Reinforcement Detailing of Beams from ETABS output
Detail design of beams in Etabs 2018.
The ETABS file for a G+4 building is provided. Run the analysis and design the RCC Moment ResistingFrame. The following challenge deals specifically with two continuous beams in the 1st floor.
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.
• Provide reasons for failure of the middle span along grid A. What are the possible ways this issue can be resolved?
• Calculate value of the maximum shear force in any one of the spans in both the continuous beams, as per clause 6.3.3 (b) in IS 13920 – 2016. Also, confirm these values from shear force demand calculated by ETABS.Please note that if longitudinal reinforcement provided is more than required (as per ETABS results), the shear force demand will vary from what is provided by ETABS.
Procedure:-
- Open the file in Etabs.
- Check the model and run the analysis.
- Click on concrete frame design as shown in figure.
- Now click on display design info.
- Select longitudinal reinforcement.
- Reinforcement diagram.
- Along the Grid A
- At the top:
- Maximum at end support 2046mm^2
- Minimum at end support 938mm^2
- Maximum at the mid support is 511mm^2
So, providing 2 bars of dia 32mm and 1 bar of 25mm satisfies the overall Ast.
- At the bottom:
- Maximum at the end support is 1945mm^2
- Maximum at the mid support is 789mm^2
So, providing 2 bars of dia 32mm and 1 bar of 25mm satisfies the overall Ast.
As per clause 6.3.3.3 provide the 3 legged stirrups of dia 10mm with spacing 95mm along the entire length of the beam.
ii.Along the Grid 3
- At the top:
- Maximum at end supports is 1940mm^2
- Maximum at mid supports is 1501mm^2
2 bars of dia 32mm and 1 bar of 25mm satisfies the overall Ast.
- At the bottom:
- Maximum at end supports is 1105mm^2
- Maximum at mid supports is 1501mm^2
2 bars of dia 32mm satisfies the overall Ast.
As per clause 6.3.3.3 provide the 3 legged stirrups of dia 8mm with spacing 100mm along the both ends of the beam and 3 legged stirrups of dia 8mm with spacing 150mm at mid span.
