Maximum strain at the level of compression steel for a rectangular section having effective cover to compression steel as d' and neutral axis depth from compression face as x_{u} is

The maximum shear stress in a solid shaft of circular cross-section having diameter d subjected to a torque T is τ. If the torque is increased by four times and the diameter of the shaft is increased by two times, the maximum shear stress in the shaft will be

In a drained triaixal compression test, a saturated specimen of a cohesionless sand fails under a deviatoric stress of 3 kgf/cm^{2} when the cell pressure is 1 kgf/cm^{2} . The effective angle of shearing resistance of sand is about