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. A sample of how beam elevation details is prepared in consultancy firms is provided below. Participants can prepare it as per their preference:
• Provide reasons for failure of the middle span along grid A. What are the possible ways this issue can be resolved?
A)
AIM;
We need to analysis the given model and we need to exctract the given model and detailing of 2 mentioned RC beams and also we need to recheck the gride A Rc beam.
Design of RC beam ;
1)we need to check the given etabs model
2)And we need to do Run Analysis.
3)we need to check whether there is any errors and warnings then only we need to go to furter step.
4)Now go to the desing in that go to frame design prefernece and assign the loads to given model.
5)In design goto the design combinations and do the check so that we ensure the design codeassignment and load combinations.
6)goto the design and verify the all members passed or not
7)in that go to the flexture reinforcement and shear reinforcement and design the cretria of the Rc STRUCTURE.
8)As per the drawing given frome the code book we can ensure some points about the Gride A RC beam.
As per the above shear force value we got 3.58 MPa compare to the maximum allowable shear stress is 3.97 MPa is tells us that it is failing by it . This can be resolved in any of the following process;
a) Optimizing provided flexural reinforcement of the beam.
b) increasing concrete grade will increase allowable shear stress limit.
• 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.
a)
gride-A RC Beam
Support top flexural reinforcement as per Drawing =132 sq.mm
Support bottom flexural reinforcement as per Drawing = 154sq.mm
Using Annexure-G of IS-456 indian standard, the moment capacity of RC beams are calculated as follow.
demand shear force from ETABS analysis 23.4KN
Clear span=2.65m
Using clause 6.3.30 of IS13920-2016 indian standard, the sway shear force is calculated as follow.
1. Sway shear at Left as per IS 13920-2016 = 453.19 KN
2. Sway shear at Right as per IS 13920-2016=435.09 KN
Required shear reinforcement as per calculation = 2234 sq.mm
Provided shear reinforcement as per drawing = 3920 sq.mm.
Grid-3 RC beam:
Support top flexural reinforcement as per Drawing =129 sq.mm
Support bottom flexural reinforcement as per Drawing = 143 sq.mm
Using Annexure-G of IS-456 indian standard, the moment capacity of RC beams are calculated as follow.
demand shear force from ETABS analysis 165KN
Clear span=3.65m
Using clause 6.3.30 of IS13920-2016 indian standard, the sway shear force is calculated as follow.
1. Sway shear at Left as per IS 13920-2016 = 345.34 KN
2. Sway shear at Right as per IS 13920-2016=349.56 KN
Required shear reinforcement as per calculation = 1478 sq.mm
Provided shear reinforcement as per drawing = 1256 sq.mm.
Conclusion ;
designed the etabs model as per the given fesications and by using the ductility standards.