Behavior of Autoclaved Aerated Concrete (AAC) floor diaphragms subject to in-plane reverse cyclic loading

Autoclaved Aerated Concrete (AAC) is a lightweight, cellular concrete made from cement, fine aggregate, gypsum, water, quicklime and an expansive agent. The materials are mixed into a slurry and placed into molds, where a chemical reaction takes place causing the slurry to expand and form a hard crystalline structure which is cured in an autoclave. AAC was recently introduced into the United States and its behavior within structures must be examined to confirm designs approved by codes. Behavior of floor diaphragms subjected to reverse cyclic loading, to simulate seismic loading, was examined in this research due to limited research completed on this topic.;Half-scale AAC floor diaphragms were constructed using standard construction methods and tested. Two of these specimens were subjected to monotonic loading, while four specimens were subjected to reverse cyclic loading. Specimens were constructed in identical ways except that two monotonically tested specimens had different confining reinforcement in the lower bond beam. In addition, two specimens were constructed with Class 6 AAC blocks 8-in. thick (200 mm) while the remaining four specimens were constructed with Class 4 AAC panels 6-in. thick (150 mm). Displacement of the specimen and steel reinforcement strains were measured during testing.;The floor diaphragms tested cyclically exhibited significant force and displacement capacities, even after many cycles of loading. These specimens carried load in excess of that carried by a similar specimen monotonically tested. The research completed suggests that floor diaphragms constructed of AAC are capable of withstanding the deformations and forces likely imposed on the diaphragm during an earthquake.