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.
• 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?

• 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.

Answer -

Aim - to design the beams in details from Etabs.

To provide details of longitudinal and shear reinforcement for the given two continuos beam.

To calculate the value of maximum shear force in any one of the spans in the continuous beam.

Introduction -

Beams are the horizontal structural elements ussed for the supporting lateral loads.

In conventional reinforced concrete structures, beams usually recive load from the floor slab, but may also subjected to the other loads such as

wall loads, finishes, Service installation etc.

It is very importnat that the beam reinforcements are placed and arranged properly on site, to avoid construction error.

Procedure -

Step 1.

First we have to open the challenge 7 page and download the challenge.

After the downloading the challenge open it in etabs.

Step 2.

Next we have to check the load combinations.

Step 3.

Next we have to start the beam design by selecting the Start design check option.

Step 4.

After the complition of the beam design, We need to select the Display Design info option.

After selecting the Display design info option the new tab appears, in that we select the Longitudinal reinforcing in the design output and click

on the ok button.

Next the longitudinal Reinforcement details will appears.

Step 5.

Next we need to draw the reinforcement diagram of 3 span continuous beam along Grid A and also need to provide the reinforcement details.

The maximum Ast for the bottom support is 1766 mm^2 and bottom middle is 702 mm^2.

The maximum Ast for the Top support is 1889 mm^2 and top middle is 453 mm^2.

Now we provide 3-28Φ at the top and bottom.

Next we provide 1-8Φ at the top supports for the continuous beam.

Step 6.

Next we need to draw the reinforcement diagram of 7 span continuous beam along Grid 3 and also need to provide the reinforcement details.

The maximum Ast for the bottom support is 1915 mm^2 and bottom middle is 497 mm^2.

The maximum Ast for the Top support is 1889 mm^2 and top middle is 453 mm^2.

Now we provide 3-22Φ at the top and bottom.

Next we provide 1-10Φ and 1-12Φ at the top supports and we have to provide 2-16Φ at the bottom middle for the continuous beam.

Step 7.

After providing the beam reinforcement details, we select the beam and right click on the beam then the new tab appears.

Next we need to click on the Details option in concret beam design tab.

Next the shear details will be visible.

As per the clause 6.3.3. the design force is 232kn.

We got maximum shear force = 158.32 kn/m