Introduction to Steel Design

INTRODUCTION TO STEEL DESIGN

STRUCTURAL STEELWORK & TIMBER DESIGN

ECS328

INTRODUCTION TO STEEL DESIGN

MOHD AZUAN TUKIAR

BKBA 2.12

[email protected]

Faculty of Civil Engineering, UiTM Penang

STEEL DESIGN

1. INTRODUCTION TO STEEL DESIGN

5. DESIGN OF STEEL CONNECTION USING

SIMPLE CONNECTION

2. DESIGN OF RESTRAINED

BEAM

3. DESIGN OF AXIALLY

LOADED STEEL

COLUMN

4. DESIGN OF AXIALLY LOADED

TENSION

MEMBERS

1. Know properties and

composition

type of steel.

(CO1-PO3)

2. Know types of structural steel

elements, steel section elements, steel section

and application of

steelwork . (CO1-PO3)3. Know the theory used in structural

steel design and

different design

methods for building using structural

steelwork. (CO1-PO3)

Steel and aluminum are the twomain structural materials used in

Civil Engineering works. This course

will focus mainly on steel structures

although the principles involvedare similar in both materials

The origin of modern buildingmaterial such as structural

steelwork can be traced back to

the birth of Industrial Revolution in

the later part of the 18th Centurythe later part of the 18th Centuryand it marked the end of era in

which timber and masonry were

the dominant materials ofbuilding.

The design of modern steelwork is undertaken in U.K to comply with the requirement of BS5950: Part 1: 2000. Currently, Malaysia also has applied

BS5950: Part 1: 2000 in design of steelwork in building and later, it replaced

with EUROCODE 3 – EN1993: Design of Steel Structure.

PROPERTIES OF

STEEL

1. PHYSICAL

2. CHEMICAL

3.MECHANICAL

1. The measurement of a

physical property may

change the arrangement of

matter in a sample, but notthe structure of its molecules.

2. In other words, a physical

property may involve a

physical change, but not a

chemical change

3. Examples of physical

1. Mechanical properties of steel

are defined as the reaction of

the material to certain types

of external forces.

2. Examples of mechanical

properties include Tensile

strength, Yield Strength,

Ductility, Hardness, Notch

Toughness, Fatigue

1. Properties that used to characterize materials in reactions

that change their identity3. Examples of physical

properties include mass,

density, color, boiling point,

temperature, volume, density,specific heat, thermal

expansion, conductivity,

melting point etc.

4. Physical properties of steel

was depend on the chemical

properties of steel

2. The basic element is iron and Carbon. The other alloyingelements will create special properties in the steel.

3. The carbon content must be kept low, preferably at 0.25% or

less (BS EN 10024, BSEN 10025). Steel with high carbon

content will suffer from problems such as low ductility (too

brittle) as well as welding difficulties and not suitable forstructural steel members.

4. Carbon (C) Ferrous (Fe) plus P, S, Mg, Vn, Cr, Mo, Ni, Cu andetc

5. Composition of steel that differentiate the physical and

mechanical properties of the steel

1. Aluminum & Alloys

FERROUSNON-

FERROUS

CAST -IRON

STEEL

METAL

CLASSIFICATION & COMPOSITION OF STEEL

1. Aluminum & Alloys

2. Cooper & Alloys

3. Magnesium & Alloys

4. Nickel & Alloys

5. Zinc & Alloys

6. Titanium

1. Grey Cast Iron2. White Cast Iron

3. Malleable Cast

Iron

4. Ductile Cast iron

1. Plain Carbon Steel2. Alloy Steel

3. Stainless Steel

4. Tool Steel

STEEL STRUCTURAL

TIES

SHEETING RAILS

BEAM & GIRDERSBRACING

STRUCTURAL

ELEMENTS

STRUT

TRUSSES

PURLINS

COLUMN & STANCHIONS

HOT ROLLED SECTIONS

COMPOUND SECTIONS

STEEL SECTIONS

BUILD-UP SECTIONS

COLD ROLLED SECTIONS

STEEL SECTIONS

ADVANTAGES OF STEEL

STRENGTH

UNIFORMITY

FLEXIBILITY

ELASTICITY

DUCTILITY

SUSTAINABILITY

REDUCE OVERALL COST

APPLICATION OF

STEELWORK

BUILDING FRAMES

BRIDGES CHIMNEY

CONTAINERSMASTTEMPORARY SUPPORT

WHY DO WE NEED DESIGN ??

FULLFILL INTENDED FUNCTION

SAFETY ASPECT – AVOID UNDERDESIGN

ECONOMIC ASPECT – AVOID OVERDESIGN

STEEL DESIGN

THEORY

PLASTIC DESIGNELASTIC DESIGN

LIMIT STATE DESIGN

In elastic design, the maximum

load that a structure couldsupport was assumed to equal

the load that first caused a stress

somewhere in the structure to

equal the yield stress of the

materialSteel is almost perfectly elastic

up to the yield point & structures

are analyzed by elastic theory.

Sections are sized with yield

stress not exceededOne drawback of using elastic

method for designing such

Plastic design takes

advantage of an important &

unique property of mild steel,

namely its ductility.

Plastic design take into

account behavior past theyield point & it is based on

finding the load that causes

the structure to collapse.

Plastic design take into

consideration long yield

Structure should be design by

considering the limit states beyondwhich they would become unfit for

their intended uses.

Appropriate partial factor should beapplied to provide adequate

method for designing such

structures with ductile membersis that the reserve strength

beyond elastic limit is neitherquantified nor utilized explicitly.

But more importantly, the yield

state (mechanism) of thestructure at ultimate strength

level is also not known. The yield

mechanism may involve

structural members that could

lead to undesirable system

performance under accidentaloverloading or extreme events,

such as strong earthquake

ground motion, blast, impact,

etc.

consideration long yield

plateau which allows thepossibility of considerable

plastic strain at constant stress

WORK LOAD = COLLAPSE LOAD

LOAD FACTOR

In reality, structure can fail not

only due to failure of material,

but also due to excessive

deformation.

Therefore, Limit State Design

concept was introduced

applied to provide adequate

degrees of reliability for :

ULTIMATE LIMIT STATE - Strength,

Stability (overturn & sway), fracture(fatigue & brittle)

SERVICEABILITY LIMIT STATE -

Deflection, Vibration, Repairable

damage due to fatigue, Corrosion& Durability .

When ULS are reached, whole

structure or part of it collapses while

when SLS reached, the whole

structure or part of it is unfit for

normal use but do not indicatecollapse mechanism.

DESIGN METHOD

Simple DesignContinuous Design

Semi-Continuous Design

Pinned joint, transmit

nominal moment. Joint

only developed a nominal moment.

Columns and

connections must be

designed for this moment.

Rigid joint, transmit full

moment.

Joint has some

sufficient rotational

stiffness to transmit

moment from one

member to another. Joint must sufficient

capacity to resist the

Semi-rigid joint,

transmit partial

moment. Joints has moment.

Assumed pinned

connections for the

analysis purposes.

Must provide lateral

force resisting system

(braces, shear wall,

etc).

Simple and

economical. Use

whenever possible.

capacity to resist the

moment and other

forces developed from the analysis based on

the assumed rigid

connection.

Rigid connection is the

default in most

computer software

moment. Joints has some degree of

rigidity, also called

semi-rigid

connection.

Performance of joint

must be based on

experimental

evidence

Semi-Continuous Design

Continuous Design

Simple Design

INTRODUCTION TO EUROCODE

INTRODUCTION TO EUROCODE