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Sunday, 12 March 2017

Using AutoCAD to calculate load for from the slabs to the beams

       Slabs are the flexural members of a building or any structure supported by the beams or directly on the columns*. For the designing of the buildings, it is essential to calculate the loads that would be imposed on the beams due to the slabs.
This load is the dead-load of the slabs as in many cases the live load or the other associated loads are transferred using other methods. Currently, this post is regarding the dead load transfer only.

Load distribution methodology:

                The load from the slabs is distributed on the basis of the Yield Theory, the planes where the slab could possibly be deformed or cracked are considered to be the limiting zones of loading. Any slab is supported beams on either of its sides and their load is transferred to the beams in the following pattern.
Slab Type
Geometry Of Distribution
One Way
Rectangular Diving the Span Along the Midway
Two Way
Trapezoidal Diving the slab along the vertices with 45-degree inclination
The entire slab is supported by the beam

How can AutoCAD be useful for this Task?

Basically, the major share of the calculation is the estimation of the area from the geometry of the structure. Calculation of these areas could be tedious if done by hand. So whats’ the alternative?
1.       AutoCAD: Freely Available under student license for 3 years
2.       Planimeter: Costly and time-consuming.
On AutoCAD, you can just find the areas of those geometrical figures and then later by using excel convert them into their respective loadings.

Now How to implement the above on AutoCAD?

Watch this Video:###################################

Follow the steps:

1.       Using the polar tracking on with 45-degree project a line from the vertices to meet at the center for two way slab.
2.       After that complete the figure as per the instructions in the video.
3.       Then create a boundary in the figure simply press BO and then select the area to be bordered.
4.       Now that the boundary has been created the figure is covered by the polyline and the by using the list command LI the area and the perimeter can be observed.
5.       After having the areas you may use any mode of calculation but in my case, I prefer having Excel as it is extremely useful and saves the labour spent on repetitive tasks.

Hope you found this article useful…
Would appreciate your comment on this post!



  1. Its eassy to calculate load by using this method.😃

  2. Its eassy to calculate load by using this method.😃

  3. Theres an better way,by looking at the slab i.e one way/two way,you can know the load transfer of the slab to beam ( triangular,trapezoidal,rectangular).Knowing the load from slab,ie s.wt of slab,live load,floor finish and terming the total as W.You can derive the equivalent load on beam by converting triangular and trapezoidal loading to udl and then by derived equivalent load formulae we can find load of slab transferred on beam.Try it!

  4. Thanks for the info...
    There are a couple of methods, selecting the best suitable for your application..
    AutoCAD provides the area calculations with the best precision..

  5. Very informative....!
    Seems easy.