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Earthquake :: Types of construction The types of construction usually adopted in buildings are as follows:
- Framed construction :- for multistoried and industrial buildings
- Box type construction :- for residential buildings
In FRAMED CONSTRUCTION people get the opinion of the experts of the various fields, Architects for the plan, Soil investigators for soil investigation, Structural Consultants for structural design and Civil Engineers for the proper implementation of the project.
But in BOX TYPE CONSTRUCTION generally people get the plan from the consultant and engage a contractor for the execution of the work. On the other hand if one gets the technical opinion of the expert, right from planning, selection of materials, structural design and Project Management, definitely the construction cost will be less without affecting stability and durability of the structure.
As per clause 8.4.1 of IS 4326 1993 all masonry buildings shall be strengthened by the methods, as specified for various categories of buildings as listed in the table below.
Strengthening arrangements recommended for masonry buildings (Rectangular masonry units.)
Strengthening arrangements recommended for masonry buildings (Rectangular masonry units.)
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Building
Category |
Number
of
Storeyes |
Strengthening
to
be Provided
in
all Storeys |
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| (1) |
(2) |
(3) |
| A |
i) 1 to 3
ii)
4 |
a
a,
b, c |
| B |
i) 1 to 3
ii)
4 |
a, b, c,
f, g
a,
b, c, d,
f, g |
| C |
i) 1 and 2
ii)
3 and 4 |
a, b, c,
f, g
a
to g |
| D |
i) 1 and 2
ii)
3 and 4 |
a to g
a
to h |
| E |
1 to 3* |
a to h |
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where
a - Masonry mortar
b - Lintel band
c - Roof band and gable band where necessary
d - Vertical steel at corners and junctions
of walls
e - Vertical steel at jams of doors, windows and openings
f - Bracing in plan at tie level of roofs
g - Plinth band where necessary
h - Dowel bars
*4th
storey not allowed in category E
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Note: In case of four storey building of category B, the requirements of vertical steel may be checked through a seismic analysis using a design seismic coefficient equal to four times the one given in (a) 3.4.2.3 of IS 1893 : 1984. (This is because the brittle behavior of masonry in the absence of a vertical steel results in much higher effective seismic force than
that envisaged in the seismic coefficient, provided in the code). If this analysis shows that vertical steel is not required the designer may take the decision accordingly..
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From the table above it can be noticed that the strengthening arrangements depends on the category of the buildings. The buildings have been categorized in 5 categories A to E based on the value of ah given by:
ah
= a0 I.ß,
where
ah = design seismic coefficients for the building
a0 = basic seismic coefficient for the seismic zone in which the building is located
I = importance factor applicable to the building
ß = soil foundation factor
From the above, the measures to be adopted also depends on 'I' the important factor of the building.
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| In my opinion each and every house is important for the owner irrespective of the size. So one should take all the precautions as envisaged in the IS 4326; 1993 during the construction.
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