The project consisted of two 110-story twin towers.  When originally constructed, the 417 meter  tall towers were the world’s tallest buildings. 

 

A listing of the innovations incorporated into the World Trade Center is over long.  Still, listing just a few of the ideas and innovations conceived and developed by LERA:

 

- The tubular framing system for the perimeter wallresisting all of the lateral forces imposed on  the building;

- The introduction of the outrigger system;  structurally linking the outside wall to the services core;

- The prefabrication in structural steel to a degree

 never before achieved;

- The use of the boundary-layer wind tunnel for predicting both steady-state and dynamic forces on structure and on glazing, and for developing the dynamic component of wind-induced structure motion;

- Motion-simulators to determine acceptable levels of wind-induced structure motion;

- The viscoelastic damping system, effectively dissipating the dynamic component of building motion;

- The development of a theory to predict the breakage rate of glass under the dynamic forces of the wind;

- The development of a theory to predict stack action and both temperature- and wind-induced airflow within a high-rise building;

- The first structure outside of the military and the nuclear industries designed to resist the impact of a jet airliner;

- The concept of the fire-rated shaft Wall partition system, which partition has replaced masonry and plaster walls… at the time the standard enclosure for elevators, stairs, duct shafts and the like.