Research in Engineering and Aviation

Torsionally Loaded Circular Concrete Member Confined with Spirals

March 2011

Author(s): Hindi, R., and Browning, B.

Journal: Structural Journal, Vol. 108, No. 2, March 2011, pp. 139-147.


Circular concrete members were reinforced with a conventional single spiral and a new confinement technique consisting of two opposing spirals (cross spirals). Eighteen members were studied under pure reverse cyclic torsional loading to investigate advantages of the new confinement technique. Cross spirals allow improved strength and ductility or increased spiral spacing to aid concrete aggregate passage during construction. Members with conventional single-spiral and new cross-spiral reinforcement schemes were constructed using identical methods and materials. All members had diameters of 200 mm (8 in.); lengths of 1000, 800, 600, and 400 mm (39, 32, 24, and 16 in.); and spiral spacings varying from 25 to 90 mm (1 to 3.5 in.). Results from cross-spiral members are compared with those of single-spiral members to evaluate the performance of the new cross-spiral confinement technique.