APPENDICES

Appendix A- Questionnaire

Appendix B- Drawings

Appendix C- Cold-Formed Steel Design

Appendix D- Bondek Design

Appendix E- Labour Daily Working Schedule

Appendix F- Plant and Machinery Rental Duration

Appendix G- Grant Chart Format Time Schedule for CFS and RC

(10 houses)

138

143

xi

LIST OF TABLES

Table Page

2.1 Summary of Blower Door Tests 26 2.2 Comparison of Steel and Wood Framing 27 2.3 Light Steel Building versus Reinforced Concrete Building 31 2.4 Cost Comparison between Light Steel Building and Reinforced Concrete 33

Building 3.1 Material Pricing Schedule 45 3.2 Labour Wage Rates Schedule 46 3.3 Machinery Rental Rate Schedule 47 4.1 Construction Time Schedule for Cold-Formed Steel Structure (1 house) 64 4.2 Construction Time Schedule for Cold-Formed Steel Structure (10 houses) 65 4.3 Construction Time Schedule for Cold-Formed Steel Structure (20 houses) 66 4.4 Construction Time Schedule for Cold-Formed Steel Structure (60 houses) 67 4.5 Construction Time Schedule for Cold-Formed Steel Structure (120 houses) 68 4.6 Construction Time Schedule for Cold-Formed Steel Structure (180 houses) 69 4.7 Construction Time Schedule for Cold-Formed Steel Structure (240 houses) 70 4.8 Material Cost Schedule for Cold-Formed Steel Structure (1 house) 71 4.9 Material Cost Schedule for Cold-Formed Steel Structure (10 houses) 72

4.10 Material Cost Schedule for Cold-Formed Steel Structure (20 houses) 73 4.11 Material Cost Schedule for Cold-Formed Steel Structure (60 houses) 74 4.12 Material Cost Schedule for Cold-Formed Steel Structure (120 houses) 75 4.13 Material Cost Schedule for Cold-Formed Steel Structure (180 houses) 76 4.14 Material Cost Schedule for Cold-Formed Steel Structure (240 houses) 77 4.15 Installation Cost Schedule for Cold-Formed Steel Structure (1 house) 78 4.16 Installation Cost Schedule for Cold-Formed Steel Structure (10 houses) 78 4.17 Installation Cost Schedule for Cold-Formed Steel Structure (20 houses) 78 4.18 Installation Cost Schedule for Cold-Formed Steel Structure (60 houses) 79 4.19 Installation Cost Schedule for Cold-Formed Steel Structure (120 houses) 79 4.20 Installation Cost Schedule for Cold-Formed Steel Structure (180 houses) 79 4.21 Installation Cost Schedule for Cold-Formed Steel Structure (240 houses) 79 4.22 Labour Cost Schedule for Cold-Formed Steel Structure (1 house) 79 4.23 Labour Cost Schedule for Cold-Formed Steel Structure (10 houses) 80 4.24 Labour Cost Schedule for Cold-Formed Steel Structure (20 houses) 80 4.25 Labour Cost Schedule for Cold-Formed Steel Structure (60 houses) 80 4.26 Labour Cost Schedule for Cold-Formed Steel Structure (120 houses) 80 4.27 Labour Cost Schedule for Cold-Formed Steel Structure (180 houses) 81 4.28 Labour Cost Schedule for Cold-Formed Steel Structure (240 houses) 81 4.29 Plant and Machinery Cost Schedule for Cold-Formed Steel Structure 81

(1 house) 4.30 Plant and Machinery Cost Schedule for Cold-Formed Steel Structure 82

(10 houses) 4.31 Plant and Machinery Cost Schedule for Cold-Formed Steel Structure 82

(20 houses) 4.32 Plant and Machinery Cost Schedule for Cold-Formed Steel Structure 82

(60 houses) 4.33 Plant and Machinery Cost Schedule for Cold-Formed Steel Structure 83

(120 houses) 4.34 Plant and Machinery Cost Schedule for Cold-Formed Steel Structure 83

(180 houses) 4.35 Plant and Machinery Cost Schedule for Cold-Formed Steel Structure 83

(240 houses) 4.36 Total Construction Cost Schedule for Cold-Formed Steel Structure 84

(1 house) 4.37 Total Construction Cost Schedule for Cold-Formed Steel Structure 84

(10 houses) 4.38 Total Construction Cost Schedule for Cold-Formed Steel Structure 84

(20 houses) 4.39 Total Construction Cost Schedule for Cold-Formed Steel Structure 84

xii

(60 houses) 4.40 Total Construction Cost Schedule for Cold-Formed Steel Structure 84

(120 houses) 4.41 Total Construction Cost Schedule for Cold-Formed Steel Structure 85

(180 houses) 4.42 Total Construction Cost Schedule for Cold-Formed Steel Structure 85

(240 houses) 4.43 Construction Time Schedule for Reinforced Concrete Structure (1 house) 85 4.44 Construction Time Schedule for Reinforced Concrete Structure (10 houses) 86 4.45 Construction Time Schedule for Reinforced Concrete Structure (20 houses) 87 4.46 Construction Time Schedule for Reinforced Concrete Structure (60 houses) 88 4.47 Construction Time Schedule for Reinforced Concrete Structure (120 houses) 89 4.48 Construction Time Schedule for Reinforced Concrete Structure (180 houses) 90 4.49 Construction Time Schedule for Reinforced Concrete Structure (240 houses) 91 4.50 Material Cost Schedule for Reinforced Concrete Structure (1 house) 92 4.51 Material Cost Schedule for Reinforced Concrete Structure (10 houses) 94 4.52 Material Cost Schedule for Reinforced Concrete Structure (20 houses) 96 4.53 Material Cost Schedule for Reinforced Concrete Structure (60 houses) 97 4.54 Material Cost Schedule for Reinforced Concrete Structure (120 houses) 99 4.55 Material Cost Schedule for Reinforced Concrete Structure (180 houses) 101 4.56 Material Cost Schedule for Reinforced Concrete Structure (240 houses) 102 4.57 Installation Cost Schedule for Reinforced Concrete Structure 104 4.58 Labour Cost Schedule for Reinforced Concrete Structure (1 house) 104 4.59 Labour Cost Schedule for Reinforced Concrete Structure (10 houses) 105 4.60 Labour Cost Schedule for Reinforced Concrete Structure (20 houses) 105 4.61 Labour Cost Schedule for Reinforced Concrete Structure (60 houses) 105 4.62 Labour Cost Schedule for Reinforced Concrete Structure (120 houses) 106 4.63 Labour Cost Schedule for Reinforced Concrete Structure (180 houses) 106 4.64 Labour Cost Schedule for Reinforced Concrete Structure (240 houses) 106 4.65 Plant and Machinery Cost Schedule for Reinforced Concrete Structure 107

(1 house) 4.66 Plant and Machinery Cost Schedule for Reinforced Concrete Structure 107

(10 houses) 4.67 Plant and Machinery Cost Schedule for Reinforced Concrete Structure 108

(20 houses) 4.68 Plant and Machinery Cost Schedule for Reinforced Concrete Structure 108

(60 houses) 4.69 Plant and Machinery Cost Schedule for Reinforced Concrete Structure 108

(120 houses) 4.70 Plant and Machinery Cost Schedule for Reinforced Concrete Structure 109

(180 houses) 4.71 Plant and Machinery Cost Schedule for Reinforced Concrete Structure 109

(240 houses) 4.72 Total Construction Cost Schedule for Reinforced Concrete Structure 109

(1 house) 4.73 Total Construction Cost Schedule for Reinforced Concrete Structure 110

(10 houses) 4.74 Total Construction Cost Schedule for Reinforced Concrete Structure 110

(20 houses) 4.75 Total Construction Cost Schedule for Reinforced Concrete Structure 110

(60 houses) 4.76 Total Construction Cost Schedule for Reinforced Concrete Structure 110

(120 houses) 4.77 Total Construction Cost Schedule for Reinforced Concrete Structure 111

(180 houses) 4.78 Total Construction Cost Schedule for Reinforced Concrete Structure 111

(240 houses) 5.1 Total Construction Time for Cold-Formed Steel Structure and 116

Reinforced Concrete Structure 5.2 Construction End Date for Cold-Formed Steel Structure and Reinforced 116

Concrete Structure 5.3 Total Construction Cost for Cold-Formed Steel Structure and Reinforced 120

xiii

Concrete Structure 5.4 Total Construction Cost per Unit for Cold-Formed Steel Structure and 120

Reinforced Concrete Structure 5.5 Material Cost for Cold-Formed Steel Structure and Reinforced Concrete 121

Structure 5.6 Labour Cost for Cold-Formed Steel Structure and Reinforced Concrete 122

Structure 5.7 Installation Cost for Cold-Formed Steel Structure and Reinforced 123

Concrete Structure 5.8 Plant and Machinery Cost for Cold-Formed Steel Structure and 123

Reinforced Concrete Structure 5.9 Comparison of CFS and RC on Percentage for the Cost 126 6.1 Earlier Completion Time for Cold-formed Steel Construction Compared 130

With Reinforced Concrete Construction 6.2 Total Construction Cost for Cold-Formed Steel Structure and Reinforced 132

Concrete Structure 6.3 Percentage of Material Cost for Cold-Formed Steel Structure and Reinforced 132

Concrete Structure

xiv

LIST OF FIGURES

Figure Page

1.1 Roll Forming Machine 3 1.2 Cold-Roll Forming 4 1.3 Basic Shapes of Cold-Formed Steel 5 1.4 Common Shapes of Cold-Formed Steel Sections 5 1.5 Cold-Formed Sections Used in Structural Framing 6 1.6 Decks, Panels and Corrugated Sheets 6 1.7 Wall framing 7 1.8 Whole House Framing 7 1.9 Storage Racking 10 2.1 U. S. Houses Using Steel Framing by Application 1997-1999 16 2.2 Low Cost Housing in Australia using Colorbond® Steel for Roofing 34

and Walling 2.3 The Coddington House at Bayview features LYSAGHT MINI ORB® 35

Wall Cladding in COLORBOND® Steel 2.4 Wall Cladding in COLORBOND® Steel 35 2.5 Wall Cladding in COLORBOND® Steel 35 2.6 Home in Corio Bay Geelong Victoria 36 2.7 Lightweight Steel Framed House 37 2.8 Lightweight Steel Framed House 37 4.1 The Usage of Cold-Formed Steel in the Local Building Industry 56 4.2 Cold-Formed Steel Roofing 57 4.3 Important Criteria that Industry Considered 59 4.4 Suitability of Cold-Formed Steel in Malaysian Construction Industry 60 5.1 Total Construction Time for CFS and RC Construction in Different 117

Scale 5.2 Construction Cost Difference per Unit of House 125

xv

CHAPTER 1

INTRODUCTION

1.1 GENERAL

The construction industry has entered a new era and one should look forward for more

advanced structures. The material of construction is one of the important aspects that

one should consider in order to fulfill the quality, utility, economy and beauty of

construction. Steel, a modern human creation, is a basic ingredient in construction along

the way in the evolution chain. As early as the fourth century B. C, iron has been

discovered in China.

The use of cold-formed steel in construction has been quite common in some

countries such as United States of America, Australia and Japan. According to Yu (1997),

cold-formed steel members were widely used in building and bridge construction, storage

racks, highway products, drainage facilities, grain bins, transmission towers and various

types of equipment. According to PATH (2002), steel framing had been used in interior

non-load bearing and curtain walls in commercial buildings for many years. However,

cold-formed steel only attracts the attention for use in load bearing wall, floor and roof

framing in residential construction recently. More and more architects and engineers

prefer to design the structures with cold-formed steel as the main materials. It is

because cold formed steel could provide a relatively more stable framework for a

structure.

According to Wagner (2003), Melbourne's Colonial Stadium in Australia is one of

a great steel structure. The most challenging feature for this well-built stadium in

engineering perspective is the roof. The main arch of the roof span is nearly 300 m. The

design of the long span roof structure was made of extensive use of cold formed tabular

members which had undergone thorough experimental testings and research. The main

I

arch of the roof has a structural steel weight of only 85 kg/m2. This represents an

extremely efficient use of cold-formed steel for such a span.

Currently, steel framing is more commonly used in geographical locations that

experience frequent weather related damage or natural disasters such as hurricanes and

earthquakes. Steel framed homes are commonly found in Hawaii. Steel is used in such

locations because it has higher tensile and greater bending strength than lumber. Thus

it can resist the destructive forces exerted upon residential structures during such

natural disasters. According to Yu (1997), as compared to other materials such as timber

and concrete, cold-formed steel members offer the following advantages in terms of

lightness, strength, stiffness, ease of prefabrication and mass production, fast and easy

erection and installation, and economy in transportation and handling.

Besides the availability of cold-formed steel framing, there are still other barriers

that limit its usage in construction. The primary barrier is the cost. The construction

industry would use the new building method only if they manage to exhibit clear cost

and quality advantages. The second barrier is how the thermal conductivity of cold-

formed steel affects energy use in homes. In Malaysia, use of cold-formed steel is still at

the very beginning stage. One can hardly see many cold-formed steel framed buildings

around. Usually, cold-formed steel truss is the most common element that is used in

construction here.

1.2 What is Cold-Formed Steel ?

For building constructions, there are two main types of structural steels: hot-rolled steel

and cold-formed steel. According to Sunway Homes Steel Structures (2005), hot-rolled

steel shapes are formed at an elevated temperature. For cold-formed steel, the shapes

are formed at room temperature. The cold-formed steel is generally shaped from steel

plate, sheet and strip material. According to Chen (NA), the manufacturing process

involves forming the material by either press-braking or cold roll forming to achieve the

2

desired shape. Examples of the cold-formed steel are corrugated steel roof and floor

decks, steel wall panels, storage racks and steel wall studs.

Press-braking method is often used to produce small quantity of simple shapes.

Cold rolling-forming method is the most widely used method in producing roof, floor and

wall panels. It is also used for production of structural components such as Cees, Zees,

and hat sections. Sections can usually be made from sheets up to 60 inches (1.5 m) wide

and from coils more than 3,000 feet (1,000 m) long.

During cold rolled forming, sheet stock is fed longitudinally through a series of

rolls, each of which works the sheet progressively until it reaches the desired shape. A

simple section may require as few as six pairs of roll, but a complex shape can require as

many as 24 to 30. The thickness of material formed can generally range from 0.004 (0.10

mm) to 0.312 inches (0.79 mm). Heavy duty cold forming mills can handle steel up to 3/4

of an inch (19mm) thick.

Figure 1.1: Roll Forming Machine

3

Figure 1.2: Cold-Roll Forming

(Source: Chen, NA. An Overview of Cold-Formed Steel Structures)

Cold-formed steel is an ideal structural material in many aspects, which exhibits

a number of useful structural characteristics. It is a strong and reliable material that

can be produced to meet specifications and it can be fabricated precisely. It carries both

tension and compression loads. The yield strength of tension member is approximately

equal to the crushing strength of compression member. Its deformation is directly

proportioned to applied loads, and is fully recovered on removal of the loading. It will

also remain stable under long-term loading at normal temperature.

1.2.1 Common shapes of sections

According to Corus (2003), cold-formed steel sections are used in many industries and

are specially shaped to suit the particular application. In building purpose, the most

common sections are the C and the Z shapes. There are a whole range of variety of these

basic shapes, including those with edge lips, internal stiffeners and bends in the webs.

Other section shapes are the "top-hat" section and the modified I section. The

sections can also be joined together to form compound members. The additional lips and

stiffeners are included because unstiffened wide thin plates are not able to resist

significant compression and consequently the use of steel in the section becomes

inefficient. However, a highly stiffened section is not easy to form and is often not

4

practicable from the point of view of its connections. Therefore, a compromise between

section efficiency and practicability is often necessary.

Figure 1.3: Basic Shapes of Cold-Formed Steel (Source: NAHB, NA. Designing Homes Using Cold-Formed Steel)

Figure 1.4: Common Shapes of Cold-Formed Steel Sections (Source: Chen, NA. An Overview of Cold-Formed Steel Structures)

5

CEýZ ILL IL

JF. (a) (b) tcf tdt iel (fY (ý4 (h}

J-1

L -V

(i) (j)

I toi lp)

t"" w"`"'1

L... JA. _J 4 k)

(q) (r)

I (I) (g)

ffi

vL tmi

(t)

Inur- 1

(n)

Figure 1.5: Cold-Formed Sections Used in Structural Framing

(c) (a) (b) Roof decks

(d) {e} tfý Lo1, g- span roof decks

LJUJ TL i. l U LJ 1J (g} (h) (i) (1)

Floor and roof panels

(1G) (1) (m)

Curtain wall panels Ribbed panels Corrugated sheets

Figure 1.6: Decks, Panels and Corrugated Sheets

1.2.2 Connections

According to Yu (1997), welds, bolts, screws, rivets, and other special devices such as

metal stitching and adhesives are generally used for cold-formed steel connections. The

AISI Specification contains only the design provisions for welded connections, bolted

connections, and screw connections.

6

1.2.3 Common Applications

According to Corus Construction Centre (2003) and Chen (NA), the structural usage of

cold-formed sections that utilize these features are as follows:

(a) Roof and Wall Members

Traditionally, predominant use of cold-formed steel has been as purlins and side

rails to support the cladding in industrial type buildings. These are generally based on

the Z section (and its variants), which facilitates incorporation of sleeves and overlaps to

improve the efficiency of the members in multi-span applications. Special shapes are

made for eaves members and so on.

Figure 1.7: Wall Framing

Figure 1.8: Whole House Framing

(Source: AISI, NA. Cold-Formed Steel Design Gallery)

7

(b) Steel Framing

An increasing market for cold-formed steel sections is the site-assembled frames

and panels for walls and roofs, and stand-alone buildings. This approach has been used

in light industrial and commercial buildings and in mezzanine floors of existing

buildings. According to Gaylord (1990), cold-formed steel is also used in residential steel

framing system to replace the use of lumber in the individual beams, joists, studs,

column framing members and other structural components.

(c) Wall Partitions

A special application for very light sections is used in conjunction with plaster

board panels in stud wall partitioning to form a thin robust wall.

(d) Large Panels for Housing

Storey-high panels can be factory-built and assembled into housing units on site.

This is an extension of the approach used for timber framing.

(e) Lintels

A significant market for specially formed cold-formed sections is as lintels over

doors and windows in low rise masonry walls. These products are often powder coated

for extra corrosion protection.

(f) Floor Joist

Cold-formed sections may be used as an alternative for timber joists in floors of

modest span in domestic and small commercial buildings.

(g) Modular Frames for Commercial Buildings

A prefabricated modular framing and panel system using cold-formed channels

and lattice joists had been developed for use in buildings up to 4-storied height. Although

8

primarily developed for commercial building, this modular system has broad application

in the areas as educational and apartment buildings.

(h) Trusses

(i) Space Frames

(j) Curtain Walling

A modern application in cladding framing to multi-storied mullions and transoms

in standard glazing systems, steel buildings, and as mullions and transoms in standard

glazing systems.

(k) Prefabricated Buildings

The transportable prefabricated building unit (such as the ubiquitous site hut) is

a common application use of cold-formed steel. Other applications are used as

prefabricated "toilet pod" units in multi-storied buildings.

(1) Frameless Steel Buildings

Steel folded plates, barrel vaults and truncated pyramid roofs are examples of

systems that have been developed as so-called frameless buildings (i. e. those without

beams and which rely partly on a "stressed skin" action).

(m) Storage Racking

Storage racking systems used in warehouses and industrial buildings are made

from cold-formed steel sections, mostly consist of special clip attachments, or bolted

joints for easy assembly.

9