WHAT IS THE ESSENCE OF GENERATING MESH ON SLAB BEFORE ANALYSIS

If i model my project and add slab,what will be the difference if i dont generate plate mesh, after adding slab i add load and run analysis without generating mesh.

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  • If you do not mesh the slab, any load acting on the slab will bypass the beams and go directly into the column. So, the slab load will not induce any bending in the beams. That slab load will not induce any bending in the slab either. In the stiffness method, the pressure is converted to concentrated forces and concentrated moments at the 4 corners of the slab. For an unmeshed slab, the 4 corners coincide with the top nodes of the columns. So, the entire slab load goes directly as point forces and moments on the columns. 


    Regarding viewing the applied loads - see below:




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    I have seen many tread, where we can design a slab using " Floor load" also. My question is - " If we're designing a slab using "floor load" (without generating plate), how can we get the output of slab reinforcement details  in this case?, because in this case, all the stresses will transfer to the beam directly and further to the column through column and may lead to design of over reinforced beam.

    I have run an experiment analysis where I am getting higher reinforcement in beam (say beam no X) (when the structure is designed using Floor Load method instead of plate meshing under same loading condition) ?

    Which one method is more accurate Floor load or plate meshing to design ?

  • I would recommend meshing the slab together with the beams - through the common nodes they will act as monolith. Apply plate loads to the plates and the loading will be distributed to beams below, etc.. If you apply floor load - it will be applied to beams, not plates. Then design beams and plates as mentioned before.



  • I have designed slab using parametric model (By Generating Plate mesh) and compare results by applying 1)Plate pressure load 2) Floor Load. And I got the different results in both the case. Please help me to know, which approach is the realistic approach to design slab ?

    1) As,  I am getting max stresses in the middle portion of the slab under plate pressure loading condition and max stresses in the     middle edge beam under floor loading condition.

    P.S - While Applying Plate Pressure and Floor Pressure (Keeping load value and all other parameters same for comparison)

    Case 1 - Design Beam and Slab by applying Plate pressure load uniformly distributed over whole slab (In this case I am getting max stresses at the center of the plate)

    Case 2 - Design Beam and Slab by applying load of  Floor pressure (In this case I am getting max stresses at the middle beam).

    Case - 1  Beam Design with Plate Pressure Loading

    Beam Design with Plate Loading

    Case - 1  Plate Design with Plate Pressure Loading

    Case 2 - Beam Design with Floor Pressure Loading

    Case 2 - Plate Design with Floor Pressure Loading

  • The results for both approaches are as expected. To design the structure where the loads are distributed over the plate that is supported by beams - go with the plate load approach. If you are not designing the slab and it is only transferring the loads to beams - go with floor load (which will include the slab self weight too).
    Basically, the plate mesh generation is necessary to ensure the connectivity between other elements, proper load transfer, and generation of proper analysis results - deflections, moments, other.