The Steel Reinforced Concrete Dome is the most disaster resistant building that can be built at a reasonable price without going underground or into a mountain.
A wind of 70 miles per hour blowing against a 30 foot tall flat walled building in open flat terrain will exert a pressure of 22 pounds per square foot. If the wind speed is increased to 300 miles per hour the pressure is increased to 404 pounds per square foot (psf). Wind speed of 300 mph is considered the maximum for a tornado. It is far greater than that of a hurricane.
DOMES WITHSTAND TREMENDOUS PRESSURES:
Cars can be parked on 100psf. The side pressure on the building could equal the weight of cars piled 4 high. No normal building can withstand that much pressure. Many Steel Reinforced Concrete Domes are buried up to 30 feet deep. They must withstand pressures up to 1 ton per square feet (2000 psf).
Against tornado pressure a Steel Reinforced Concrete Dome 100 feet in Diameter, 35 feet tall would still have a safety margin of 1. ½ times its minimum strength. In other words, the stress created by the 300 mile per hour wind would increase the compressive pressure in the shell to 1,098 psi. The shell is allowed 2,394 psi using design strengths of 4,000 psi. The fact is the Steel Reinforced Concrete Dome is not flat and therefore never could the maximum air pressure against it of 404 pounds per square foot be realized. Neither is the concrete only 4,000 psi. It is always much greater. The margin of safety is probably more like three or four.
The Steel Reinforced Concrete Dome at Port Arthur, Texas has now been hit by three hurricanes. A hurricane does not exert enough pressure on a dome to be even noticed. As shown above the dome can very easily withstand the stresses of a tornado.
However, debris carried by a tornado could cut the surface membrane. If the debris contained a large timber or metal object, it might be possible of conditions were just right to put a puncture into the dome. But the puncture would be very local and would certainly never cause serious collapse of the dome. Possibly damage to the doors or windows may occur if there was a rapid decompression caused by the tornado.
For most Steel Reinforced Concrete Domes the likely disaster will be earthquake. The worst areas in the United States are listed as seismic zone 4. From analysis (see “concrete dome wind analysis” sidebar) it is easy to see that earthquake forces do not even approach the design strength the Steel Reinforced Concrete Dome is built to withstand under normal every day usage. It would take an external force many times as large as the earth quake to approach the design strength of concrete itself.
Nuclear fallout is another disaster consideration. It is interesting to note that the only structure left standing near ground zero at Hiroshima was the skeleton of a dome. Certainly the Steel Reinforced Concrete Dome would be superior to most buildings if a nuclear fallout condition occurred. Rain would to wash the radiation off the building much better than conventional buildings.
Generally the Steel Reinforced Concrete Dome is quite tall. Radiation strengths are inversely proportional to the square of the distance from the source. The roof of the Steel Reinforced Concrete Dome would hold the radiation further from the occupants than many other structures. Also concrete itself is a good absorber of radiation. The concrete Steel Reinforced Concrete Dome would greatly reduce the effects of fallout on the occupants.
It is interesting to note that German thin shell structures stood up to allied bombing in the Second World War better than most structures. When a bomb would hit a thin shell, it would either bounce off their tough exterior or it would puncture a hole through.
Since there are no single components that carry large loads, there is nothing that can be knocked down like a beam or a column. Therefore repair was a single patch to cover the hole that was made when the bomb would go through.
["Thin Shell" is the generic name for a Steel Reinforced Concrete Dome.]