Fazlur Rahman Kahn....

[BaalChatzaf]

Today is the 88 th birthday of Fazlur Rahman Khan  and engineer-architect who  developed the  truss or bundled tube concept.  This  meant that once again the outer wall of a tall building could bear weight.  This turned the skyscraper  inside out.  The erection of tall buildings  (ten or more stories)  started in Chicago.  The concept was that a steel frame (a skeleton of sorts), a rigid structure would  be the load bearing  element of a building and the outer walls would be the covering, the element that separated the inside of the building from the outside.   The walls would not bear the weight of the building,  the frame would.  And from that time to about the 1960's that is how skyscrapers would be built.   

Then Khan  looked at the problem of stress bearing  and  realized that a thin walled tube properly bound  and trussed  could  bear the load.  This led to a whole new type of tall  building.