ABSTRACT
The spiral column is not literally a column having the shape of a spiral, a twodimensional geometric form (Figure 9.1). It is a concrete column reinforced with helical (Figure 9.2) in addition to longitudinal reinforcement. It has a circular core conned by helical reinforcement wound at a spacing that is typically not smaller than 1 in. and that rarely exceeds 3 in. In engineering use, helical reinforcement has been called spiral reinforcement, and the column with spiral reinforcement is called a spiral column. Representative spiral column sections are shown in Figure 9.3.
