Assumption in theory of simple bending of RCC structure(working stress method) 1. A section which is plane before bending remains plane after bending. 2. The concrete and steel reinforcement are perfectly bonded . 3. All tensile stress are taken up by steel and non by concrete. 4.the stress strain relation of Steel and concrete under working load is a straight line. 5. The modulli of elasticty of Steel and concrete are constant. 6. The modular ratio has the value ,where. Is the permissible compressive strength of concrete in bending in Newton per mm square. 7. There are no initial stress in steel and concrete. CONCEPT OF TRANSFORMED OR EQUIVALENT SECTION ANALYSIS OF SINGLE REINFORCED BEAM A SINGLY REINFORCED BEAM SECTION IS SHOWN IN FIGURE 2.3 (a). To analyse this section it is necessary to convert it into a transformed or equivalent section of concrete.