Hardened structures are designed to withstand any heavy loading which may be encountered due to hurricanes, tornadoes & other severe weather events; and blasts from bombs, explosions, artillery and nuclear explosions. The masonry system described on this blog can provide hardened structures in a number of design layouts at a reasonable cost, while providing a high safety factor.
Most of us are aware of the backyard bomb shelters which were fairly common at the height of the cold war. These were typically underground structures designed to withstand a nuclear war, and would allow a family to survive the immediate blast and fallout period following a nuclear attack.
Surprisingly, there is still a large market for hardened structures which offer to help people survive such ominous threats as discussed in this article from Popular Mechanics: “The bomb shelter business is booming. At least that's the consensus of the men and women who design, construct and install underground sanctuaries. They attribute the growth in business to Kim Jong Il's erratic missile lobbing, the intransigent Iranian clerics hell-bent on getting nuclear weaponry, the impending total collapse of the global financial system, and the end of the world in 2012, as predicted by the Mayan Calendar.
"For whatever reason—and we're not totally sure ourselves—but business is incredible," Brian V. Camden, an engineer at high-end shelter builder Hardened Stuctures, says. "Twenty-twelve, the financial collapse: I just had to hire a new architect Tuesday. Right now we're doing a lot in Tennessee, Kentucky, Pennsylvania. All through Appalachia, it's people who share a similar mind-set."
The market for hardened structures is met by companies like Hardened structures of Colorado. This market segment seems to be populated by nice people. If you read their marketing material you get the feel for it.
Kim Jong Il and the Mayan calendar notwithstanding, a very real need for hardened structures is to have a safe room for tornadoes in the section of America known as “tornado alley.” Another real need for hardened structures is for any area prone to hurricanes. In an average year, 800 tornadoes are reported nationwide, resulting in 80 deaths and over 1,500 injuries. Landfalling hurricanes cause around 20 deaths per year, and around $5.2 billion in damage, according to NOAA.
The masonry system I’ve been describing can provide a high performance, economical method for building a hardened structure. A hardened structure using this design should ideally utilize the “dimp” design; it should also employ a tensile web woven into the block, and its performance is further increased by building concentric shells, one over the other, in an onion skin-like arrangement. Such a structure would be toughened (resistant to crack propagation), hardened, strengthened, robust (insensitive) and secure.
Blast-resistant structures for military and defensive applications have a unique set of parameters that they must address. This is pretty interesting stuff, and we’ll take a look at that next time.
Armageddon? I’m-a-gettin’ out of here!