DESIGN STEPS OF RCC MEMBER FOR SHEAR AND TORSION

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Design of a reinforced concrete section for shear is carried on in the following steps:

(a)  Determine nominal shear stress of concrete by using following formula:

(b)  Determine design shear strength of concrete, (Table 1 below).

Table-1: Design Shear Strength of Concrete,  (N/mm²)

(c)  Provide shear reinforcements as per requirement and convenience. 

Fig: Shear failure in RCC Beams

Similarly, for design of a section for torsion one may proceed as given below :

(a)  Determine the equivalent shear force as below:

 

(b)  Calculate nominal shear stress, and if , only nominal shear reinforcement is to be provided. But if , both longitudinal and shear reinforcements are required.

(c)  Provide longitudinal reinforcement on tensile side for equivalent bending moment, M_e1= M_u + M_t where

If M_t> M_u, provide longitudinal reinforcement on flexural compression face such that the beam can also withstand an equivalent M_e2= (M_t – M_u), the moment Me2 being taken as acting in the opposite sense to the moment Mu.

(d) Provide two-legged closed hoops enclosing corner longitudinal bars of area A_sv, given by

But the total transverse reinforcement shall not be less than

For composite and integral behaviour of a reinforced concrete beam, the reinforcements are detailed in such a way that the stresses at every section are appropriately developed with the provision of appropriate amount and type of reinforcements. Proper cover to all reinforcements are also provided for durability and fire resistance.