18-09-2012, 11:26 AM
CBRI TECHNOLOGY
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PARTIALLY PRE-CAST R.C.C JOISTS
It is a square shaped Joist, 15 cm wide and the pre-cast portion is 15cm deep with stirrups
projecting out so the over all depth of the joist with in-situ concrete is 21 cm.It is designed
as composite Tee beam with 6cm flange comprising of 3cm pre-cast and 3 cm in-situ
concrete. This section can be adopted up to 4mt. span
STRUCTURAL DESIGN
The planks are designed as simply supported for self weight including in-situ
concrete in haunches and as continuous slab for live load and dead load of
floor finish and waterproofing treatment.
The joist is designed as simply supported tee-beam with 6 cm flange thickness.
Reinforcement is provided as per design requirements depending upon the
spacing and span of the joist.
The joist can be designed as continuous beam also for intermediate floors only.
For spans, more than 2.8 mt the joist at the support is to be designed as
doubly reinforced beam which necessitates welding of the bottom
reinforcement of adjacent joists at the support.
BALCONY CHAJJA PROJECTIONS
Balcony projections are provided along the partially pre-cast joists. The joist is designed
with an over hang carrying capacity for super imposed loads for balcony in addition to
the self load and the load due to railing. Main reinforcement is provided at the top in insitu
concrete, the pre-cast portion taking the compression. The free end of the joist is
propped adequately until in-situ concrete attains sufficient strength.