How to define effective depth of beams in ETABS

Effective depth of a beam is some thing that needs to be carefully understood while using any structural design software. This structural design parameter input is important since this effective depth of the beam decides the accurate steel needed to be provided in the beam.
By definition, effective depth is the distance measured from the most extreme compression fibre of the beam to the centre of gravity of the reinforcement group.
There are 3 structurally significant points to be carefully understood here
1. The compression and tension faces can differ across the length of a beam. Near the midspan compression is at top and near the support the tension is at top. So, the measurement of effective depth depends on the location of the section considered for design. You have to remember that the top and bottom rebar diameter can be different and hence the effective cover and there by the effective depth can also be different.
2. The second layer of reinforcement may be curtailed and hence the effective depth may differ across the length.
3. Also note that the same beam may be continuous and may have different effective depths as the number of rebars and diameter of rebar also can be different based on the moments in the beam spans.
All these points are explained in this structural blog video more carefully with sketches so that you will have a better understanding of this basic structural design question.
By the way this video is also a result of a question posted by one of our structural design students in the community. He is doing civilera ETABS course and was stuck up at this input of defining effective depth in ETABS.
I thought of explaining it a bit further and post a video that helps all of you to understand how ETABS can be used effectively for designing so that the reinforcement output is optimum. You can group beams with similar effective cover/effective depth and define same size in ETABS. For example, all beams with 2-T16 single layer and 2-T12 single layer of rebars can be grouped as same size. The difference in effective cover/effective depth of 4mm is not going to create a lot of difference in the structural design of the beam. So, you have to use your judgement and experience to correctly define this. Effectively grouping helps in design optimisation. Note that this step will be a re definition or re grouping after first iteration of design. In the beginning of the project, while defining you can use one effective cover as we have no idea about the forces at that time before structural analysis.
I have also written a blog on 7 rarely discussed points for beam structural design and you can read it in the link
Please ensure you read the structural blog too in addition to seeing this video as in the video, I have explained only about the effective depth but in the blog, you have many more simple points that we generally don’t even discuss.
If you have any questions about the points in the video or in the blog, please discuss it in our civilera structural forum www.civilera.com/forum

[@rabeeshkumar9664]

Nice Explanation👌

[@CIVILERABangalore]

Nice to know you liked it Rabeesh.

[@venkataranganadh7556]

Awesome sir👍

[@CIVILERABangalore]

Nice to know you liked it Ranganadh