The testing of each wall consisted of the following steps:
1. Small air-pressure loads were applied to the specimen to
ensure a complete contact of the specimen with the two
upper and lower supports.
2. Once uniform support contact was achieved, the air pressure
was released and an initial reading was recorded.
3. Uniform increases in air pressure were applied in increments
of 2.4 kPa (50 lb/ft2).
4. At each loading increment, the wall specimen was visually
inspected for any distress and initiation of cracks.
Attention was also focused on monitoring the air bag for
any overinflated areas in which bubbles might form.
During the visual inspection, a relaxation in the air pressure
of the bag was noted that resulted in a drop off of the bag
load. This load drop was recovered during the subsequent load
increment.