State the importance of structural element
If this structural element is used as a beam element, subjected to self load and other imposed transverse loads, then the bottom fibres of the beam shall be subjected to tensile stresses and the top ones to the compressive stresses. Resultant stresses at a section due to pre-stressing and external loads are combined stresses. For calculating these combined stresses we separately calculate stresses produced due to prestressing force and externally imposed loads. Then these separately determined stresses are algebraically added to get combined stresses at a section. Therefore, the following relationship for determination of combined stresses at a fibre of a cross-section (produced due to loads and prestressing force) is used for this case of concentric pre-stressing in a beam element.