CHAPTER-3

STEEL STRUCTURE

• Q1: What is Steel Building?
  Ans:A steel building is a metal structure fabricated with steel for the:

  • ➔ Internal support
  • ➔ Exterior cladding

  Such buildings are used for a variety of purposes including storage, office space, and living space.
• Q2: Write the materials used for steel structure.
  Ans:The materials commonly used are:

  • ➔ Cast iron
  • ➔ Wrought iron
  • ➔ Steel
• Q3: Define Cast Iron.
  Ans:Cast iron has a carbon content of 2.5%–4%. It can bear only compressive stresses and is used for compression members only.
• Q4: Define Wrought Iron.
  Ans:Wrought iron has a carbon content of 0.1%. It has a fibrous nature and is suitable for resisting tensile stresses.
• Q5: Define Mild Steel.
  Ans:Mild steel has a carbon content of 0.05%–0.3%. It is suitable for general construction and has largely replaced cast and wrought iron. It performs well in both tension and compression.
• Q6: Why is Cast Iron not used for manufacturing different Steel Members?
  Ans:Cast iron is not used for manufacturing modern steel members (like beams, columns, trusses) due to the following reasons:

  • ➔ Brittle Nature
  • ➔ Weak in Tension
  • ➔ Poor Ductility
  • ➔ Difficult to Weld or Fabricate
• Q7: Define Gusset Plate.
  Ans:Gusset Plate is a thick sheet of metal used to connect beams and columns or to join different structural members in frameworks. It provides extra strength and stability at joints by distributing loads and stresses evenly.
• Q8: Write some advantages of Steel Structure.
  Ans:Advantages include:

  • ➔ High quality and aesthetic
  • ➔ Low maintenance costs
  • ➔ Steel is non-combustible
  • ➔ Environmentally friendly
  • ➔ Components can be reused
• Q9: Write some disadvantages of Steel Structure.
  Ans:Disadvantages include:

  • ➔ Corrosion
  • ➔ High heat conductivity
• Q10: Name some Rolled Steel shapes.
  Ans:Some of the rolled steel shapes are:

  • ➔ Angle section
  • ➔ I-section
  • ➔ T-section
  • ➔ Channel section
  • ➔ Flat bars
  • ➔ Square bars
  • ➔ Round bars
  • ➔ Corrugated sheets
  • ➔ Steel plates
• Q11: Define Channel section.
  Ans:Channel sections consist of a web with two equal flanges and are widely used as structural members in steel-framed structures.
• Q12: Write some uses of the Angle section.
  Ans:Angle sections are used in:

  • ➔ Structural steel-work
  • ➔ Steel roof trusses
  • ➔ Filler joist floors
• Q13: What are corrugated sheets?
  Ans:Corrugated sheets have grooves and are usually galvanized. They are commonly referred to as galvanized iron sheets (G.I. sheets) and are mainly used for roof coverings.
• Q14: What are the properties of corrugated sheets?
  Ans:Some of the properties of corrugated sheets are:

  • ➔ High strength-to-weight ratio
  • ➔ Durable and weather-resistant
  • ➔ Lightweight and easy to install
  • ➔ Available in various materials and sizes
  • ➔ Can provide thermal and sound insulation
  • ➔ Aesthetic appearance with different colors and finishes
• Q15: What are Flat bars?
  Ans:Flat bars are available in widths from 10 mm to 400 mm and thicknesses from 3 mm to 40 mm. They are widely used in steel grill work for windows and gates.
• Q16: What is Ribbed-TOR steel?
  Ans:Ribbed-TOR steel is high-strength deformed steel with ribs or projections, produced by controlled twisting of hot-rolled bars.
• Q17: Write some advantages of Ribbed-TOR steel.
  Ans:Advantages include:

  • ➔ Suitable for major reinforcement structures
  • ➔ Economical and efficient
  • ➔ Requires less labor
  • ➔ Easily bendable up to 180° without cracks
  • ➔ Can withstand great stresses
• Q18: Write the methods used for connecting steel members.
  Ans:Steel members are connected using:

  • ➔ Rivets
  • ➔ Bolts
  • ➔ Welding
• Q19: Define Bolts.
  Ans:Bolts, along with nuts and washers, are used for temporary connections in steel frame structures.
• Q20: Define Rivets.
  Ans:Rivets are made from mild steel round rods and consist of a hemispherical head with a cylindrical shank.
• Q21: State the types of Rivets.
  Ans:Types include:

  • ➔ Round headed
  • ➔ Flat headed
  • ➔ Counter-sunk headed
• Q22: State the process of Welding.
  Ans:Welding is carried out by:

  • ➔ Oxy-acetylene gas welding
  • ➔ Electric arc welding

  Welding rods provide molten metal to fill the joint. In arc welding, a spark is produced between the rod and the surface to be welded.
• Q23: Name some types of Welds.
  Ans:Weld types include:

  • ➔ Butt weld
  • ➔ Lap weld
  • ➔ Fillet
  • ➔ Tee
  • ➔ Edge
  • ➔ Outside corner
• Q24: Define Butt Weld.
  Ans:Butt weld joins plates at their edges with weld metal filling the gap. The type of butt weld used depends on plate thickness and welding accessibility.
• Q25: Define Fillet Weld.
  Ans:A fillet weld is a triangular weld used at the junction of two metal members, typically at a right angle.
• Q26: Why is welding better than riveting?
  Ans:Welding is better than riveting because it gives stronger joints, saves material, is lighter, and provides a leak-proof and smoother finish.
• Q27: State some advantages of Welding.
  Ans:Advantages of welding:

  • ➔ Economical on a large scale
  • ➔ Eliminates riveting noise
  • ➔ No reduction in sectional area
  • ➔ Fast work process
  • ➔ Smooth and aesthetic finish
• Q28: What is buckling in steel columns?
  Ans:Buckling is a failure mode where a slender column bends or collapses under compressive load.
• Q29: What is the purpose of Purlins in steel roof structure?
  Ans:Purlins are horizontal beams that support the roof covering and transfer loads to the main framing.
• Q30: What is the difference between braced and unbraced steel frames?
  Ans:Braced frames use diagonal elements for lateral load resistance; unbraced frames rely on rigid connections for stability.
• Q31: What is the Modulus of elasticity of steel?
  Ans:Approximately 200 GPa or 29,000 ksi.
• Q32: What is meant by plastic design in steel structure?
  Ans:Plastic design allows steel to deform beyond the elastic limit before failure, enabling more efficient designs.
• Q33: What is lacing in steel compression members?
  Ans:Lacing is a technique of connecting multiple compression members (like two I-sections) using flat plates or bars to work as a single unit.
• Q34: Differentiate between Bolts and Rivets.
  Ans:

  Bolts	Rivets
  Provides temporary connection	Provides permanent connection
  Gets loose when subjected to heavy vibration	Never loosens with heavy vibration
  Fast and simple	Time consuming
  Easy to remove and reusable	Needs to be cut out; not reusable

• Q35: Name 2 steel structure/steel buildings.
  Ans:

  • ➔ Eiffel Tower, Paris
  • ➔ Empire State Building, New York
• Q36: Define Truss.
  Ans:A truss is a framework composed of members (arranged in triangles) designed to support loads and span large distances.
• Q37: Define Bracing in steel structure.
  Ans:Bracing in a steel structure is a system of diagonal members used to provide lateral support and prevent deformation due to wind, seismic, or other horizontal forces.
• Q38: Write 2 uses of Corrugated sheets.
  Ans:Corrugated sheets are used as follows:

  • ➔ For roof covering
  • ➔ For shutters
• Q39: Define Counter-sunk rivet.
  Ans:A counter-sunk rivet is a type of rivet with a conical head that fits flush with or below the surface of the material, providing a smooth finish.
• Q40: Define Castella Beam.
  Ans:A Castella Beam is a type of steel beam created by cutting a rolled steel section longitudinally and rejoining it to form a deeper beam with hexagonal or circular openings to reduce weight and allow service ducts.
• Q41: Define Girders.
  Ans:Girders are the main horizontal steel members in a structure that support smaller beams or joists and transfer loads to columns or supports.
• Q42: Define Round Bars.
  Ans:Round bars are long cylindrical steel rods used in construction, manufacturing, and reinforcement due to their strength and versatility.
• Q43: Write the uses of expanded metal sheets.
  Ans:Expanded metal sheets are used as follows:

  • ➔ For making stair treads
  • ➔ For making walkways
  • ➔ For fencing
  • ➔ For making ventilation screens
• Q44: Why Mild steel is used in steel structure?
  Ans:Mild steel is used in steel structure because:

  • ➔ It is ductile
  • ➔ It is economical
  • ➔ It resist both tension and compression
• Q45: Define reinforcement.
  Ans:Reinforcement refers to the steel bars used in concrete to improve its tensile strength and ductility.
• Q46: Define Plain bars.
  Ans:Plain bars are smooth, round steel bars without any surface deformations, commonly used in small concrete works and as dowels in expansion joints.
• Q47: Define Deformed bars.
  Ans:Deformed bars are steel bars with surface ribs or projections that provide more friction and better grip.
• Q48: What is the purpose of ribs in steel bars?
  Ans:Ribs in steel bars increase the bond strength between the steel and concrete. It provides friction and better grip.
• Q49: Define Web.
  Ans:A web is the vertical or central part of a steel section (like an I-beam) that connects the flanges and resists shear forces.
• Q50: Define Flange.
  Ans:A flange is the horizontal or flat part of a steel section (like an I-beam) that resists bending moments and provides strength against compression and tension.
• Q51: Define Medium Carbon steel.
  Ans:Medium carbon steel is steel containing approximately 0.25% to 0.60% carbon. It has strength, hardness, and ductility, making it suitable for shafts, axles, and gears.