95
Introduction to Civil Engineering Metal Structures Tomasz Michałowski, PhD http://footbridge.pl/stud/ not www.footbridge.pl/stud
Introduction to Civil Engineering
Metal Structures
Tomasz Michałowski, PhD
http://footbridge.pl/stud/
not www.footbridge.pl/stud
Contents
History of civil engineering → 3
Buildings and structures → 9
Model of material → 38
Steel structures, general information → 62
History of civil engineering
The oldest structural materials - animals and branches (> 70 000 years ago).
Photo: tygodnikpowszechny.pl
Photo: glos-tn.krakow.pl
Photo: theguardian.comPhoto: my-cottage-life-bubisa.blogspot.com
Branches - the product of easy processing by tools;
Timber elements - the product of advanced processing by tools (carpentry);
The oldest - probably ~ 14 000 years ago (neolitic revolution);
The oldest known - 7 000 years ago, Liepzig;
The oldest still used - 641 A.C. Lhasa
Timber
Photo: wikipediaPhoto: sciencedaily.com
Photo: true-roots.co.uk
Photo: pl.123rf.com
Stone
The oldest known - 9 500 years ago, Gobekli Tepe; Photo: wikipedia
Photo: archeowieści
Photo: wikipedia
Concrete
The oldest known (lime mortar) - 9 000 years ago, Yiftahel;
Widely use (mixing lime mortar and volcanic rock powder) - 150 B.C. Rome;
Reinforced concrete - 1875 A.C. France;
Photo: wikipedia
Photo: betonowywojtek.pl
Photo: wikipediaPhoto: researchgate.net
Brick
The oldest known (mud brick) - 9 000 years ago, Jeriho, Catal Hoyuk;
Photo: bible-architecture.info
Photo: catalhoyuk.tumblr.com
Photo: thinglink.comPhoto: waa.ox.ac.uk
Metals
The oldest use - monuments; the oldest known:
brozne 530 B.C. Pireus;
iron 415 A.C. Delhi;
First iron structure - 1777 A.C. Coalbrookdale;
Photo: wikipedia
Photo: wikipedia
Photo: ancient-greece.org
Buildings and structures
Building - a man-made structure with a roof and walls standing more or less
permanently in one place.
Non-building structure - man-made formations, that does not necessarily have walls;
Structure - each man-made formations (buildings + n-b structures).
Buildings
Photo: wikipedia
Non-building structures
Photo: wikipedia, Renewables International, Power Engineering International
Types of structures
The structure can be divided according to various criteria, i.e.:
• Need for and use of structures (15 - 19);
• Types of using (20);
• Materials (21 - 28);
• Way to bear loads (29 - 34);
Need for and use of structures:
• To enclose space for environmental control;
• To support people, equipment, materials etc. at required locations in space;
• To contain and retain materials;
• To transport of people, equipment etc;
Enclose space
Photo: wikipedia
Photo: uniserv.com.pl
Photo: dgelpro.pl
Support
Photo: sbdbi.pl
Photo: thecoolimages.net
Photo: wikipedia
Contain
Photo: grupabieszczady.pl
Photo: realizacje.mz.plPhoto: grupab2.pl
Transport
Photo: wikipedia
Photo: inzynieria.com
Photo: Carrasquillo Associates LTD
Photo: Iniekt System
Photo: wikipedia
Types of using
A general classification is:
• residential: houses, apartments, hotels;
• commercial: offices, banks, department stores, shopping centres;
• institutional: schools, universities, hospitals, gaols;
• exhibition: churches, theatres, museums, art galleries, leisure centres, sports stadia, etc.;
• industrial: factories, warehouses, power stations, steelworks, aircraft hangers etc.
Other important engineering structures are:
• bridges - truss, girder, arch, cable suspended, suspension;
• towers - water towers, pylons, lighting towers etc.;
• special structures - offshore structures, carparks, radio telescopes, mine headframes etc.
Materials
Each types of structures can be constructed using a variety of materials, structural
forms or systems. Generaly, each structure consist on various materials (for
example: steel main frames, concrete foundations, concrete floor plates, masonry
external walls).
Composite structure steel - concrete
Photo: topcon.cz
Masonry wall, concrete ring beam, steel
girder
Timber structure with steel tie-bars
Photo: steelmastersnyc.com
Photo: atimber.com
Concrete wall, steel girder, timber
secondary beams
Photo: studio-tm.com
Masonry walls, concrete floor slabs,
concrete base
Photo: understandconstruction.com
Steel frame, concrete base, masonry external walls, concrete floor slabs, sandwich panels
on roof
Photo: malayalamexpress.in
Reinforced concrete frame, masonry external walls, concrete floor slabs, concrete base
Photo: gharpedia.com
Steel column, steel anchor bolts, concrete
base
Photo: civil-engg-world.blogspot.comPhoto: civil-engg-world.blogspot.com
Way to bear loads
1. Massive structures - loadbearing walls resist loads transmitted to them by floor
slabs. Stability depends on gravity loads and internal friction.
2. Framed structures - a steel or concrete skeleton collects loads from plate elements
and delivers them to the foundations.
3. Shell structures - a curved surface covers space and carries loads.
4. Tension structures - cables span between anchor structures carrying membranes or
other members.
5. Pneumatic structures - a membrane sealed to the ground is supported by internal air
pressure.
Gravity masonry structures
Photo: understandconstruction.com
Photo: Author
Framed structures
Photo: carsonconcrete.net
Photo: atechleader.com
Photo: Author
Shell structures
Photo: gpd24.pl
Photo: uniserv.com.pl
Photo: Author
Tension structures
Photo: greatbritain.pinger.pl
Photo: wikipedia
Photo: Author
Pneumatic structuresPhoto: rzeszow-news.pl
Photo: archiexpo.com
Photo: Author
Types of structural members
Bar (1D) member: b ≈ h << l
Plate (2D) member: t << l1 ≈ l2
Photo: archiexpo.com
Photo: archeli.com.au
Photo: top-slab.co.za
Photo: corrugatedsteelsheet.com
Concrete - massive cross-sections
Photo: archiexpo.com
Photo: informedinfrastructure.com
Timber - massive cross-sections
Photo: msennik.pl
Photo: pinterest.com
Steel - slender cross-sections, thin-
walled sections
Photo: designtoeurocodes.com
Photo: thepthienphuc.com
Timber
• Biological
humidity is important for strength
characteristics
• Heterogenous
tensile strength is different than
compression strength
• Anisotropic
strength characteristics depend on
the directions
Model of material
Photo: Author
Concrete
• Heterogenous
tensile strength is different than
compression strength
• Isotropic
strength characteristics are the
same in each directions
Photo: Author
Ceramics
• Heterogenous
tensile strength is different than
compression strength
• Isotropic
strength characteristics are the
same in each directions
Photo: Author
Metals
• Homogenous
tensile strength is the same as
compression strength; fy
• Isotropic
strength characteristics are the
same in each directions
Photo: Author
Metals as structural materials:
Steel ~95% metal structures
Aluminum ~5% metal structures
Concrete ~35% structures
Metals ~35% structures
Masonry ~25% structures
Timber ~5% structures
Metals and other building materials
Material Strength
fy [MPa]
Dead weight
d [kN/m3]
Lightness
k = d / fy [0,001/m]
Steel for tension components
1 450 - 2 300 * 78,5 0,03 - 0,05
High-strength steel 450 - 700 78,5 0,11 - 0,17
"Normal" steel 235 - 355 78,5 0,22 - 0,33
Aluminum 110 - 280 27,0 0,10 - 0,25
Concrete 30 - 50 ** 25,0 0,50 - 0,83
Ceramics 5 - 20 ** 20,0 1,00 - 4,00
Timber 5 - 10 7,0 0,70 - 1,40
* fu**resistance for compression
Vertical cantilever - axial force from dead weight
Nmax (x) = N (0) = A l d
smax = Nmax / A = l d
smax ≤ fy
l = max ↔ smax = fy
lmax d = fy
lmax = fy / d = 1 / k
Photo: Author
Photo: Author
lmax [m]
Steel for tension components *
18 500 - 29 300
High-strength steel 5 900 - 9 100
"Normal" steel 3 000 - 4 500
Aluminum 4 000 - 10 000
Concrete ** 1 200 - 2 000
Ceramics ** 250 - 1 000
Timber 700 - 1 400
* fu**resistance for compression
The highest structures for centuries
Photo: Author1200 1300 1400 1500 1600 1700 1800 1900
400
300
200
100
year
heigh [m]
Stone structure
Brick structure
Steel structure
1
10
12 3 4
5
1. Cheops Pyramid 2. Old London Cathedral 3. Lincoln Cathedral 4. St Olaf's Church, Tallin 5. St Mary's Church, Stralsund 1. Cheops Pyramid 6. St Nicholas's Church, Hamburg 7. Rouen Cathedral 8. Cologne Cathedral 9. Washington Monument 10. Eiffel Tower
6, 7, 8, 9160,0 m 169,3 m
324,0 m
Cheops Pyramid and Eiffel Tower
Photo: Author
Structure:
base 230x230 m
height 146 m
Structure:
base 125x125 m
height 324 m
Volume of material:
base 125x125 m
height 165 m
Volume of material:
base 125x125 m
height 0,08 m
Strength
• f (tension) = f (compression)
• f the same in each direction
Homogenous, isotropic
Analyse of mechanical parameters for steel
Photo: Author
Universal testing machine
Photo: Author
Photo: feiplar.com.br
aluminum
special steel
structural steel
Photo: Author
Photo: Konstrukcje stalowe, K. Rykaluk,
Dolnośląskie Wydawnictwo Edukacyjne
Wrocław 2001
Ainitial
Apresent
Re min / max
Rm
Ru
For example:
Re = 285 MPa
Rm = 400 MPa
fy = ?
fu = ?
Re → fy yeld strength
Rm → fu ultimate tensile strength
Analysis of results
# Re [MPa] Rm [MPa]
1 360,3 530,5
2 306,3 437,6
3 291,2 509,2
4 313,4 431,9
5 247,2 480,3
... ... ...
60 286,8 431,8
Results – for example 60 specimens
f(x) =
x = Re,i
mRe = (S Re,i) / n (average)
sRe = {[S (Re,i - mRe)2] / n} (standard deviation)
This type of results we can described by a normal distribution:
mRe = 297,6 MPa
sRe = 23,4 MPa
Area under red curve = 1
Total height of the bars = 1
Photo: Author
fy ≠ mRe
Average → for 50% elements f < faverage
50% of structures woud have strength less than we assume in calculations!
Photo: rcnkonstantynow.pl
Photo: wiadomosci.wp.pl
Photo: biznes.newsweek.pl
Characteristic value fyk = value, for which only 5% reults are less.
Designing value fy = characteristic / safety factor
Photo: wikipedia
average = 297,65%-quantile = 259,1
fy = 235,5
Photo: Author
max = 360,9
min = 247,2
Summation:
Photo: Author
atg a = E
s
e
Re
Rm
Re - aver
Rm - aver
Test:Statistical analysis:
fyk
fy = fyk / gM
5%
5%
fuk
fu = fuk / gM
Idealization (EN 1993-1-1):
Photo: EN 1993-1-1 fig. 5.3
Structural steels are alloys of iron, with carefully controlled amounts of carbon and
various other metals such as:
manganese, chromium, aluminium, vanadium, molybdenum, neobium and copper.
The carbon content is less than 0.25%,
The manganese less than 1.6% .
Examples of chemical composition for diferent grades of steel:
Steel C [%] Simax [%] Mnmax [%] Pmax [%] Smax [%] Nmax [%] Cumax [%]
t ≤ 16 mm 16 < t ≤ 40 mm
t > 40 mm
S235 JR 0,170 0,170 0,200 0,000 1,400 0,035 0,035 0,012 0,550
S235 J0 0,170 0,170 0,17 0,000 1,400 0,030 0,030 0,012 0,550
S275 JR 0,210 0,210 0,220 0,000 1,500 0,035 0,035 0,012 0,550
S275 J2 0,180 0,180 0,180 0,000 1,500 0,025 0,025 0,000 0,550
S355 JR 0,240 0,240 0,240 0,550 1,600 0,035 0,035 0,012 0,550
S355 JR 0,200 0,200 0,220 0,550 1,600 0,035 0,035 0,012 0,550
Steel structures, general information
• single-storey, single- or multibay structures which may be of truss
• multistorey, single- or multibay structures of braced or rigid frame construction
• space structures (space decks, domes, towers etc.)
• tension structures and cable-supported roof structures;
• shell structures;
Single-storey frame
Photo: Trasko-Stal Sp. z o. o.
Multistorey structures
Photo: skyscrapercity.com
Dome, spatian truss
Photo: wikipedia
Photo: Lianfa Steel Structure
Tension structures
Photo: gwe24.pl
Photo: wikipedia
Shell structures
Photo: Iniekt System
Photo: Carrasquillo Associates LTD
Photo: gpd24.pl
The prime purpose of each structure is to carry loads and transfer them to the ground.
Loads
Cross-sectional froces
ReactionsPhoto: Author
Eurocodes:
• EN 1990 Basis of structural design (one sub-part)
• EN 1991 Actions on structures (ten sub-parts)
• EN 1992 Design of concrete structures (four sub-parts)
• EN 1993 Design of steel structures (twenty sub-parts)
• EN 1994 Design of composite steel and concrete structures (three sub-parts)
• EN 1995 Design of timber structures (three sub-parts)
• EN 1996 Design of masonry structures (four sub-parts)
• EN 1997 Geotechnical design (two sub-parts)
• EN 1998 Design of structures for earthquake resistance (six sub-parts)
• EN 1999 Design of aluminum structures (five sub-parts)
S = 58 sub-parts
General rules: EN 1990;
Loads: EN 1991 (dead weight, live loads, climatics, etc.), EN 1998 (earthquakes);
Cross-sectional forces, reactions : static calculations;
Resistance of structures: EN 1992 (concrete), EN 1993 (steel), EN 1994 (composite
steel-concrete), EN 1995 (timber), EN 1996 (masonry), EN 1999 (aluminum);
Foundations, cooperation with the ground: EN 1997;
Analyse:
Photo: Author
EN 1993 Design of steel structures(common name: Eurocode 3)
1993-1 General rules:
1993-1-1 General rules and rules for buildings
1993-1-2 Structural fire design
1993-1-3 Supplementary rules for cold-formed members and sheeting
1993-1-4 Supplementary rules for stainless steels
1993-1-5 Plated structural elements
1993-1-6 Strength and stability of shell structures
1993-1-7 Plated structures subject to out of plane loading
1993-1-8 Design of joints
1993-1-9 Fatigue
1993-1-10 Material toughness and through-thickness properties
1993-1-11 Design of structures with tension components
1993-1-12 Additional rules for the extension of EN 1993 up to steel grades S 700
EN 1993 Design of steel structures
1993-2 Steel bridges
1993-3 Towers, masts and chimneys :
1993-3-1 Towers and masts
1993-3-2 Chimneys
1993-4 Silos, tanks and pipelines:
1993-4-1 Silos
1993-4-2 Tanks
1993-4-3 Pipelines
1993-5 Piling
1993-6 Crane supporting structures
EN 1999 Design of aluminiuml structures(common name: Eurocode 9)
1999-1-1 General structural rules
1999-1-2 Structural fire design
1999-1-3 Structures susceptible to fatigue
1999-1-4 Cold-formed structural sheeting
1999-1-5 Shell structures
Tσ =
s11 τ12 τ13
τ21 s22 τ23
τ31 τ32 s33
Level of point:
σHMH = √[σ112 + σ22
2 + σ332 - σ11 σ22 - σ11 σ33 - σ22 σ33 + 3(τ12
2 + τ232 + τ13
2 )]
σHMH / fy ≤ 1,0
σHMH = √[σ2 + 3(τ12 + τ2
2)]
Welded connectionsShells, fatigue calculations, crane supporting structures
Types of formulas - different for different level of structure
F - geometry of cross-section
R = F fy
E / R ≤ 1,0
Elements, nodes - when instability is not important, bolts, rivets, pins
Level of cross-sections:
Photo: Author
Level of elements:
F - geometry of cross-section
χ - instability coefficient (depends on element geometry)
R = χ F fy
E / R ≤ 1,0
Elements, nodes - when instability is important
Photo: Author
Parts of metal structure
Each steel structure can be divided
into three parts:
• members
• connections
• joints
Photo: Author
Members
Bars, beams, purlins, rafters, girders, columns,
bracings... – global destruction
Photo: Author
Photo: civildigital.com
ConnectionsWelds and shank of bolts – local („in point”) destruction
Photo: Author
Photo: ceprofs.civil.tamu.edu
Photo: researchgate.net
Joints Small parts of members, where are contact between two or
more members. There are many specific phenomenons on
these short part of beams, columns, etc. Local („in area”)
destruction.
Photo: Author
Photo: scielo.br
Photo: ascelibrary.org
Photo: thestructuralmadness.com
Photo: osha.gov
Algorithm for metal structure
Photo: Author
What we must to check?
Element Connection Joint
Resistance Cross-sectional forces not
greater than limit; level of
cross-section
Cross-sectional forces or
stresses not greater than
limit; level of point
Cross-sectional forces
not greater than limit;
special formulas
Stability Cross-sectional forces not
greater than limit; level of
element
Not important Cross-sectional forces
not greater than limit;
special formulas
Stiffness Deformations and
displacements not greater
than limits
Not important Classification of joint:
rigid, semi-rigid, pinned
Pinned
Rigid
Semi-rigid
Photo: Author
Only initial, linear part is taken into consideration, this
means inclination of limist 1-2 and 2-3 is calculated.
Static analysis
Reduction of a 3D structure to simpler
2D forms.
This calculation method is used for handmade
calculations. It was the only way +25 years ago,
when computers were not widespread. Today
computer calculations caried out in 3D.
Photo: Author
Calculations: Handmade By computer
2D Acceptable Acceptable
3D Acceptable Recommended
Calculations
Photo: adaptsolutions.files.wordpress.com
Photo: dlubal.com
Elastic
Plastic
Elastic analysis: linear dependence s-e
Plastic analysis: nonlinear dependence s-e
Photo: EN 1993-1-1
Photo: Author
Small deformations - no secondary effects
Big deformations - secondary effects
Photo: masterseries.com
Thanks to computer programs, we are able to analyze complex problems,
but...
Photo: i.ytimg.com
Photo: scadsoft.com
Photo: images.adsttc.com
Photo: ski-consult.de
ATTENTION
Computer is never more clever than its user
Photo: thesaltfactory.org
Photo: genius.com
Photo: wikipedia
Computer always get you back
the same information, that you
put in it, only in other form
Photo: flashbynight.com
Bul%$hit everywhere
Photo: fabrykamemow.pl
Photo: computerhope.com
Photo: images.complex.com
Photo: wonderfulengineering.com
Photo: react.autodesk.com
respectfulinsolence.com
One of the goals of your studies: the ability to
assess the correctness of input and output data
Photo: computerhope.com
Photo: react.autodesk.com
respectfulinsolence.com
Photo: cobaltrecruitment.com
Photo: cobaltrecruitment.com
Photo: cobaltrecruitment.com
Photo: nytimes.com
Photo: dailytimes.com.pk
flashbynight.com
respectfulinsolence.com
But sometime in the future…
Computers still aren't able to make this assessment.
? ? ?
? ? ?
Photo: theartmad.com
HASTA LA VISTA, HUMAN.
YOU LOSE YOUR JOB.
I AM A CHEAPER DESIGNER.
Photo: linkedin.com
Ring beam - wieniec
Girder - dźwigar
Tie-beam – ściąg
Corrugated sheet – blacha fałfowa
Slender - smukły
Thin-walled - cienkościenny
Concrete mass – beton (bez zbrojenia)
Peinforced concrete – żelbet (beton zbrojony)
Prestressed concrete – żelbet sprężony
Cement mortar – zaprawa cementowa
Aggregate - kruszywo
Alloy – stop
Normal distribution - rozkład normalny
Standard deviation - odchylenie standardowe
Reliability – niezawodność
Limit state – stan graniczny
Ultimate l.s. – stan graniczny nośności
Serviceability l.s. – stan graniczny użytkowania
