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.

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