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    Types And Classifications Of Slabs | Sundayadoga

    Types And Classifications Of Slabs

    Slabs could be classified in various ways. The way you classify a slab, depends on the features you want to put into consideration.


    For instance, slabs could be classified based on the materials they are made of such as concrete slab, steel slab or composite slab.


     As the names suggest, concrete slabs are made of concrete (mixture of water, cement, fine aggregates and coarse aggregates), steel slabs are made of steel while composite slabs are made of combinations of various materials: e.g., steel and concrete.

    Slabs could also be classified based on the support type: e.g., simply supported slabs and continuous slabs.

    A continuous slab spans across more than two supports, whereas for a simply supported slab, there are supports at the two opposite edges only. In this case, no moment occurs at the edges and the critical section for design, is the midspan.

    For a restrained slab, the edges are held down firmly at the supports and develop hogging or negative moments. Here too, moment coefficients are given in the code for positive and negative moments.


    Consequently, slabs could be classified based on the geometry  e.g., circular slab. As the name implies, a circular slab is circular or round in nature.



    A flat slab has no beams at the supports all through the geometry of the slab. It is usually supported on columns which may or may not have column capitals. The columns themselves are connected to the drop panels of the slab to reduce punching shear.


    A flat plate is also a type of flat slab which usually has no drop panels. It rests directly on columns hence, serious punching shears develop at the supports, most especially when they carry enormous stresses. This makes flat plates unsuitable for large spans.


    A stair case slab is a special case of one – way slab. They are found mainly where there are stairs.


    The self-weight of the flight of steps in open-well and dog-leg stairs is calculated on the basis of slope length while imposed load is based on the plan length.

    The positive moment coefficients for these stairs are 0.10 for stair slab, either fixed or continuous, and 0.125 for one with no appreciable restraint.


    A hollow slab usually has opening within it.

    Other types of slabs include ribbed slab which has ribs running in one direction, usually along the span. It is also a special case of one-way slab.


    When the ribs run in both directions, forming dome-like structures, the slab type is a waffle slab. The forms for a waffle slab could be formed using steel pan forms, with timber falsework. A waffle slab is simply a two way ribbed slab.


    A solid slab is a very common type of slab. It normally has beams running across supports. The beams transfer the slab loads to the columns.


    Slabs could also be classified based on their locations or where they are used:

    A grade or ground slab usually forms part of the foundation on or within the ground, as is the case with a raft foundation.


    A floor slab is any slab used in the floor of a building. It forms the floor for any of the storeys of a building.


    A roof slab is any slab located at the roof of a building.


    These are the various types of slabs used in a building. Did I omit any that you know, then let me know in the comment section below.


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