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Worksite Safety 1
Dr. K.N.Jha
Department of Civil Engineering
Indian Institute of Technology Delhi
Block V
Room No. 322
Safety of temporary structures
•Why ‘Temporary structures’ do not deserve ‘temporary’
treatment?
•How accidents are caused due to failure of temporary
structures?
•
Contents2
• ‘Temporary’ gives a feeling as if it is
something not that important
• But is it the case-
• In RCC Construction, Temporary structures say
formwork• Quality, Economy, Safety
• Consumes about 40-50% of the total cost and about 60-70%
of the time
• Major investment required
Why ‘Temporary Structures’ do not deserve
‘temporary’ treatment?3
Thus ‘TEMPORARY’ is really not ‘Temporary’
Common defects due to poor formwork quality
1. Honey comb
Formwork needs to be designed & built accurately so that the desired size, shape position, correct location, quality and finish of acceptable quality of
the cast concrete are attained.
Quality
Common defects due to poor formwork quality
2. Poor Construction Joint /Offsets in Concrete Joint
Quality
Common defects due to poor formwork quality
3. Plywood Grains Stuck on the Concrete Surface
Quality
In Building Construction
60% Failure due to Formwork Collapse, Shoring
Collapse, Inadequate Shoring & Lateral Bracing
8% due to premature removal of shore.
18% Failure is due to faulty materials.
Thus Formwork needs to be built adequately so that it is capable of
supporting all dead & live loads without danger to workmen and to the
concrete surface.
Safety7
How accidents are caused due to failure of temporary
structures?8
Collapse of
one floor
leading to
another
View of
collapsed
waffle slab
segment
9
Another view
of collapsed
waffle slab
segment
10
View of the
bent shoring
(due to excess
load)
11
Collapse of
deck slab
between the
two piers
12
Another view
of the
accident site
13
Shoring tower
in position for
the deck slab
adjacent to
the collapsed
slab
14
View of the
portion of the
slab which
failed due to
concrete
overloading
15
Another view
of the portion
of the slab
which failed
due to
concrete
overloading
(note the
buckled
props)
16
Another view
of the portion
of the slab
which failed
due to
concrete
overloading
17
View of
portion of
slab and
beam
formwork
which
collapsed
18
Another view
of portion of
slab and
beam
formwork
which
collapsed
19
Failure of Launching Girder20
Collapse of
launching
girder in
Laxmi Nagar
Collapse of under construction metro bridge21
View of
Zamrudpur
under
construction
metro bridge
span collapse
Bridge failure during construction22
view of the
accident site
(photo
courtesy
www.chinapos
t.com.tw)
Bridge failure during construction23
Another view
of the
accident site
(photo
courtesy
www.thehindu
businessline.co
m)
Fall of Girder during construction24
View of
dislocated
shutters
Fall of Girder during construction25
Toppled
Girder lying
on ground
Economy
Corresponds to profitable, careful, efficient and
prudent use of resources for making of the forms.
Formwork cost = Cost of form materials + cost of labor for
making + cost of labor for fixing & removing + cost of
equipment required to handle the form + cost of consumables.
Formwork may cost up to 60% of the total cost of concrete work.
Economy26
Heavy investment required to be made in formwork system.
A formwork system once chosen continues to be in use by the organization for long periods. This calls for all the more reasons to select the formwork system carefully.
Traditionally formwork required skilled tradesmen which are in short supply in modern days.
The speed of RCC construction is largely governed by the quantity of formwork materials mobilized.
Other reasons -why formwork is important?
