Reinforcement Detailing of Beams from ETABS output

Aim:

Detail design of beams in Etabs 2018. The ETABS file for a G+4 building is provided. Run the analysis and design of the RCC Moment Resisting Frame. The following challenge deals specifically with two continuous beams on the 1st floor.

1) 3 span continuous beam along grid A

2) 7 span continuous beam along grid 3

Provide details of longitudinal and shear reinforcement for the two continuous beams. Sketch the beam elevation details or draft it using AutoCAD software.

Introduction :

*The design and construction of reinforced concrete buildings shall be governed by the provision of

IS 456:2000

* steel reinforcement of grade Fe 415 or less can be used

*strong steel is not preferable to low strength steel in earthquake-prone regions because the typical stress strain curve of low steel shows the following advantages a) long yield b) greater breaking strain c) less strength gain after the first yield.

Longitudinal Reinforcement:

*the top as well as the bottom reinforcement shall consist of at least two bars throughout the member length

*Analysis needs to be done

*Concrete design is done for this model

** 3 span continuous beam along grid A

At the top:

Maximum at end support 2046 mm^2

Minimum at end support 938 mm^2

Ast for 32 diameter = 804.24

Ast for 25 diameter = 490

Ast for 20 diameter 314

Ast for 16 diameter = 201

Ast for 12 diameter = 113

Maximum at the mid supports is 511 mm^2

** 2 bars of diameter 32mm and 1 bars of 25 r satisfies the overall Ast

2 x T32= 1608 mm ^2

T25 490 mm^2

2 X T32+ T25 = 2098 mm ^2

or

** 3 bar of diameter 32 mm satidfies the overall Ast

3 T32= 2412 mm ^2

At the bottom:

Maximum at the end support is 1945 mm ^2

Maximum at the mid support is 789 mm ^2

** 2 bars of diameter 32 mm and 1 bar of 25 mm satisfies the overall Ast

2 x T32= 1608 mm ^2

T25 490 mm^2

2 X T32+ T25 = 2098 mm ^2

or

**2 bars of diameter 32 mm and 1 bar of 20 mm satisfies the overall Ast

2 x T32=1608 mm ^2

T20 314 mm^2

2 X T32+ T20 = 1922 mm ^2

1)

2)

7 span continuous beam along grid 3

At the top:

**Maximum at end supports is 1940 mm ^2

**Maximum at Mid supports is 485 mm ^2

** 2 bars of diameter 32 mm and 1 bar of 25 m satisfies the overall Ast

2 x T32= 1608 mm ^2

T25 490 mm^2

2X T32+ T25 = 2098 mm ^2

At the bottom:

** Maximum at end supports is 1105 mm^2

** Maximum at mid supports is 1501 mm^2 ** 2 bars of diameter 32mm satisfies the overall Ast

2 X T32= 1608 mm ^2

Shear details

From etabs