Limiting Moment of Resistance of a RCC Beam

The limiting Moment of Resistance of a RCC Beam is given as:

M_u,lim = 0.362Bf_ck X_u,lim (d-0.42 X_u,Lim)

Where symbols have their usual meaning

Further, the X_u,lim/d ratio depends on grade of steel being used, which is referred from the below table:

Grade of Steel	Xu,lim/d
Fe 250	0.53
Fe 400	0.48
Fe 500	0.46

Development Length of Steel bar in RCC

Development length:

(i) The calculated tension or compression in any bar at any section shall be developed on each side of the section by an appropriate development length or end anchorage or a combination thereof.

ϕ = Diameter of bar

τbd = Design bond stress = Permissible value of average bond stress

The value of bond stress is increased by 60% for a deformed bar in tension and a further increase of 25% is made for bars in compression.

In case of bundled bars in contact the development length is increased than that for individual bar by

1. 10% for two bars in contact
2. 20% for three bars in contact
3. 33% for four bars in content