>Они глубоко внутри здания. Это декоративные элементы, рассчитанные на ветровую нагрузку.
The World Trade Center towers used high-strength, load-bearing perimeter steel columns called Vierendeel trusses that were spaced closely together to form a strong, rigid wall structure, supporting virtually all lateral loads such as wind loads, and sharing the gravity load with the core columns. The perimeter structure containing 59 columns per side was constructed with extensive use of prefabricated modular pieces each consisting of three columns, three stories tall, connected by spandrel plates.[31] The spandrel plates were welded to the columns to create the modular pieces off-site at the fabrication shop.[32] Adjacent modules were bolted together with the splices occurring at mid-span of the columns and spandrels. The spandrel plates were located at each floor, transmitting shear stress between columns, allowing them to work together in resisting lateral loads. The joints between modules were staggered vertically so the column splices between adjacent modules were not at the same floor.[31] http://en.wikipedia.org/wiki/World_Trade_Center , отсылка на http://wtc.nist.gov/pubs/NISTNCSTAR1-1.pdf
декоративными являются только алюминиевые внешние накладки.
С уважением