Correspondence. Distribution of Tensile Stress in Beams

WHILE many advantages of pre-stressed concrete beams over the ordinary reinforced concrete beam, such as reduction of deflections, lighter construction, greater safety against cracks, and possibilities for precast work, have been recognised, there is a widespread fear among engineers that these advantages may be lost due to a considerable loss of prestress in course of time. Uncertainty is also felt about the exact effects of pre-stressing on a normal reinforced concrete beam. Dr. K.L. Rao

Action of the plane polariscope-Behaviour of stressed material in polariscope -Isochromatic and isoclinic lines-The determination of the separate principal stresses- Optical system of a typical polariscope. A.W. Hendry

This month's letters discuss foundations in shrinkable ground and highlight a survey on structural optimisation in practice.