Basic principles of steel structures. Dr. Xianzhong ZHAO

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Basic principles of steel structures

Dr. Xianzhong ZHAO

Lecture Questionnaire (1)

Language preferred ( C = in Chinese, E = in English)

E C E C 6 other E C C C 7 E E C C 5 E C E E 4 E E E C 3 E E E C & E 2 E E E E 1

Tick the one you prefer Coursework & written exam Handout & textbook Writing on the blackboard Oral Presentation NO.

From this course you prefer to:

Learn steel struc. 1 2 3 4 5 6 7 Practise in English format English

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Syllabus

— Aims

To introduce procedures for designing steel members and connections. — Syllabus (total 41 courses)

; Introduction =>2

; Steel properties =>6

; Tension members =>3

; Compression members (Columns) =>7

; Bending Members (Beams) =>8

; Beam-columns =>7

;Connections =>8

— Coursework & Assessment

; Assignment 1 Attendance, activities & Coursework 30%

; Assignment 2 Experiments EPUT 10%

Introduction

Outlines

—

what is steel structure?

—

why choose steel structures?

—

where & when use steel structures?

—

main structural types

—

state-of-the-art and prospective market

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What’s steel structure?

architecture → structure →steel structure

Architecture

Structure

What’s steel structure?

definition & scope

STEEL STRUCTURE: a structure which is made from organised combination of structural STEEL members designed to carry loads and provide adequate rigidity

Steel structure PK RC structure

— steel structure, reinforced concrete (RC) structure, concrete-filled-steel tubular (CFT) structure, concrete-filled-steel-RC composite structure?

steel shelf steel furniture ……

Steel structure? Yes, but

steelwork of buildings, bridges and civil eng. works in this course

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What’s steel structure?

definition & scope

steel structures involve sub-structure or members in a building

made from structural steel

SHANGHAI STADIUM

Steel roof + concrete stand

SHANGHAI GRAND THEATER Steel roof + concrete columns

What’s steel structure?

definition & scope

structural member（构件） is physically distinguishable part

of structure with independent structural function, e.g. member (_{杆件)、element(板件)、cable(索) and their combination}

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Why use steel structure?

advantages

; High strength

The high ratio of strength to weight (the strength per unit weight)

; Excellent ductility and seismic resistance

Withstand extensive deformation without failure even under high tensile stress

; Elasticity, uniformity of material

Predictability of properties, close to design assumption

high ratio of strength to weight

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Why use steel structure?

disadvantages

: Susceptibility to corrosion

Maintenance costs / thin-walled structure

: Loss of strength at elevated temperature

Fireproofing costs

: Susceptibility to buckling

Slender member in compression

;

Long-span structures

;

Multi-storey & high-rise buildings

;

Buildings of heavy duty plants

;

Tower & mast structures

;

Portal frames

;

Bridges

;

Infrastructures

;

Deployable structures

;

Generalized structures: mechanical

15 Long-span structures Airport terminals Stadiums Exhibition centres Theatres Train stations

High-rise buildings

Tai-bei 101

CCTV World trade centre

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Tower & Mast structures

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21

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Deployable structures

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Main structural types

buildings and bridges

; truss structures

Bar or truss members

; frame structures

Beams and columns

; grids structures

latticed structure or dome

; arch ; prestressed structures ; beam bridge ; truss bridge truss members ; arch bridge ; cable-stayed bridge ; suspension bridge

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Main structural types

Main structural types

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Main structural types

Main structural types

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Main structural types

Main structural types

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Main structural types

Main structural types

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Main structural types

State-of-the-art & prospective market

technology & economy

; technology

Accurate and automatic fabrication

; economy

Less construction time and less structural weight

; environment

Less wet work

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State-of-the-art & prospective

market for steel structures

2007 y > overall output of the world before 1966 2008 y > 2nd_-8th _output 0 100 200 300 400 500 600

China Japan America Russia India Korea Germany Ukraine

Ra w st ee l ou tp ut , M t 2007 2006 2005 2004 2003 8 7 6 5 4 3 2 42.8 Ucran 48.5 Germany 51.4 Korea 53.1 Italy 72.7 Russia 97.2 USA 120.2 Japan 485.9 Sum. 2~8 Output/Mt Nations No. 489.2 China 1

State-of-the-art & prospective

market for steel structures

Crude steel consumed kg/head

Forecast average 2017 = 550kg/head 2007-2017 750 450 360 Coastal Central Western Regional Kg/head 2006 434 227 170 Coastal Central Western Kg/head 2017 National average 2007 = 340kg/head

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State-of-the-art & prospective

market for steel structures

中国建筑业房屋竣工面积 2004 128163 2000 80715 0 2 0 0 0 0 4 0 0 0 0 6 0 0 0 0 8 0 0 0 0 1 0 0 0 0 0 1 2 0 0 0 0 1 4 0 0 0 0 1985 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 万平米 Steel structure 2%→4% 0 50,000 100,000 1960 1970 1980 1990 2000 Ｋ㎡ Wooden Steel R.C Steel R.COthers year steel structure R.C structure M/ton ↑JAPAN

↓CHINA steel used in buildings

Design concept & rationale

ensure strength, stability and stiffness Stiff

Strength stability Light

All OK !

Not stiff enough (need bigger E)

Not strong enough (need bigger σ_y ) Not stable enough

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Design concept & rationale

metallurgy Steel fabrication Member + connection erection structural system Loads ac tio_n

Strength, stability , rigidity Force, deformation

S ≤ R

Performance required:

Design concept & rationale

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Design concept & rationale

element member restraint connection loading actions ? ? ? Analytical model

Design concept & rationale

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Design concept & rationale

metallurgy Steel fabrication Member + connection erection structural system Loads ac tio_n

Strength, stability , rigidity Force, deformation

S ≤ R

Performance:

Design concept & rationale

metallurgy Steel

fabrication Member + connection

Strength, stability , rigidity

Mechanics of materials

You got a high level?

Tension member

Compression member Beam

Beam-column connection

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Design concept & rationale

S≤R fR R fs S Ra Rn Sa Sn SnRn objective Rd-Sd 0 Sn≤Rn Sn Rn Sd≤Rd subjective Acceptable:

point of view of safety point of view of economy

Design concept & rationale

f

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;

brittle / ductile fracture of steel

members or connections

;

global buckling of structures/members

;

local buckling

;

excessive development of plastic

deformation

;

loss of geometry stability

;

fatigue failure

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brittle / ductile fracture of steel members or connections

global buckling of structures/members

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local buckling

excessive development of plastic deformation

possible failure modes

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;

loss of geometry stability

;

fatigue failure

your task:

Prevent all these failure modes