Consider a reinforcing bar embedded in concrete. In a marine environment this bar undergoes uniform corrosion, which leads to deposition of corrosion products on its surface and an increase in apparent volume of the bar. This subjects the surrounding concrete to expansive pressure. As a result, corrosion cracks appear at surface of concrete. Which of the following statement is true?

The adjoining figure shows a schematic representation of a steel plate girder to be used as a simply supported beam with a concentrated load. For stiffeners, $$PQ$$ (running along the beam axis) and $$RS$$ (running between the top and bottom flanges) which of the following pairs of statements will be TRUE?

For the fillet weld of size $$'S'$$ shown in the adjoining figure the effective throat thickness is

A disc of radius $$'r'$$ has a hole of radius $$'r/2'$$ cut-out as shown. The centroid of the remaining disc (shaded portion) at a radial distance from the center $$''O''$$ is