Urban Habitat Award Finalist: World Trade Center Master Plan, New York City

Since the first journal presentation on column shortening was published by Fintel and Khan in 1969, the topic has been drawing great attention from many engineers of tall building. They indicated that "for low/intermediate height structure, it is customary to neglect the effect...of columns and walls. As buildings reach great heights, the differential elastic shortening must be considered in the analysis, together with...creep and shrinkage. Neglecting the differential shortening in ultra-high-rise buildings may lead to distress in the structure and in nonstructural elements of the building." Nowadays, the importance of column shortening gets even higher and its computation is becoming more complex. Tall buildings are not designed in the usual rectangular box-shape any more. They are featuring irregular geometries and utilizing the capacity of composite materials and members to an extreme level, all of which contribute to increased effect of column shortening and make the engineering process very difficult.

The original idea of predicting column shortening and comparing with field observation has survived and evolved over the past 50 years, with examples of tall buildings in Chicago (Water Tower Place) and Kuala Lumpur (Ilham Baru Tower). Engineering will develop over the next 50 years with the aid of state-of-the-art technologies such as computer-aided analysis, sensors, and laser scan survey. Increase accuracy of column shortening has been achieved through recently-developed advanced construction stage analysis and linking the analysis results with the field monitoring data. This topic is useful for dealing with the issues from column shortening in future tall buildings.