Conversation so far:
What was the tube structural system?
His "tube concept", using all the exterior wall perimeter structure of a building to simulate a thin-walled tube, revolutionized tall building design.
Did this system do well?
Most buildings over 40 stories constructed since the 1960s now use a tube design derived from Khan's structural engineering principles.
Was this system used for anything else?
Tubular systems allow greater interior space and further enable buildings to take on various shapes, offering added freedom to architects.
Was there anything else interesting about the article?
Another important feature of the tubular systems is that buildings can be constructed using steel or reinforced concrete, or a composite of the two, to reach greater heights.

Question: What else can you tell me about the tubular systems?
Self-contained rewrite: What else can you tell me about the tubular systems besides revolutionized tall building design?