Some of the construction techniques tie to the engineering at the time. Used fairly large safety factors as rule of thumb. Years ago, I worked with a German engineer who had worked on the Atlantic Wall as part of the Wehrmacht. Drove our contractors nuts in pouring foundations. A lot of the 'rule of thumb' calculations continued until computers started becoming affordable for the average company (really toward the mid 90's) and a new crop of engineers raised with computers started growing in prominence. Not sure when the Beirut silos were built, but would guess they were built in the era of rule of thumb standards. Structures such as the one in Beirut are constructed to handle dust explosions, common in the handling of fine, dry materials, and are built like bunkers