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PERFORMANCE
Performance under Vertical Loads
The
precast wall panels are designed as load bearing wall system. Depending
on the height of the building, the thickness of the wall panels can
be varied. The wall is reinforced with BRC mesh at the center both
for the vertical load support as well as during the lifting/installation
stage. The wall is stiffened with enlargement to 200mm thick at the
edges and reinforced using high tensile reinforcement. These top stiffened
edges act as transfer beams for window or door openings while the
side stiffened edges allow stronger support during lifting stage.
Integrity or Strength of Joints
The thickening of the edge of the wall panel allows
for a reasonable size of vertical recess to be formed on either side
of the wall panel to form a core for the construction joint of 125
x 100 oval shape cavity when two adjoining panels or panel and column
are assembled together and this provides a space of tolerance for
easy installation. This large cavity can be filled with chipping concrete
well vibrated to form a strong wet joint. This wet joint also acts
as a cast-in-situ stiffener (once a vertical steel bar has been inserted
and concrete has been poured into the core) and bonds the panel to
the column. As such, it can prevent the ingress of water effectively.
This joint is able to transfer lateral load by shear action of the
concrete infill to the adjacent columns. This can be further improved
by adding non-shrinkage cement-plaster to finish the construction
joint of all external walls. For horizontal construction joints, rawl
bolts are inserted into the floor beam for levelling control prior
to pouring the expandite concrete and installation of the precast
concrete wall panel. Two groove lines along the bottom face of the
panel will provide better bonding and also prevents ingress of water
effectively. (Refer to Illustration - 2 I Fig. 2.07).
Performance under Lateral Loads
The
lateral loads are transferred from the wall panels to the adjacent
columns via shear key action in the concrete infill between the panel
and column. These lateral loads are then resisted by the cast-in-situ
columns, which are adequately reinforced.
Durability and Design Life
As the system consists of cast-in-situ columns, precast concrete wall
panels and half-slab floor panels that are finished with in-situ topping
and BRC, the durability is essentially governed by performance of
concrete. With the Grade 35 concrete used, the panels are very durable
and the design life will exceed the 50 years required by the code
of practice.
Fire Safety and Toxicity
The grade 35 concrete precast panels provide very good fire resistance.
The concrete is non-combustible material and hence does not give out
any toxic gas
Environmentally Friendly
The construction site is practically free of messy clutter and debris
while being more environmentally friendly at the same time. |
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