Behavior of new types of flange connectors of precast double-tees

Double-tees are often used as roof and floor systems in commercial buildings and parking garages, and they are often joined with mechanical connectors to form a floor system. The properties of flange-type connectors directly affects the in-plane behavior of double-tee diaphragms; however, most of them have been developed through field experience with undependable capacities, despite such connectors having been extensively applied in practice. Five new types of connectors were constructed, and a total of 15 connector tests were conducted under a variety of loading conditions with both monotonic and cyclic reversing in-plane shear. The load–deformation relationship, stiffness, energy consumption capacity, and shear capacity of the five new types of mechanical connectors were obtained. The results show that the seismic performance of new types of mechanical connectors deviated from each other by large margins, and they are satisfactory for vertical loading. The test results also show that the pre-toppings can effectively improve the strength and deformation capacity for all kinds of connectors.