Design Steps of Singly Reinforced Section

1. Calculate design/factored/Ultimate BM from Service/Working/Characteristics Moment.
2. Calculate Limiting Moment of Resistance for given section. [ MoR,lim = Qbd² ]
3. If BMu > MoR,lim; Provide doubly Reinforced section. If BMu < MoR,lim; Provide Under reinforced Section.
4. BMu = MoR (from Compression Side), BMu = 0.36 f_ck X_u b (d-0.42 X_u)
5. Compute Ast from C=T, 0.36 f_ck X_u b = 0.87 f_y Ast, or instead of step 4 and 5,

6. Area of steel is to be checked for its permissible limit

---

Case 2 : When Section size & area of steel are to be calculated

1. Calculate factored/ Ultimate design BM
2. Assume suitable of b/d ratio.

Lateral buckling : 0.3<b/d<0.7 (uneconomical)

In general, b/d = 0.5

3. The beam size may be considered as any of the following , 115mm, 250mm, 300mm, 350mm etc.

4. Provide d slightly greater than d calculated. generally, d = 1.05 * d,calculated (This is done to keep section under-reinforced)

5. To compute dreqrd for balanced section,

BMu = MoR, lim

BMu = Qlim bd²

6. For Ast,

BMu = C X LA = 0.36 f_ck X_u b (d-0.42 X_u)