Masonry Magazine August 1982 Page. 9
FRAME SHORTENING and the STONE CURTAIN WALL INDUSTRY
A nationally known structural engineer reports that frame shortening in highrise buildings is causing both lost time and dollars. And yet, much of this waste could be avoided with proper awareness on the part of the construction industry and its professionals.
By Robert Rosenwasser, P.E.
Robert Rosenwasser Associates, P.C., New York City, N.Y.
When a high-rise building is built, certain phenomena occur in the materials of construction that result in a shortening of the building's frame. Today, as we design and build taller and taller structures, this effect has become highly pronounced, especially in tall concrete buildings. During and after construction of a 60-story concrete building, its roof can lower as much as a foot from its theoretical elevation as each floor shortens within its own height and towards the foundation. This happens more in concrete construction than in steel because vertical concrete members tend to shrink and creep over a long period of time and are subject to shortening of the vertical forming components (formwork) during construction as well. It is also significant to note that in both steel and concrete buildings compression of the columns due to the load put on them results in what engineers call elastic shortening. Therefore, as constructed, no building will have continued on page 30