Performance of Concrete Filled Steel Tubular columns under cyclic and earthquake loading combination

The author has investigated Concrete Filled Steel Tubular columns with different conditions of compression, tension and torsion combination for more than fifteen years. In addition to the extensive research, in both experiments and theoretical Studies in China, the author also cooperated with Dr. George C. Lee in Multidisciplinary Center for Earthquake Engineering Research of New York at Buffalo. Mainly various loading combinations of tension, compression, torsion and bending acted on the Concrete Filled Steel Tubular elements has been investigated. The latter include long, medium and short elements of different steel contents, with different slenderness. strength of steel and concrete material. The total number of column Studied is more than four hundreds. The author after the experimental Studies on static, cyclic, complex earthquake action - vertical tension, compression, torsion and their combination for four hundreds Concrete Filled Steel Tubular columns, has obtained significant achievements. It further demonstrate that the circular Concrete Filled Steel Tubular column is the most promising, reliable earthquake resistant construction components. It has the highest superior characteristics over other structures, provides a wide rang of possibility to use Concrete Filled Steel Tubular in the engineering field, which makes Concrete Filled Steel Tubular a very unique position in maximize the earthquake resistance and minimize the structural damages. The author has studied in Concrete Filled Steel Tubular regarding the mechanism of its deformation, strength under the combination of static, cyclic repeat load and earthquake force. Among these conditions, the torsion force and related combination has action of extremely importance, and is usually neglected by many researchers. The author provided reliable practical formula for engineering design with theoretical proof in existence of both static and dynamic interaction. The results of these studies have not yet been fully noticed or utilized by many building code researchers and designers. The author has been emphasizing the issue for many years with great efforts through academic lectures and communications, especially in many publications based on individual examples in actual. At present, there are more and more researchers who follow and apply the author's ideas, suggestions and results of experiments in their research and engineering practices.