Structural steel

Study of steel structural buildings and its comparison with other building material.

1. A presentation on
Structural Steel
By:
Vinod Singh

2. Steel
Man made metal derived from
iron- which is its major
constituent
Remaining components are small
amounts of other elements
Added to improve the quality of
steel

3. Used as:
Basic products of steel mill such as
plate, section and bars
From this members are fabricated viz.
beams, girders, columns, struts, ties
etc.

4. Steel vs. Cast Iron
Up to 1.5 % Carbon combines with iron
More than 1.5 -4.5 % present as free
graphite – known as cast iron
Properties vary with the varying carbon
content
Increasing carbon content produces increase
in shear strength & hardness
Decreases the ductility and toughness

5. Comparison between Cast Iron, Wrought Iron &
Steel
Comp strength
4.75 -25.2 tonnes/
sq cm
Ultimate tensile
strength is 5.51 to
11.02 t /sq m
compressive
strength is 2.0
tonnes/sq cm and
ultimate tensile
strength 3.15
tonnes/sq cm
Comp. strength
6.3-7.1 tonnes/sq cm
Ultimate tensile
strength 1.26 to
1.57tonnes/sq cm.
Strength
Can be hardened &
tempered
Cannot be
hardened or
tempered
Hard, hardened by
heating & sudden
cooling
Hardness
1300-1400 degree
Celsius
1500 degree
Celsius
1200 degree CelsiusMelting point
Midway Purest
Contains up to
0.25% carbon
Crude form containing
2-4% carbon
composition
SteelWrought ironCast Iron

6. Comparison between Cast Iron, Wrought Iron & Steel
Absorbs shocksCannot stand
heavy shocks
Does not absorb
shocks
Reaction to
sudden shock
Rapidly forged or
welded
Easily forged or
welded
Brittle and
cannot be
welded or rolled
into sheets
Forging &
Welding
Tough, malleable
& Ductile
Tough,
malleable, ductile
& moderately
elastic
Brittle & cannot
be welded or
rolled into sheets
Malleability&Duct
ility
Rusts easilyRusts more than
Cast Iron
Does not rust
easily
Rusting
SteelWrought ironCast Iron

7. Comparison between Cast Iron, Wrought Iron & Steel
Used as
reinforcemen
t in R.B. &
R.C.C.
Used in making
St. members,
bolts, rivets
and sheets
(plain and
corrugated)
Making
cutlery, files
& machine
tools
Costlier than
mild steel so
being replaced
by the latter
Withstand
shocks without
permanent
injury so used
in chains,
crane hooks
and railway
couplings
For parts that
rust easily like
water pipes,
sewers, drain
pipes etc.
Making such
parts of
machines as
are not likely to
be subjects to
shocks or
tension
Lamp posts,
columns and
railings
Uses
SteelWrought ironCast Iron

8. Types of Steel: (According to varying
Carbon Content)
Dead Mild Steel (Less than 0.15 % Carbon )
Mild Steel (0.15 – 0.30 % Carbon)
Medium Carbon Steel (0.30 -0.80 % Carbon)
High Carbon Steel (0.80 -1.50 % Carbon)
Cast Steel / Carbon Tool Steel (More than
1.50 % Carbon)

9. Mild Steel
Ductile & malleable
More tough and more elastic than cast iron and wrought iron
More prone to rusting than wrought iron
Corrodes quickly
Easily forged, welded & riveted
Withstands shocks & impacts well
Not much affected by saline water
Equally strong in tension, compression and in shear
Difficult to harden and temper
Sp. Gravity 7.8

10. Mild Steel : Uses
Used as rolled structural sections like I-
section; T-section; channel Section; angle
irons. Plates round and square rods
M.S. Round bars
Used as reinforcement in R.C.C.
M.S. tubes are used in structures
Plain and Corrugated M.S. Sheets are used in
roofing

11. Medium Carbon Steel
Granular structure
More tough & elastic than M.S.
Easier to harden & to temper
More difficult to to forge and to weld
Stronger in compression than in tension or in
shear
Withstands shocks and vibrations better

12. Medium Carbon Steel : Uses
For making tools such as dills, files,
chisels
Used for making those parts that ae
hard , tough and durable and capable
of withstanding shocks and vibrations

13. High Carbon Steel
Increased tensile strength leads to less
weight of it being used as compared to
M.S.
Structure becomes lighter
Resists corrosion better
Tougher and more elastic
More brittle and less ductile than mild
steel

14. High Carbon Steel : Uses
In reinforcing prestressed concrete
structures

15. Types of Steel:
(according to elements used)
Steels that owe their properties due to
carbon are called Carbon Steels
Steels with properties due to elements
other than carbon are termed as Alloy
Steels

16. Alloy Steels
The elements that impart distinctive characteristics to
steel are added to iron to produce an alloy steel
named after the element added
Prepared to increase strength, hardness, toughness,
resistance to corrosion and thermal and electrical
conductivities
Divided into two categories:
Ferrous alloys ( chromium, nickel, vanadium,
tungsten, molybdenum and manganese )
Non Ferrous alloys

17. Stress strain curve

18. Structural
steel sections
Hot rolled sections

19. Tolerances in structural steel
It is not possible in rolling process to produce
sections to the exact dimensions specified.
Allowances for:
Slight variation in member length
Inaccurate location of holes
Out of squareness of member ends
Variation in depth of welded girders
Other dimensional variations

20. bolting
Most common method in
joining structural is bolting:

21. welding
There are 3 different type
of welds
Butt weld
Fillet weld
Lap weld

22. Properties of a structural steel
frame
In design:
Large spans
With columns of small sections
Great building heights and high loadbearing
capacity
Combined with low dead weight of the
structure
Structural systems in which openings can be
easily provided
To simplify installation of services

23. Properties of a structural steel
frame
In construction:
Prefabrication and erection of components
Shorter construction time
Close dimensional tolerances
Ease in fixing and cladding
Erection independent of weather conditions
Modest demand on space on the site
Dry construction

24. Properties of a structural steel
frame
In use:
Greater flexibility
Limited no. of internal supports
Adaptibility of frame work to change of
use
Increasing effective life of building
Ease in dismantling or demolition

25. Applications
11. Circular vent
12. Vehicle door
13. Pedestrian door
14. Window
15. Roof light
16. Canopy
17. Parapet
18. Crane beams and rails
19. Bridge crane
20.
Mezzanine or Structural Floor
1. Portal Frame - Rafter
2. Portal Frame - Column
3. Wind bracing
4. Purlins
5. Wall Rails
6. Roof panels
7. Wall panels
8. Astrotherm insulation
9. Eave gutter
10. Monovent

26. Applications: Wind Bracing
Wind bracing provides the longitudinal stability of
the building.
It consists of cross bracing located in roof and
sidewalls, in one or more bays depending on
loadings and the length of the building.
 If it is not possible to have cross bracing in the
sidewalls, it can be replaced by wind portal frames
or by fixed base wind columns, located adjacent
and connected to the mainframe columns.

27. Applications: Roof Lights
Roof Lights can be of dome construction as
shown here or as profiled sheets replacing steel
roof panels.
Function
Continuous natural light
General Characteristics
Insulated roof curb
A framed opening of double skin metallic roof curb,
to match the profile of the roof sheet and its
location. Class-fibre insulation is installed on job
site.

28. Applications: Astrotherm
insulation
Astrotherm insulation
consists of fibre glass
blanket complete with a
laminated facing vapour
barrier
 Optionally, isoblocks are
supplied to minimise
thermal bridges and
Alustrip to improve the
overall appearance of any
exposed insulation joints.

29. Eave gutter
Gutters are often an afterthought and
can spoil the appearance of a building
The gutters are large capacity and
colour coated to compliment the
building. Alternatively internal gutters
can be provided

30. Monovent
Used On the peak in the roofs
Function
Ventilation of the building at the ideal peak
position, where large movement of air is
required.
General Characteristics
Steel operating cable, cable guides (instead
of standard type pulleys), hook and cable
stop.
Stainless steel screws and aluminium
rivets.

31. Roof Panels

32. Wall Panels

33. Mezzanine

34. Purlins

35. Bridge crane

36. Circular Vents

37. Pedestrian door
                                                                                                                                                                                                                                                        
                                       

38. Structural steel in buildings
Airport terminal complex

39. A steel joist and king post truss system
provide support for the 650,000sq. ft. roof.

40. This framing system
creates
wide-open, column-free
spaces
king post trusses form the
lateral-force resisting
system, eliminating the
need for bracing and further
increasing flexibility
of the interior space.

41. Steel buildings- stadium

42. The upper tier, cantilevering 46' over the suite and club
Levels
supported by column groupings consisting of four massive
steel HSS placed at the midpoint alternating structural
bays.