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Steel Structures

Steel Structures. Introduction Standard Steel Sections Connections. Introduction. Ever since steel began to be used in the construction of structures, it has made possible some of the grandest structures both in the past and also in the present day.

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Steel Structures

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  1. Steel Structures Introduction Standard Steel Sections Connections Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  2. Introduction • Ever since steel began to be used in the construction of structures, it has made possible some of the grandest structures both in the past and also in the present day. • Structural steel is widely used in making: • Bridges • Transmission Towers • Industrial Buildings • Storage Structures…… …… and, Many More. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  3. Golden Gate Bridge, San Francisco Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  4. Howrah Bridge, Kolkata Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  5. Eiffel Tower, Paris Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  6. Olympic Stadium, London Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  7. Inland Steel Building, Chicago Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  8. An Industrial Shed Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  9. A Refinery Structure Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  10. A Railway Platform Shed Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  11. A Steel Water Tank Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  12. Design Objective • The objective of design is the achievement of an acceptable probability that structures will perform satisfactorily for the intended purpose during the design life. • With an appropriate degree of safety, they should sustain all the loads and deformations, during construction and use and have adequate resistance to certain expected accidental loads and tire. • Structure should be stable and have alternate load paths to prevent disproportionate overall collapse under accidental loading. • All the designs shall confirm to IS 800 : 2007 (Indian Standard ; General Construction in Steel – Code of Practice.) Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  13. Advantages of Steel Structures • High Strength - about ten times that of concrete. • Predictable material properties • Rapid & High Quality Construction. • Ductile and Robust. • Good fatigue strength. • Can be easily repaired and retrofitted. • Can be easily dismantled and sold as scrap. • Durable – Long service life. • Adaptation of prefabrication. • Higher reliability and safety. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  14. Disadvantages of Steel Structures • High Cost of material. • Skilled workmanship & supervision needed. • Regular maintenance required. • Susceptibility to buckling. • Less resistant to fire attacks. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  15. Structural Steel • The steel used for structural works shall confirm to IS 2062 : 2011 (Hot Rolled Medium and High Tensile Structural Steel). • Most Commonly used grade is E-250 (Fe 410). • Following are few important Physical properties of structural steel : • Unit mass of steel, ρ = 7850 kg/m3 • Modulus of elasticity, E = 2.0 x 105 N/mm2 • Poisson’s ratio, µ = 0.3 • Modulus of rigidity, G = 0.769 x 105 N/mm2 • Co-efficient of thermal expansion α.= 12 x 10-6 /oc Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  16. Standard Steel sections • Different Hot Rolled steel sections are used in combination, or, separately to fulfill the design requirements. These standard sections are: • Indian Standard I – Sections • Indian Standard Angle Sections • Indian Standard Channel Sections • Indian Standard T – Sections • Indian Standard Flats • For the sectional properties, references are: • SP : 6 (1) - 1964 (Reaffirmed 2003) • IS 808 : 1989 (Reaffirmed 2004) • Steel Tables of any standard publication. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  17. I - section Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  18. EQUAL ANGLE section Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  19. UNEQUAL ANGLE section Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  20. CHANNEL section Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  21. T - section Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  22. Connections • The different structural components are to be connected together, so as to achieve the final shape of the structure. • The design of connections is having equal importance, as the loads from one component to other are transferred through connections. • Following are the type of connections used in structural steel fabrication: • Riveted Connections. • Bolted Connections. • Welded Connections. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  23. Riveted Connections • Rivet is a pin having a head on one end, inserted through aligned holes in the pieces to be joined and then hammered on the plain end so as to form a second head. • Usually rivet is made up of wrought iron or soft steel due to lower hardness which is necessary to have easy deformation during riveting. • For riveting parts to be joined are first drilled with the help of drilling machine. Clearance is taken into consideration while riveting because by pressing application diameter of rivet is somewhat increased. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  24. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  25. The connection formed by rivets is permanent. • Rivets are widely used in Steel Bridges, trusses, water tanks, silos & boilers. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  26. Advantages of Riveted connections • Cheaper fabrication cost. • Low maintenance cost. • Dissimilar metals can also be joined, even non-metallic joints are possible with riveted joints. • Ease of riveting process. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  27. Disadvantages of Riveted connections • Skilled workers required. • Leakage may be a problem for this type of joints, but this is overcome by special techniques. • The process of riveting is noisy. Due to these disadvantages, rivets are becoming obsolete now a days. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  28. Bolted Connections • A bolt is an externally threaded fastener designed for insertion through holes in assembled parts, and is normally intended to be tightened or released by torquing a nut. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  29. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  30. Advantages of BOLTED connections • Noiseless & quick process. • Only semi-skilled labour required. • No special equipments needed. • Cooling period is not required, as in weld or rivets. • Bolts can be easily disconnected for replacement of damaged parts. • Reliable under fluctuating stresses. • No heat damage to the coating on hot dip galvanized or painted structures. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  31. Disadvantages of BOLTED connections • May be visually unacceptable. • Deduction for holes is required in calculation of area for tension members, which leads to the use of a larger cross section. • Bolts may be prone to corrosion if not properly protected. • Vibrations may lead to loosening of nuts. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  32. Welded Connections • Welding is a procedure that involves fusing two pieces of steel together by melting a sacrificial “flux” electrode to two pieces, thereby joining the pieces permanently together. • The most common type of fillet welding process is “Arc” welding, or sometime called “stick” welding. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  33. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  34. Advantages of WELDED connections • Welded joints are more rigid than bolted joints. • Can directly connect pieces without the need for connection plates. • Welds do not create holes in member (i.e., no need to check fracture on net area) • Can join odd-shaped pieces together. • Adaptable to confined spaces and remote locations. • A high quality weld can often be stronger than the parts to be joined. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  35. Disadvantages of WELDED connections • Welds are brittle, not ductile like bolted connections. • Very labor intensive. • Skilled labor required. • Quality control is difficult to inspect. • Potential fire hazard in areas of welding. • Welding creates a permanent joint, not desirable if parts need to be fixed or replaced later. • Welding very thin sheets is difficult. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  36. Hey…. Yet Not Over…… Wait…. It’s time for something Yummy…….. But... One has to win them in a ….. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  37. 1. Identify the structure…. It’s – “The Golden Gate Bridge, San Francisco” Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  38. 2.The Indian Standard Code of Practice used for General Construction in Steel is….. IS 800 : 2007 Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  39. 3. The Most Commonly used grade of steel in structural work is…… E-250 (Fe 410) Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  40. 4.The unit mass of structural steel is…… 7850 kg/m3 Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  41. 5. The most common type of fillet welding process is….. Arc welding Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

  42. Thanks……. ……. For Your Attention. Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

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