Design considerations for long-span concrete floors

This paper reviews and discusses design issues related to long-span concrete floor systems. The primary issue to be dealt with is serviceability considerations since design for safety is generally treated rationally with well-established guidelines. On the other hand design for serviceability (particularly deflection control and vibration control) is often not addressed or handled by empirical rules, or rules of thumb based on previous experience. As floor spans tend to increase due to the use of higher strength materials and more sophisticated analysis techniques, experience-based empirical rules may be no longer applicable. For example it will be shown that minimum thickness rules in the ACI Code are only valid in certain span ranges. Also for shorter spans, vibration control is rarely an issue but may be a governing factor for longer spans. The need for further investigation of these issues by the design and research communities is emphasized.