Luksha and Nesterovich 1991
The behavior of large diameter CFT members under axial compression was investigated and the authors noted some of the failure peculiarities of the specimens. The discussion of the large diameter failures was quite detailed.
Experimental Study, Results, and Discussion
Ten sets of specimens were tested, 3 CFT and 1 HT in each set. The main parameter of interest was the diameter of the tube. Each set had a different diameter varying from 6.25 in. to 40.2 in. The steel tubes were welded and filled with heavy concrete of unspecified weight and the L/D ratio was 3. Two types of failure were recognized in the study. Small diameter tubes were characterized by local buckling around the end of the specimen accompanied by crushing of the concrete in this zone. The large diameter specimens failed in shear. The failure began at 90% of the ultimate load by the formation of buckles along the cylinder's diagonal. The failure lines on the tube shifted before failure, and an oblique crack formed in the concrete at about a 25 to 35 degree angle to the vertical. Just before the shift occurred, the radial compressive stresses in the concrete reached their maximum value. The concrete shifted and the load between this point and failure increased very little as the steel buckled. The authors alluded to analytical results from an earlier paper and compared their experimental results to these values.
Reference
Luksha, L. K., and Nesterovich, A. P. (1991). “Strength of Tubular Concrete Cylinders under Combined Loading.” Proceedings of 3rd International Conference on Steel-Concrete Composite Structures, Fukuoka, Japan, 67–71.