UCSD Jacobs School of Engineering University of California San Diego
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UCSD Structural Engineers Design Weld-Free Steel Frame

A large crack runs horizontally through the now mangled steel column as a result of damage to the traditional welded joint between the beam and the column caused by the 1994 Northridge earthquake (D.P. O’Sullivan).

Structural engineers at the Jacobs School have applied post-tensioning, a technique commonly used in the construction of concrete buildings and bridges, to create a new class of weld-free steelframed structures. The initial 2001 test indicated that the post-tensioned steel frames can absorb strong earthquake motions with little or no damage. “By adding tremendous tension to rods that run horizontally through the beams and columns, squeezing them together like an elastic band, a steel frame can be constructed without welded joints,” says André Filiatrault, professor of structural engineering.

“Strong post-tensioned rods clamp the beams to the columns, holding them together,” explains doctoral student Constantin Christopoulos. “These high-strength rods provide the spring force, which allows the system to return to its initial position after an earthquake.” The next test, scheduled for this summer, will study the behavior of a post-tensioned steel frame supporting a concrete slab during earthquake-like conditions. As they prepare for the large-scale test, Filiatrault and Christopoulos are collaborating with Professor Chia-Ming Uang who continues to be a valuable resource on steel design issues. To see video, visit http://www.jacobsschool.ucsd.edu/news/news_releases/2002/20020404.shtml.