This document discusses blast resistant structures and provides information on: - The need for blast resistant structures due to increasing terrorist attacks to minimize damage, loss of life, and social panic. - Types of blasts include moving vehicle attacks, stationary vehicle bombs, exterior attacks, arsons, and ballistic attacks. - Principles of blast resistant design include maintaining stand-off zones, sustaining bomb damage without progressive collapse, and minimizing broken glass and debris. - Effects of blasts on structures include conversion of energy to thermal radiation and shock waves that expand radially.

1. BLAST RESISTANT
STRUCTURES
Submitted by,
S.ARUNRAJ
M.E. STRUCTURAL
ENGINEERING,
ANNA UNIVERSITY
REGIONAL CAMPUS,
MADURAI.

2. Agenda:
Need
Types of blasts
Principles
Effects on the structure
Preventive measures:
(i) Measures to be taken while planning
(ii) Measures to be taken while construction
Installations
Bomb shelter areas
conclusion

3. Need:
Increase in number of terrorist attacks.
To minimize damage to the assets
To minimize the loss of life.
To protect historical monuments and important buildings
To subside social panic

4. Moving
vehicle
attack
Stationary
vehicle
bomb
Exterior
attack
Arsons
Others
Ballistic
attacks

5.  Maintain safe separation of attackers and targets i.e. STAND-
OFF zones.
 Design to sustain and contain certain amount of bomb damage.
Avoid progressive collapse of the building.
 Allow for limited localized damage of members
 Minimize the quantity and hazard of broken glass and blast
induced debris.
 Facilitate rescue and recovery operation with
adequate time of evacuation of occupants.
Principles Of Blast Resistant Design:

6. Effects of blast on the structure:
An explosion is a rapid release of potential energy
characterized by eruption enormous energy to the
atmosphere.
A part of energy is converted to thermal energy radiation(flash)
and a part is coupled as air blast and shock waves which expand
radially

7. How to safeguard the structure
from these effects

9. Planning and layout:
 Sufficient stand-off distance
must be provided.
 In case of congested areas
where there is no provision
for stand off distance,
bollards, trees or street
furniture are to be provided
as obstacles.

11. Structural Solutions for Blast Resistant Buildings:
Roof: Arches and domes are the types
of structural forms that reduce the
blast effects on the building compared
with a cubicle form.
Flooring: They must be prevented
from ‘falling off' their supports. Pre-
cast flooring is to be avoided in case
of blast resistant structures

12. Beam-to-column connections:
Frame structures are deficient in
2 aspects:
 failure of beam to
column connections
 Inability of the structure
to tolerate load reversal
 providing additional
robustness to these
connections can be
significant enhancement. Side plate connection for a steel
structure

13. Beam to column connection in Reinforced
concrete structure

14.  The use of extra links and the location of the starter bars in the
connection reduce the collapse and damages.
 In critical areas full moment-resisting connections are
made in order to ensure the load carrying capacity of
structural members after an explosion

15.  The need for fire resistance, strength and ductility favors
reinforced concrete as a construction material for floors.
Blast-resistant design philosophy allows structural
elements to undergo large inelastic (plastic) deformations in
response to blast loading.
• A ductile structure that undergoes large deformations
without failure can absorb much more energy than a brittle
structure of the same static strength
Ductile Detailing Of Reinforcements:

17.  Tensile reinforcement between 0.5 and 2 percent of the cross-
sectional area of the concrete element will usually insure
ductile behavior while providing the required strength.
 Compression steel in flexural members serves two purposes.
After a structural member is deflected by blast loads, it
attempts to spring back or rebound. Dynamic rebound causes
load reversal and, under certain circumstances, can result in
catastrophic failure

18. Wrapping of columns:
Wrapping is done to done for
external protection of columns
and also to protect the column
from shock waves. Two types
ofwrapping can be applied.
Wrapping with steel belts or
wrapping with carbon fiber-
reinforced polymers (CFRP).

19. Miscellaneous measures:
 Partially or fully embed buildings are quite blast resistant.
 Projected roofs and floors are undesirable
 Single story buildings are more blast resistant than multi story
buildings
 Double-Dooring should be used.

20. Installations:
Gas, water, steam installations, electrical connections,
elevators and water storage systems should be planned to
resist any explosion affects.
Bomb shelter areas:
The bomb shelter areas are specially designated within the
building where vulnerability from the effects of the explosion
is at a minimum and where personnel can retire in the event
of a bomb threat warning.

21. Glazing and cladding:
Glass from broken and shattered windows could be responsible for
a large number of injuries caused by an explosion in a city centre.
The choice of a safer glazing material is critical and it has been
found out that laminated glass is the most effective in this context.

22. Conclusion:
 It is not practical to design buildings to withstand any
conceivable terrorist attack.
 It is possible to improve the performance of structures
should one occurs in the form of an external explosion
 Design process to ensure that appropriate threat
conditions and levels of protection are being
incorporated.

23. Thank
you