How is a spiral reinforcement configured?

Spiral reinforcement is specifically designed to enhance the structural integrity and ductility of concrete elements, particularly in columns and certain types of foundations. The correct configuration involves continuously wrapping the spiral reinforcement around the longitudinal bars, which contributes to effective confinement of the concrete.

This continuous wrapping around the bars helps to prevent buckling and enhances the concrete's ability to withstand lateral loads. By confining the concrete within the spirals, it effectively increases the composite strength and improves the overall load-bearing capacity of the concrete element. This method is particularly useful in seismic areas where lateral forces are a concern.

Other configurations, such as randomly placing the reinforcement, alternately hooking it at each end, or laying it flat on the concrete surface, do not provide the necessary continuous support and confinement that spiral reinforcement is intended to achieve. These alternatives do not effectively engage the concrete in the way spiral reinforcement does, leading to decreased structural performance and stability.