Design of Steel Structure (General Engineering) (SSC JE)

Bolts may be used in place of rivets for structure not subjected to vibrations.
• Bolts are most suitable to carry axial tension diameter of bolts holes.

As per IS : 800-2007, The limit state method is most widely used for design of steel structures. IS : 800-1984 which is based on elastic method.

• According to IS 800-2007, In the limit state design does not include corrosion and durability.

• As per IS : 800-2007, mechanical properties of the structural steel which is use in design is yield stress, tensile ultimate stress, maximum percent elongation on a standard gauge length and notch toughness.

(i) Increased quantity of carbon and manganese impart higher tensile strength and yield properties but lower ductility, which is more difficult to weld.

(ii) Increased sulpher and phosphorous beyond 0.06% impart brittleness, affects weld ability and fatigue strength.

(iii) Chromium and nickel impart corrosion-resistance property to steel. It improve resistance to high temperature.

(iv) Addition of small quantity of copper also increases the resistance to corrosion.

As per IS : 800-2007, Fillet welds material fails in shear failure. Shear failures occurs when the applied shear stress exceeds the shear strength of the weld material.
• Shear strength of fillet welds affected by following factors-
(i) Welding process
(ii) Welding parameters
(iii) Base metal properties

Tie is a tension member not a compression member.
• Strut, rafter and boom are compression member.

Slenderness ratio–It is the ratio of effective length of member to the radius of gyration of the cross section about the axis under consideration.• Classification of column based of slenderness ratio–
(i) S.R < 32 – Short column
(ii) S.R = 32-120 – Medium column
(iii) S.R > 120 – Long column

Permissible values
Axial tensile stress = 0.6 fᵧ
Bearing stress = 0.75 fᵧ
Maximum permissible average shear stress = 0.4 fᵧ
Maximum permissible shear stress = 0.45 fᵧ