INVESTIGATION OF MINIMUM LONGITUDINAL REINFORCEMENT REQUIREMENTS FOR CONCRETE COLUMNS USING PRESENT-DAY CONSTRUCTION MATERIALS. PAPER BY PAUL H. ZIEHL, JEFFREY E. CLOYD, AND MICHAEL E. KREGER. DISCUSSION.

This brief article comments on a study that was carried out to assess the feasibility of reducing the current ACI Building Code and AASHTO Bridge Specification requirements for minimum longitudinal reinforcing steel in columns. The aim was to determine the effects of modern-day construction materials on minimum reinforcement requirements. In this discussion, Russell congratulates the authors on their research to reassess the minimal longitudinal reinforcement requirements for columns since materials and concrete strengths have changed considerably since the original research was performed. Russell then discusses conclusion number 3, in which the authors state that a reduction of the current ACI Code requirement is not justified by the study. Russell considers whether this conclusion is applicable to full-size columns in real structures. Appended to Russell's commentary is a response from the original authors in which they recommend caution in extrapolating from results of the testing program to full-size columns, especially for columns constructed with high-strength materials.