Reinforcement Detailing of Beams from ETABS output

AIM-

To carryout design of RCC model in etabs .

-Design in here  rcc moment resisting frame .

-provided rcc reinforcement in longitudinal 

and shear in 2 beams 

-give reason of failure of middle span along 

grid A .

INTRODUCTION -

IN THIS CH. 2 BEAM DETAILING IS DONE.

   1) 3 span continuous beam along grid A
        2) 7 span continuous beam along grid 3

Address the following issues thereafter.
        • Provide details of longitudinal and

shear reinforcement for the two continuous beams.

Sketch the beam elevation details or draft it using

autocad software. A sample of how beam elevation

details is prepared in consultancy firms is provided below.

-IN order to calculate maximum shear force in any of 

span of continious beam.

-IS 13920- 2016, Clause 6.3.3  b 

is followed which state that 

-shear force capacity of beam  larger than 

a] factored shear force as per linear structural 

analysis .

-b]factored gravity shear force plus  equilibirium shear force  ehn plastic hinges are formed at both the ends of beam given by 

1.For sway to right :

2. For sway to left:

.PROCEDURE -

-intially open  etabs .

-go to analysis > check model .

-

-After that go to analysis and analysis  model  

by run analysis option .

-after complete analysis  go to  concerete  frame

  design , drop down and carry out  design of 

beam by chossing start design  check  option .

-after completion  , reinfocement values are 

obtain for display ,design info option in concerete 

frame design option .

-now we need to carryout detailing of grid  A 

and grid  3 continious beam .

-intially  detailing is done for  grid  A 

-maximum values of reinforcement AT top 

is 2045 mm2 and at the bottom  1945  mm^2

-hense provide  2 no. of 32mm dia. at top and 

bottom i.e 1608mm^2

-then ,we will provided  25 mm dia. bar to 

satisfy remaing .

-cover provided is 30mm .

-shear reinforcement at 10mm bars @50mm c/c 

throughout then beam .

-now detailing is carried out for grid 3 

-maximum values of reinforcement at 

top 1940 mm2 and at and bottom is 1501 mm^2 .

-hence provided 2no. of 32 mm dia bars to

satisfy remaing [only at top ].

-cover provided 30mm .

-shear reinforcement provided as 10mm

dia bars @100mm c/c through out of beam. 

-

-

beam detailing is complete .

-possible  reason for failure of middle span 

along grid  A .

failure due to higher shear stress , shear stress devloped

is 3.11 mpa  > allowable shear stress 3.1 mpa which leads to failure of this beam .

possible ways to solved at that type issues .

-using higher grade of concerete  which increase permissible stress in it .

-shear strenghth of beam can be increased  by redusing effective depth  of beam .

now for grid  A sway left to right 

HOGGING MOM. AND SAGGING MOM. RESISTANCE  173.97 KNM , 292.99 KNM .

Factored shear force due to vertical load acting on span .

,V_u,b^D+L=114.9754kN

Clear span, 

L_AB= 4.725m

So as per IS13920 sway shear is calculated as:

V_u,b= 253.32kN for sway to right

Now, for sway to left the sway shear is calculated as:

V_u,b= 252.43kN for sway to left.

Shear force demand calculated by etabs : 237.54 kN 

Take the shear sway to be 253 kN.

 Grid 3:

Sway to right 

Hogging moment of resistance = 161.07 kN m

Sagging moment of resistance = 219.39 kN m 

Factored shear force due to vertical loads acting on the span ,V_u,b^D+L= 88.23 kN

Clear span, 

L_AB= 3.95 m

So as per IS13920 sway shear is calculated as:

V_u,b= 240.4 kN for sway to right

Now, for sway to left the sway shear is calculated as:

V_u,b= 243.386 kN for sway to left.

Shear force demand calculated by etabs : 209.552kN

Hence take the shear sway as 240 kN. 

Result :

Hence, the entire detailing and designing of beam is completed.

-