design of rcc beam as per is 456

 

design of rcc beam as per is 456, tips for design of rcc beam, rcc beam design procedure

A RCC beam is Designed to maintain Safety in the structure and this design is followed by following flow chart.

Procedure of Design (As per IS 456-2000)

Calculating of Dimensions

·        Cross Section of Beam

1.Depth of Beam (D) = lc (clear length)/10                  (GENERALLY)

Or we can assume………..

2. Deflection criteria

                 7 ---> for cantilever

L_eff/d  =   20---> for simply supported                                        UP TO 10M

                26--->for continuous

                 7 X 10/l_eff ---> for cantilever

L_eff/d  =   20 X 10/l_eff ---> for simply supported                        AFTER 10M

                26 X 10/l_eff --->for continuous

 

Overall Depth (D) = d + Effective cover

Eff. Cover = clear cover + Փ (Stirrups) + Փ (main bar)/2

3. Effective span (Length)

  L_eff = L_c +W         or          L_eff =  L_c  + d                         which is Minmum

4. Loading Calculation

Dead Load:- Self weight => ٧_concretex b x D

Where:-  ٧_concrete= 25 kN/m³  (RCC)

                 ٧_concrete= 24 kN/m³ (PCC)

Live Load:- Given  (IS : 875 part-2)

Design Load (W_u) => 1.5 (D.L. +L.L.)

Design Moment (M_u) => W_u x L_eff²/8                    (for Simply supported Beam)

Ultimate resisting moment (M_ulimit)

               =  0.138 F_ckbd²  -------> Fe-250

M_ulimit      =  0.138 F_ckbd²   -------> Fe-415

              =  0.138 F_ckbd²   -------> Fe-500

Comparing moment if, M_u ≤ M_ulimit

Then beam is Designed as Under reinforced singly reinforced beam.

Else, cross section of the beam should be improve and beam is redesign as Singly reinforced beam. OR

Beam is Designed as doubly reinforced beam.