OBSERVED DEFLECTIONS OF REINFORCED CONCRETE SLAB SYSTEMS, AND CAUSES OF LARGE DEFLECTIONS.

This report is in two distinct parts. Part I is a summary of published studies on slab deflections. The summary focuses on construction practices and materials quality. Part II summarizes several construction problems and material deficiencies which can contribute to large long-term deflections. Focusing on large construction loads, the authors show that construction loads may be considerably higher than design loads and that high construction loads cause high initial deflections because concrete has a lower modulus of elasticity when loaded at an early age. Furthermore, concrete creeps more when it is loaded at an early age.