Do you have a natural fear of heights? Does your mind fill with ideas of the part where you are standing or sitting snapping off and falling? Some people get all giddy if they just lift one foot too high off of the floor, so do not be ashamed. The top part of all modern high structures move around a little bit. They are designed that way otherwise the top would indeed snap off.
One of the worst fears that any of us have is fire. In 1974, a movie was released called 'The Towering Inferno'. Badly constructed, using cheap 'below spec' materials, we watched the unfolding drama of people trapped high above ground level, some perishing, some not. Right at the end, the fire chief tells the buildings owners/designers that maybe they should get guidance from the fire department about constructing buildings where normal firefighting equipment is less than useless. It made me think at the time and, during subsequent visits to high rise buildings, the events of the movie lurked uneasily in the back of my mind. I found it difficult to shake the image of the burned out shell left standing.
We have all seen news reports of buildings around the world savaged by fire, and they all look the same, windows shattered, dark marks left by flames and smoke, eerily empty. The question as to what to do with what is left must be a problem. Is it cheaper to re-construct, or maybe to knock it all down and start over? Whatever the decision, it must first be established that the building is essentially in a safe enough state for any work to begin.
Modern design is such that construction materials used can withstand fires, wind, high impacts and even earthquakes, the weakest link being furnishings et al introduced by whoever uses the spaces inside the building. These items are generally not fireproof, and they are loose. In the event of an earthquake for instance, not only does the building shift, but so do all of the interior fittings and in a wild random manner.
If we can't prevent destructive events, what can we do to make the aftermath more easy? How would you feel about working or living in a high rise building if you knew that it had been rigged, such that in the event of a fire, it could be demolished within the hour, so saving days, weeks and months of either re-constructing or removal? It is way easier to 'rig' a building while it is still in a good state of repair. Moving debris from ground level has to be a better option than sending demolition experts and firemen into buildings where the general integrity may be severely compromised.
Fire damaged high rises never fall of their own volition because the fire is never hot enough to melt the steel used and could never be hot enough unless pure oxygen is fed directly into the fire. It has always been possible to fix the buildings afterwards.
The idea of rigging is insanity itself. Ask yourself honestly if anybody would ever sanction such a crazy idea. Lets face it, when was the last time you saw a high rise building suffer a fire and fall as a direct result of the fire damage?
Do you need help thinking back? How safe do you feel now?