Concepts: The principal mechanical properties of the structural steel important in design, as detailed by the code IS 800:2007 in cl. 2.2.4.2, are: 1. Yield stress 2. Tensile or ultimate stress 3.The maximum percent elongation on a standard gauge length and 4. Notch toughness Note: The various Physical properties of structural steel irrespective of its grade, as detailed by cl.2.2.4.1 of IS 800:2007 are: 1. Unit weight of steel =7850kg∕m3 2. Modulus of elasticity, E=2.0×105N∕mm2 3. Poisson ratio, μ=0.3 4. Modulus of rigidity, G=0.769×105N∕mm2 5. Coefficient of thermal expansion α=12×10−6∕C.