Steel Structures

Steel StructuresIntroductionStandard Steel Sections ConnectionsProf. Sachin Patel (Head, CED) SAMCET, BhopalIntroductionEver 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:BridgesTransmission TowersIndustrial BuildingsStorage Structures and, Many More.

Prof. Sachin Patel (Head, CED) SAMCET, BhopalGolden Gate Bridge, San Francisco

Prof. Sachin Patel (Head, CED) SAMCET, BhopalHowrah Bridge, Kolkata

Prof. Sachin Patel (Head, CED) SAMCET, BhopalEiffel Tower, Paris

Prof. Sachin Patel (Head, CED) SAMCET, BhopalOlympic Stadium, London

Prof. Sachin Patel (Head, CED) SAMCET, BhopalInland Steel Building, Chicago

Prof. Sachin Patel (Head, CED) SAMCET, BhopalAn Industrial Shed

Prof. Sachin Patel (Head, CED) SAMCET, BhopalA Refinery Structure

Prof. Sachin Patel (Head, CED) SAMCET, BhopalA Railway Platform Shed

Prof. Sachin Patel (Head, CED) SAMCET, BhopalA Steel Water Tank

Prof. Sachin Patel (Head, CED) SAMCET, BhopalDesign ObjectiveThe 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, BhopalAdvantages of Steel StructuresHigh Strength - about ten times that of concrete.Predictable material propertiesRapid & 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, BhopalDisadvantages of Steel StructuresHigh Cost of material.Skilled workmanship & supervision needed.Regular maintenance required.Susceptibility to buckling.Less resistant to fire attacks.Prof. Sachin Patel (Head, CED) SAMCET, BhopalStructural SteelThe 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, = 7850 kg/m3Modulus of elasticity, E = 2.0 x 105 N/mm2Poissons ratio, = 0.3Modulus of rigidity, G = 0.769 x 105 N/mm2Co-efficient of thermal expansion .= 12 x 10-6 /oc

Prof. Sachin Patel (Head, CED) SAMCET, BhopalStandard Steel sectionsDifferent Hot Rolled steel sections are used in combination, or, separately to fulfill the design requirements. These standard sections are:Indian Standard I SectionsIndian Standard Angle SectionsIndian Standard Channel SectionsIndian Standard T SectionsIndian Standard FlatsFor 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, BhopalI - section

Prof. Sachin Patel (Head, CED) SAMCET, BhopalEQUAL ANGLE section

Prof. Sachin Patel (Head, CED) SAMCET, BhopalUNEQUAL ANGLE section

Prof. Sachin Patel (Head, CED) SAMCET, BhopalCHANNEL section

Prof. Sachin Patel (Head, CED) SAMCET, BhopalT - section

Prof. Sachin Patel (Head, CED) SAMCET, BhopalConnectionsThe 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, BhopalRiveted ConnectionsRivet 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

Prof. Sachin Patel (Head, CED) SAMCET, Bhopal 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, BhopalAdvantages of Riveted connectionsCheaper 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, BhopalDisadvantages of Riveted connectionsSkilled 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, BhopalBolted ConnectionsA 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

Prof. Sachin Patel (Head, CED) SAMCET, BhopalAdvantages of BOLTED connectionsNoiseless & 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, BhopalDisadvantages of BOLTED connectionsMay 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, BhopalWelded ConnectionsWelding 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

Prof. Sachin Patel (Head, CED) SAMCET, BhopalAdvantages of WELDED connectionsWelded 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, BhopalDisadvantages of WELDED connectionsWelds 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, BhopalHey. Yet Not Over Wait.Its time for something Yummy..

But... One has to win them in a ..Prof. Sachin Patel (Head, CED) SAMCET, Bhopal

1. Identify the structure.Prof. Sachin Patel (Head, CED) SAMCET, BhopalIts The Golden Gate Bridge, San Francisco

2.The Indian Standard Code of Practice used for General Construction in Steel is..

IS 800 : 2007Prof. Sachin Patel (Head, CED) SAMCET, Bhopal3. The Most Commonly used grade of steel in structural work is

E-250 (Fe 410)

Prof. Sachin Patel (Head, CED) SAMCET, Bhopal4.The unit mass of structural steel is

7850 kg/m3

Prof. Sachin Patel (Head, CED) SAMCET, Bhopal5. The most common type of fillet welding process is..

Arc weldingProf. Sachin Patel (Head, CED) SAMCET, BhopalThanks.

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