Evaluation of Minimum Longitudinal Reinforcement Requirements for Reinforced Concrete Columns

Paul H. Ziehl, Jeffrey E. Cloyd, and Michael E. Kreger


Existing minimum longitudinal reinforcement requirements for columns were developed to prevent passive yielding of reinforcement resulting from creep deformations in the concrete. Tests used to support this limit were conducted decades ago when steel yield strengths for reinforcing bars were approximately half of what is common today. The design of a very large percentage of columns in TxDOT bridges is typically controlled by minimum eccentricity of loads, implying a substantial reduction in column steel and resulting economic savings might be possible with present-day materials.

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