Abstract:
primary school buildings are fabricated from unreinforced burnt clay brick masonry in
Khyber Pakhtunkhwa Pakistan. These school buildings are being targeted with improvised
explosive devices in the terrorist activities after 9/11 continuously. Consequently, several
hundred schools were partially damaged or fully collapsed due to improvised explosive devices
detonated in close vicinity. These school buildings are reconstructed again by the government
agencies without proper scientific knowledge of blast loading phenomenon and the expected
response of masonry buildings. Consequently, this research study is carried out to evaluate
response of brick masonry against blast loading.
In this report, response of burnt clay brick masonry against blast loading is investigated
experimentally. A representative primary school full scale unreinforced brick masonry building
and three different masonry systems (unreinforced, ferrocement overlay and confined masonry)
were fabricated in the field from typical burnt clay bricks with cement-sand (1:6) mortar
commonly used in Khyber Pakhtunkhwa Pakistan. All the four test specimens were placed on an
equal spacing on the perimeter of circle with a 3.66 m radius. The shock waves were generated at
the centre of the circle by igniting cylindrical shaped explosive charges placed at 0.91m height
from the ground surface. The test specimens were subjected to similar blast scenario in the eight
successive events with increasing explosive charge weights but fixed stand-off distances.
The recorded pressure data was processed and an empirical model predicting peak over
pressure for the cylindrical shaped explosives was developed. The damage level in test
specimens was evaluated after each successive blast event. Weak zones in masonry room were
identified and safe scaled distance for masonry room before collapse was experimentally
acquired. Scaled distances for different damage levels in the masonry system of walls were
obtained. The relative response of different masonry systems subjected to similar blast loading
environment was evaluated. The confined masonry, ferrocement overlay masonry and
unreinforced masonry walls were found in an increasing order of their responses against blast
loading.