Reinforcement Detailing of Beams from ETABS output
Reinforcement Detailing of Beams from ETABS output
Challenge 7 – Detailed design of concrete buildings -1
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.
1.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:
2.Provide reasons for failure of the middle span along grid A. What are the possible ways this issue can be resolved?
3.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.
AIM : To design the continuous beam by using the ETABS software.
Procedure:
Open the attachment first then download the file and then open the file till will open in the ETAB software.
Now we have to click on run analysis then we have to click on concrete frame design.
Now the design will completed
It showing the longitudinal reinforcement
Now the share reinforcement go to the concrete frame design in that drop down we have the display info change it to logitudinal to shear and then click on aplly then the shear reinforcement will display
1.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:
7 span continuous beam along grid 3 Longitudinal reinforcement of beam at grid 3 from ETABS (mm^2)
7 span continuous beam along grid 3 Shear Reinforcement of beam at grid 3 from ETABS (cm^2/1000mm)
3 span continuous beam along grid 3 Longitudinal reinforcement of beam at grid 3 from ETABS (mm^2)
3 span continuous beam along grid 3 Shear Reinforcement of beam at grid 3 from ETABS (cm^2/1000mm)
Now we have to draw the reinforcement details in the auto cadd software
First we have to calculate the rebars Ast for beam top and bottom section
7 span continuous beam along grid 3 Longitudinal reinforcement of beam at grid 3 from ETABS (mm^2)
In this we have calculated the top bars are 3 bars of 25ϕ and one bars of 20ϕ bottom 2 bars of 25ϕ
The maximum Ast for the bottom support is 1061mm^2 and bottom middle is 1493 mm^2
The maximum Ast for the top support is 1915mm^2 and top middle is 479mm^2
Next we provide 1-10ϕ and 1-12ϕ at the top supports and we provide 2-16ϕ at the bottom middle for the continuous beam, as shown below
Next we need to draw the Reinforcement diagram of 3 span continous beam along Grid-A, and also need to provide the reinforcement details.
The maximum Ast for the bottom support is 1766mm^2 and bottom middle is 702mm^2
The maximum Ast for the top support is 1889mm^2 and top middle is 453mm^2
Now we provide 2-32ϕ at the top and bottom, as shown in the below figure.
Next we provide 1-20ϕ at the top supports for the continuous beam, as shown below.
After providing the beam reinforcement details, we select the beam and right click on the beam then the new window popup
Next we need to click on the Details option in Concrete beam design tab
The details will shown as below :
2.Provide reasons for failure of the middle span along grid A. What are the possible ways this issue can be resolved?
The span along the grid a is failed in over stressed because the stress is increased behond the allowble value
That the reason it is difficult to calculate the shear reinforcecment
The possible ways this issue can be resolved is reduce the load acting on the beam or increse the area of the beam
Another way that increase the shear strength in the concrete by using high gread concrete.
We can see that in result details
3.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.
Clause 6.3.3 (b) in IS 13920 – 2016
Sway shear force to Right :
Mas = 174 kNm
Mbh = 293 kNm
Lab=4.725 m
V.d+l = 92 kN
After substituting the values we get,
V u,a= 46 kN
V u,b = 230 kN
Sway shear force to left :
Mah = 234 kNm
Mbs = 155 kNm
Lab=4.725 m
V.d+l = 70 kN
After substituting the values we get,
V u,a= 185 kN
V u,b = 45 kN
Result :
The details of longitudinal and shear reinforcement for the two continuous beams is Provided. The beam elevation details Sketched or drafted it using autocad software.
Reasons and the possible ways this issue can be resolving of failure of the middle span along grid A id provided
The 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, confirmed these values from shear force demand calculated by ETABS.