In case of a simply supported I-section beam of span L and loaded with a central load W, the length of elasto-plastic zone of the plastic hinge, is

m₁ and m₂ are the members of two individual simple trusses of a compound truss. The compound truss will be rigid and determinate if

If the strain energy stored per unit volume in a hollow shaft subjected to a pure torque when t attains maximum shear stress f_s the ratio of inner diameter to outer diameter, is

The strain energy due to volumetric strain

The maximum deflection of a simply supported beam of span L, carrying an isolated load at the centre of the span ; flexural rigidity being EI, is