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School of Architecture, Building and Design

Bachelor of Quantity Surveying (Honours)

Construction Technology 3[QSB 2514/BLD 60304]

Group Assignment

Name : Tan Shen Sin 0324602

Thasia 0329051

Wong Sher Sheng 0329950

Topic : Steel Framing System

[ Cold-Form Structures + Composite Floor Slab ]

Lecturer : Mr Chai Voon Chiet

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Table of content Pages

Introduction of Steel framing system 3

Cold form structures

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Composite floor slab 8

Installation of composite slab 9

Advantages & disadvantages of cold form structures 10-11

Advantages & disadvantages of composite slab 12-13

Case study 14-18

Reference 19

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Steel framing system

Introduction

Steel was first produced in the Middle Ages, but it was only used for building structural

purposes until just over a century ago. Today many remarkable structures demonstrate the

possibilities of using this material in their appearances. Among which include the Eiffel Tower.

The strength-to-volume ratio, the wide range of possible applications, the reliability of the

material and the ability to give shape to nearly all architectural wishes are the reasons to choose

this material for the main structure of a building.

For the structural framing purposes, the steel sections are normally used for beams,

columns and roof truss constructions. In Malaysia, these steel sections are manufactured to

specific British Standards. These sections could be either hot-rolled or welded. Universal Beam

(UB) is a common section used for structural beam, while Universal Column (UC) is a common

section for structural column. The main difference between the UB and UC is the depth (D) to

width (B) ratio of the section.

Houses that adopted Steel Framing System

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Cold form structure

Cold-formed steel framing is made from strips of structural quality sheet steel that are fed

through roll forming machines with a series of dies that progressively shape the steel into C-

shaped sections, or formed into a variety of other shapes, including “U”, “Z”, and even hat-

shaped sections. Cold-formed steel framing members can be formed from a wide range of

material thickness that enables them to meet the requirements of nearly all structural and non-

structural applications.

Manufacturing process

1. Cold-formed steel starts with the production of raw steel, which is made by combining

iron ore or steel scrap with small amounts of carbon in a Basic Oxygen Furnace (BOF) or

Electric Arc Furnace (EAF)

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2. Molten steel is poured into slabs that are reduced into thinner strips of steel, called “hot

band.” Increasingly, steel mills are employing a new, very efficient process called direct

reduction to make “hot band.”

3. In the steel finishing process, the hot band is reduced once again into “cold rolled

steel.” A protective coating of zinc is then added through the galvanization process. The

final product is called a “coil.”

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4. To convert coils into cold-formed steel framing members, they are first slit into widths

that match the intended dimensions of the final product.

5. The slit coils of cold-formed steel are formed into C-sections and other shapes usually by

roll forming the steel through a series of dies. Penetrations for plumbing and electrical

runs are also punched at pre-determined locations, helping reduce installation times. No

heat is required to form the shapes and thus the name cold-formed steel.

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6. The cold-formed steel framing materials are then either used to build wall and floor

panels, and roof trusses, or delivered to the job site in bundles.

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Composite floor slab

Composite slabs comprise reinforced concrete cast on top of profiled steel decking. This acts as

formwork during construction and external reinforcement at the final stage. The decking can be

either re-entrant or trapezoidal. Trapezoidal decking may be over 200 mm deep which known as

deep decking. Additional reinforcing bars may be placed in the decking troughs, particularly for

deep decking. They are sometimes required in shallow decking when heavy loads are combined

with high periods of fire resistance.

Trapezoidal decking Re-entrant decking

Re-entrant or trapezoidal decking of 50 to 60 mm depth can span around 3 m unpropped, 80 mm

deep trapezoidal profiles can span up to around 4.5 m unpropped, and deep decking can achieve

around 6 m. Overall slab depths range from 130 mm upwards.

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Installation of Composite Slab

1. Installation of decking

First, the contractor will place metal decking on the structural steel at predetermined

points in the erection sequences. Powder actuated tools can be used as an alternative of

welding to attach metal decking to the structural steel. A nail-like fastener is driven

through the metal deck into the steel beam.

2. Shear connectors

Installing shear connector to create a strong bond between the steel beam and the

concrete floor slab which is poured on top of the metal decking. The tip of the shear

connector may be placed in a ceramic ferrule to retain the weld during the welding

process.

The ferrules are removed before the concrete is poured.

3. Installation of concrete

Lastly, after the decking has been installed, concrete contractor will cast the concrete,

usually by pumping method on top of the composite metal decking, shear connectors, and

welded wire fabric or rebar grid.

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Advantages of cold form structures

Strength

Steel has the highest strength to weight ratio of any building material. The strength of

cold-formed steel provides architects with greater flexibility.

Durable

Steel can last hundreds of years without any deterioration due to the fact that steel is

inorganic, and thus impervious to termites and rot. A protective layer is used to provide

high resistance to corrosion.

Non-combustible

Steel will not contribute to the spread of a fire. Because of this, cold-formed steel projects

can easily be designed to meet code fire rating requirements. This gives lower costs and

broader coverage for many types of construction insurance.

Sustainable

Steel is the only building material that is infinitely recyclable. As a recognized green

building material, cold-formed steel framing projects can earn credits for green building

ratings such as LEED.

Cost-effective

By helping to minimize the risk, the use of cold-formed steel results in lower insurance

costs for builders and owners. The cold-formed steel construction methods allowing

builders to complete the projects months faster than with other framing materials due to

shorter construction cycles,

Lightweight

Cold-formed steel are usually lightweight, making it easy to transport and erect

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Disadvantages of cold-form structure

Low fire resistance

Even though light gauge steel won’t burn, it can still lose strength in a fire.

Unit price

Cold rolling process is expensive compare to hot-rolled system due to the equipment and

labour cost in production.

Careful requirement

Careful treatment is required when assembling as it can caused buckling as cold-formed

steel is not as strong in physical structure compare to hot-rolled steel.

Difficult connecting

Due to the thinness of cold-form steel, connecting steel section must be done in caution,

especially for welded joints.

Thermal and sound insulation

It has low thermal and sound insulation. Steel also transmit sound more readily than

wood therefore installing internal soundproofing may be required.

Rusting

Steel is subject to rusting due to moisture or water.

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Advantages of composite slab

Versatility

Composite slab can be adapted to many practical cases and a multitude of solutions.

Resistance weight ratio

Have a great resistance with less weight, thus enabling a global reduction of the

structure’s weight. The minimum slab edge measures is only 12 cm.

Quick installation

The time taken for installation is shorter than timber flooring. The absence of props

means that more than one floor can be concreted at the same time, thus reducing

construction time per floor.

Cost reduction

Cost reduction in both in terms of labour costs and material cost as there is no need for

props, and less concrete is used.

Safe

The concrete slab is being poured progress is not hindered in other areas e.g. the floors

above.

Strength

Steel decking provides flexible reinforcement, combined with the comprehensive strength

of the concrete, for an all-round stronger slab.

Easy on site handling

Steel decking is transported to site in pre-cut lengths, and in pre-packaged bundles.

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Disadvantages of composite slab

Brittle

Composite is more brittle than wrought metal thus it is easily damaged.

Crack

The biggest problem for composite slab is cracking.

Temperature sensitive

Can cause expands and contracts with temperature change

Might cause overloading

During placement on concrete, care should be taken to avoid overloading the decking or

supporting structural member.

Replacement

Damaged or faded material must be replaced, and it is a soft material that wears easily.

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CASE STUDY

Embassy Suites ,Columbus, OH

Background

Building: Embassy Suites

Location: Columbus Ohio

Size: 135000 square foot

Capacity: 224 guest rooms, 7 storey

Completion: 2009

Design team

Project architect: Bird Houk Collaboration

Project Engineer: Jezerinca Geers

General contractor: Brackett Builder

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CFS Use at Embassy Suites

Cold form steel(CFS) framing was used for interior and exterior load-bearing and non load-

bearing walls, and floor and roof joists. A very small amount of structural steel was used within

the top six floors of the cold-form steel portion of the structure. The podium level was

constructed of a 3 1/2” concrete over 3” deep composite metal deck on top of structural steel. In

order to provide the fire-resistance necessary in a residential building of this type, the floors and

flat roof are constructed with the Trade-Ready joist system supporting metal deck. The Trade-

Ready system is a proprietary system that allows for ease of utility installation through pre-

fabricated holes in the joists.

Cost Vs Competition

The general contractor initially estimated the cost of hotel buildings of this type to evaluate the

differences between steel and concrete. They determined that steel beats the competition by a

wide margin. The contractor estimates that the cost savings of CFS compared to concrete is at

least $10/SF of floor area. For the Embassy Suites, this would equate to approximately

$1,350,000 for the 135,000 square foot of floor area framed with CFS.

Construction Cycle Time

For hotel owners, timing is extremely important. The time from groundbreaking to finish was 13

months. The CFS framing was complete in 96 days. According to Hoying, “ the panelised

Worthington Integrated Building Systemschedule is very dependable and predictable. Panelized

steel systems obviously do not experience weather delays during cold weather was you would

see with concrete, block, and precast planks.” Because there is no concrete shoring to get in the

way, mechanical and electrical trades can get started quicker with their rough-in work.

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Case Study II

Background

Building: Poly Canyon Village Student Housing

Location: San Luis Obispo, California

Size: 1,400,000 square foot

Year completed: 2009

Contract value: $250,000,000

Certification: LEED Gold

Design team

Client: California Polytechnic State University

Architect: Niles Bolton Associates

CFS Use At Poly Canyon Village

CFS for this project was used for the wall framing exclusively relying on four-inch studs ranging

from 33 to 78 mil thickness. The thicker 68 mil studs were used at the ground floor and the stud

thickness decreased as additional floors were added. Floor framing was accomplished with

Dietrich TradeReady CFS floor joins with 9/16-inch shallow metal decking, and USG Levelrock

was poured one inch over the top of the decking for the subfloor. Roof framing consisted of steel

trusses fabricated by Pacific Coast Truss Fabricator, a CEMCO Company. Fire-treated structural

plywood was used on the roof.

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Tegan Sullivan of Clark Design/Build, who has served as the captain for the team, confirmed the

LEED certification requirement is one of the main reasons steel framing was selected. Cold-

formed steel and the panaelization process was attractive because of the off-site plant. In addition

to qualifying for LEED credit because of steel’s recycled content, the project also earned LEED

points because the manufacturing plant was located within 500 miles of the job site. The project

achieved a LEED Gold Certification from the U.S. Green Building Council.

Construction Cycle Time ( Schedule )

The construction was completed in six months less time using CFS framing compared to the

schedule for a concrete structural frame. The entire project could have been turned over a year

early but the lead time for some of the logistics like furnishings, retail build-out and training of

facility managers was not enough to advertise and lease the rooms.

The flexibility to pre-fabricate panels off-site definitely contributed to the project’s success, and

the speed at which the steel framing installer, KHS&S of California, was able to install the

structures on site allowed for all the subcontractors to be productive. The efficiencies gained

through pre-fabrication made it possible to start several components in several places at the same

time, which significantly cut down on any potential downtime for workers and subcontractors.”

The use of new techniques using steel helps reduce costs of the overall project and makes project

like Poly Canyon Village more marketable since steel is a stable, engineered material with

consistent properties. On completion inmate 2009, Poly Canyon Village is an impressive

apartment development for Cal Poly students with amenities including a swimming pool,

community center and a central retail plaza.

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Reference:

Emma Goodgion(2016). How Cold-Formed Steel is Made. Retrieved from 1 December 2017

from https://sfia.memberclicks.net/how-cold-formed-steel- is-made

Composite construction. Retrieved from 1 December 1, 2017 from

https://www.steelconstruction.info/Composite_construction

Composite construction. Retrieved from 1 December 2017 from

http://www.enme.umd.edu/~ccfu/ref/CompConstCamber1_Fu.pdf

Advantages of Composite Slabs. Retrieved from 1 December 2017 from

https://www.incoperfil.com/advantages-cms-1-51-189/

Metal deck(2017).The Advantages of Steel Decking. Retrieved from 1 December 2017 from

https://www.raisedfloor.co.uk/the-advantages-of-steel-decking/

Bill Hutchison(2007).Advantages-and-6-disadvantages-of-composite-decking. Retrieved from 1

December 2017 from http://www.renovateaustralia.com/2007/03/03/6-advantages-and-6-

disadvantages-of-composite-decking/

Emma Goodgion(2016). Advantages of Cold-Formed Steel Framing. Retrieved from 1

December 2017 from http://www.cfsteel.org/advantages-of-cold-formed-steel- framing

Prof. S.R.Satish Kumar and Prof. A.R.Santha Kumar(2015). Design of Steel Structures.

Retrieved from 1 December 2017 from

http://nptel.ac.in/courses/105106113/5_cold_form_steel/2_advantages.pdf

Steel framing alliance(2016). The Embassy suites is a seven story hotel built by Brackett Builder

of Troy, Ohio. Retrieved from 1 December 2017 from

http://www.steelframing.org/PDF/cycletime/EmbassySuites.PDF

Steel framing alliance(2016). Park 4200 is a six story apartment project built over a three story

parking garage. Retrieved from 1 December 2017 from

http://www.steelframing.org/PDF/cycletime/PolyCanyonVillage-FINAL-1.pdf