Structural stability
All buildings
have to serve two important functions. They have to carry the loads (structural
requirement) and provide livable environment to the occupants to enable them to
be comfortable in the use of the building (functional requirement).
The building
has to carry its own weight and external occupancy loads and those caused by
the environment such as those caused due to wind or earthquake. The elements
that bear these loads and transmit them to the foundation are termed as “structural
elements”. A good performance of the structural elements such as beams and
columns is of vital importance from the safety and stability points of view.
Hence, they are designed and constructed with prescribed safety margins as per
requirements specified in the Bureau of Indian Standard specifications. Their
failure will cause cracking, yielding of steel and even ultimate collapse of
the building.
This type of
construction is undertaken in semi-urban and rural areas. All the main walls carry loads and also serve
to provide functional requirement. In these buildings, though the partition walls
do not carry structural loads, they cannot be either built or demolished
without due consideration for overall stability of the building. Some times
their weight may be required to provide stability against overturning failure.
The main walls invariably provide the structural stability and carry loads.
Hence, they cannot be damaged or dismantled for carrying conduits for
electricity, etc.
Bearing wall
buildings though safe for vertical loads are weak under lateral loads. They are
vulnerable for failure under out of plane bending during lateral loading.
Therefore, to make the building act as one integral unit, they should be
constructed with continuous plinth and continuous lintel beams. No brick pillar
should be less than 600 mm in width. All openings should be reinforced on all
sides. These simple precautions will ensure good performance of bearing wall
buildings under lateral loads caused by wind or earthquakes.
In many
sites the brick wall is first raised and then used as shuttering to cast the
column or beam adjoining it. This will make the column or beam weak because the
pores in brickwork will absorb the moisture from wet concrete making the w/c
ration in the beam and column uncertain. The weakness will manifest in the cover
concrete of the beam or column, leading to early onset of corrosion in the
rebars.
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