How should vertical reinforcing bars in columns be supported?

• A. On the ground
• B. By gravity
• C. With appropriate chairs/spacers to maintain cover and alignment as per plan
• D. Loose in air

Answer: (C)

Vertical reinforcing bars in columns must stay precisely in the position shown on the plan, with the correct distance from the formwork and from each other. This is achieved by using chairs or spacers that hold each bar at the proper height and spacing within the column form. These supports prevent movement during concrete placement and vibration, preserving the required concrete cover, alignment, and the intended development length and splice locations. Without proper chairs or spacers, the bars could shift, reducing cover or misaligning the bars, which can compromise durability and strength.