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In many reinforced concrete structures and particularly in floor systems, a concrete slab is cast monolithically with and, connected to, rectangular beams. In such a construction a portion of the slab above the beam behaves structurally as a part of beam in compression. The slab portion is called the flange and beam the web. If the flange projections are on either side of the rectangular web or rib, the resulting cross-section resembles the T-shape and hence is called a T-beam section. On the other hand, if the flange projects on one side, the resulting cross-section resembles an inverted L and hence as L-beam. 2

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CASE I :- X u < D f. The actual neutral axis fall within the flange as shown in fig. and the beam is analyzed as a rectangular beam of width b f instead of a beam of width b w and depth d. 4

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The value of x u in the proceeding expressions must be evaluated by using the internal force equilibrium equations, for which it is essential to assume for the trial that either x u D f. To reduce the calculation for the first trial, assume that the neutral axis coincides with the underneath of the flange slab, and calculate total compression in concrete flange and total tension in steel, C u and T u, respectively. Then 1.If C u > T u, the neutral axis lies in the flange. 2.If C u = T u, the neutral axis coincides with the bottom of the flange. 3.If C u < T u, the neutral axis lies in the web. 8

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