Introduction to steel structures

1. Steel structures
SUKHDARSHAN

2. WHAT ARE STEEL STRUCTURES
?
 A structure which is made from organised combination of structural STEEL
members designed to carry loads and provide adequate rigidity
Steel structures involve a sub-structure or members in a building made
from structural steel.
Some famous steel structures are-
WALT DISNEY CONCERT HALL,US TYNE BRIDGE,UK HOWRAH BRIDGE,INDIA

3. ELEMENTS IN A STEEL STRUCTURE
Structural member is physically distinguishable
part of structure with independent structural
function, e.g. member
elements,cable,beams,sections etc

4. ADVANTAGES OF USING STEEL IN
STRUCTURES
 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
 Ease of fabrication and speed of erection

5. The specific strength is a material's strength (force
per unit area at failure) divided by its density. It is
also known as the strength-to-weight
ratio or strength/weight ratio. In fiber or textile
applications
STEEL

6. MOST IMPORTANT
Steel structures facilitate ease of fabrication and faster
erection of structure .Bolts and welding employed for
joining .

7. DISADVANTAGES OF USING STEEL IN A
STRUCTURE
• Susceptibility to corrosion
• Maintenance costs / thin-walled structure
• Loss of strength at elevated temperature
• Fireproofing costs
• Susceptibility to buckling
• Fatigue and brittle fracture
Bucling
phenomenon

8. Where & when use steel structures?
1) Long-span structures
2)Multi-storey & high-rise buildings
3) Buildings of heavy duty plants
4)Tower & mast structures
5)Portal frames
6)Bridges
7)Infrastructures
8)Deployable structures
9)Generalized structures: mechanical

9. HOWRAH BRIDGE
STEEL MARVEL OF INDIA
When commissioned in 1943, Howrah was the 3rd-longest cantilever bridge
in the world

10. What Is a cantilever bridge?

14. General Terms
1) Rivets are a permanent mechanical fastener. Before being installed a rivet
consists of a smooth cylindrical shaft with a head on one end.
1
2) A panel joint is a point of connection
between two or more members of a truss.
Also called node.
2
3) A girder is a support beam used in construction. Girders often
have an I-beam cross section for strength.
3
4) A Pin and Hanger assembly is used to connect two plate
girders of bridges. These assemblies are used when the space
between two bridge piers is too wide to be spanned by a single
set of girders

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16. 4
4) Strings are projections used for
supporting the deck of a bridge
5) A bridge deck or road bed is the roadway, or the
pedestrian walkway, surface of a bridge. It is not to be
confused with any deck of a ship
5

17. 6) An expansion joint or movement joint is an assembly designed to safely
absorb the heat-induced expansion and contraction of construction materials,
to absorb vibration, to hold parts together, or to allow movement due to
ground settlement or earthquakes
6
7) Movement occurs for many different reasons, including
variations in climate or temperature, movement in the frame and
movement in the foundations. Articulation joints are tied at specific
intervals and sealed with filler.
7

18. 8) Mild steel, also called plain-carbon steel, is the most common form of steel
because its price is relatively low while it provides material properties that are
acceptable for many applications, more so than iron. Low-carbon steel contains
approximately 0.05–0.3% carbon
9) An I-beam, also known as H-beam is a beam with an I- or H-shaped cross-
section. The horizontal elements of the “I" are flanges, while the vertical
element is termed the "web".
The web resists shear forces, while the flanges resist most of the bending
moment experienced by the beam. Beam theory shows that the I-shaped
section is a very efficient form for carrying both bending and shear loads in the
plane of the web
8
9

19. Construction

20. TECHNICAL DETAILS
1) Official name- Rabindra Setu
2) Carries -8 lanes of Strand Road, pedestrians and bicycle path
3) Crosses -Hooghly River
4) Locale -Howrah and Kolkata
5) Maintained by- Kolkata Port Trust
6) Designer -Rendel, Palmer and Tritton
7) Design -Suspension type Balanced Cantilever
8) Material -Steel(MILD)
9) Span-705 m (2,313.0 ft)
10) Width -71 ft (21.6 m) with two footpaths of 15 ft (4.6 m) on either side[5]
11) Height -82 m (269.0 ft)
12) Longest span -1,500 ft (457.2 m)
13) Vertical clearance -5.8 m (19.0 ft)
14) Clearance below -8.8 m (28.9 ft)
15) Construction begin -1936
16) Construction end -1942

21. Bridge Details
• Bridge type : Suspension type Balanced Cantilever
• Total span - 2,313.0 ft.
• Anchor arms of 325ft each side
• Main towers are 280ft high above the monoliths and 76 ft apart at the top
• Bridge deck width 71 ft with two footpaths of 15 ft either side
• Longest span- 1,500 ft. (457.2 m)
• Main span- 1663 ft.
• Freeboard for river traffic is 8.8 m
• Other features of the Bridge
• All members of the super structure comprise built up riveted sections with a combination of high
tensile and mild steel
• Deck hangs from panel points in the lower chord of the main trusses with a series of hangers(39 pairs)
• Road way beyond the tower is supported on ground leaving anchor arm free from deck loads
• Bridge deck comprises 71 ft carriage way and 15 ft footway projecting either side of the trusses and
braced by a longitudinal girder.

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23. More about the Bridge
• The deck system consists of cross girders hung between pairs of hangers with
pinned connection.
• Six rows of longitudinal stringer girders span between cross girder.
• Floor joists supported transversely on top of stringers.
They support a continuous pressed steel troughing system.
Over which deck concrete is laid out.
• Joint System of Bridge (Expansion Joints)
• Longitudinal expansion and lateral sway movement of the deck are taken care
of by expansion and articulation joints.
• There are two main expansion joints, one at each interface between the
suspended span and the cantilever arms.
• There are expansion joints at the towers and at the interface of steel and
concrete structures at both approach.

24. • Articulation Joints
• There are total 8 articulation joints.
• 3 at each of the cantilever arms.
• 2 in the suspended portions.
• They divide the bridge into segments with vertical pin connection between them to facilitate
rotational movements of the deck.
• Camber and Traffic clearance
• Bridge deck has longitudinal ruling gradient of 1 in 40 from either endThey are joined by a
vertical curve of radius 4000 ft.
• Cross gradient of deck is 1 in 48 between kerbs and central 4.9mtr. is level to provide tramway
housing channel in between troughing.
• Foundation
• The main tower is founded with single monoliths which are 55.31 x 24.8 m in plan with 21
chambers
• Monoliths at Calcutta and Howrah side are founded 31.41 m and 26.53 m in below ground
level respectively.
• Minimum headroom in carriageway is 5.8 m

25. THANK YOU