HIDDEN BEAM
What is hidden beam?
·
Hidden Beam, also known as Concealed
Beam, is defined as the beam whose depth is equal to the thickness of the slab.
·
The concept of the hidden or concealed
beam originated from flat slab concept.
·
Hidden beam is a means to describe the
dispersion on the supporting slab.
·
The hidden beams are only means to
spread the concentrated load of the wall on the slab area.
·
The hidden is virtual bean designed to
make use of the beam free room head.
·
By providing hidden beam floor height
can be achieved.
·
Concealed beam clears way for
electromechanical duct work.
·
It allows using greater span for the
slab.
·
Concealed beams are economical and
have aesthetic appearance of the building.
Where Hidden/ Concealed Beams are used?
·
Hidden / concealed beams are provided
in between living and dining space right angle to each other. This gives a neat
and level ceiling surface that provides a good appearance.
·
Hidden beams are generally inserted
within the suspended slabs where slab thickness is considerable.
·
Hidden beams also provided between
balcony and room to facilitate easy inclusion of balcony into room space.
·
Hidden beams are provided mostly for
architectural aesthetic requirements for building interiors.
·
Many Structural engineers provide
these hidden beams under partition walls.
Design of Hidden/ Concealed Beam:
·
Hidden beams are reinforced separately
from the slab, having stripped and longitudinal bars just as normal beam but
its death is limited, should not be greater than the slab thickness. The depth
of the beam is limit to the slab depth say 4.5” to 5”, and the width vary from
1’ to 4’, based on the load coming from the slab load including self weight,
floor finish, live load and partition wall weight. The bending moment shall be
calculated as wl2/10.
·
The reinforcement shall normally be
provided at bottom and top equally from practical consideration. Some designer
may designed the beam using steel beam theory. The width is so selected that
the beam should satisfy max shear stress consideration. Based on shear to be
designed, the stirrups shall be provided and the spacing is limit to maximum
depth of the slab.
·
It saves floor height concrete.
·
It gives best aesthetic interior appearance by
providing greater headroom clearance.
·
It is economical as it saves the cost of
materials, formwork and labor.
·
It clears the way for horizontal
electromechanical ductwork.
·
It is easier to apply a finish to the
underside of the slab, often saving the time in construction process.
Disadvantages of Hidden/ Concealed Beam:
·
Structurally hidden beams create a spanning
problem, as spans for structural supports are at right angle to each other.
This means one slab structurally rests over the other.
Hidden or
Concealed beams are mostly used in Solid Slab, Ribbed Slab or Hollow Core Slab
and Waffle Slab.
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