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 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

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.

Solution:

Aim:-

• Detailed design of beams from Etabs 2018.
• Provide details of longitudinal and shear reinforcements for the given two continuous beams.
• Calculate the maximum shear force value for one span of a continuous beam.

Introduction: -

• Beams are horizontal structural members used to support lateral loads.
• In conventional reinforced concrete structures, beams typically receive loads from floor slabs, but may also receive other loads such as wall loads, surfaces, and domestic equipment.
• RC beam design and detailing involves selecting the correct beam size and the amount of longitudinal and shear reinforcement to meet the requirements for final and serviceable conditions.
• After this, it is very important to place and position the beam reinforcements correctly on site to avoid construction errors.

Procedure: -

• Download the given attachment and open it.
• Check the load combinations.
• Run the analysis from the analyze tab or press f5.
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• 
• Now, start designing the beam by selecting the Start/Check Design option as shown below.
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• Once the check is finished with designing the beam, you need to select the “Show Design Info” option as shown below.
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• If you select the 'Show design information' option, a new tab will appear where you can select the longitudinal rebar in the design output and click the 'OK' button, as shown below.
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• Longitudinal reinforcement details are displayed as shown in the following image.
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• Next, we need to create a 3-span continuous beam reinforcement diagram along Grid-A and also specify the reinforcement details.
• Maximum branch of lower support is 1766mm² and lower center is 702mm²
• Maximum branch of upper support is 1889mm² and upper center is 4534 mm²
• Currently, we have 3-28Φ for top and bottom as shown below.
• Next, provide 1-8 Φ for the top support of the continuous beam as shown below.
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• Next, we need to draw a reinforcement diagram for the 7-span continuous beam along Grid-3 and also specify the reinforcement details.
• Maximum branch of lower support is 1061mm² and lower center is 1493 mm²
• Maximum branch of upper support is 1915mm² and upper center is 4794 mm²
• Currently, we have 3-22 Φ for top and bottom as shown below.
• Then provide 1-10 Φ and 1-12 Φ for the top support and 2-16 Φ bottom center for the continuous beam as shown below.
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• After specifying the beam reinforcement details, select the beam, and right click on the beam, a new tab will appear as shown below.
• Now you need to click on the Details option on the Concrete Beam Design tab as shown below.
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• Then the shear details are displayed below.
• According to section 6.3.3 the design force is 232 kn.
• Maximum Shear = 174.11kn
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Result:

• The beam was designed in detail by Etabs software.
• Specification for longitudinal and shear reinforcement of two continuous beams.
• In addition, the Etabs software was used to calculate the maximum shear force values ​​for continuous beams.