A Type Ⅲ Tapered-Cylindrical Grouted Splice for Energy Dissipation Bars in Seismic Precast Concrete Joints

摘要

This paper presents the results from a recent experiment of a novel grouted Type Ⅲ splice for reinforcing bars in gap-opening joints of seismic precast concrete structures (e.g., joint between a precast wall panel and the foundation). Section 18.2.7 of ACI 318-14 allows Type Ⅱ splices for reinforcing bars at any location in a building, including yielding energy dissipation (ED) bars in plastic hinge zones. However, the certification requirements for Type Ⅱ splices in the U.S. do not match the high cyclic strain demands that are possible in gap-opening precast concrete joints under extreme seismic loading. The use of short grouted splices simplifies the construction of these structures because protruding bar lengths from precast members can be minimized and field grouting lengths can be reduced. The experiment was conducted with the primary objective of developing a high-performance, but relatively simple, non-proprietary splice that can allow ED bars under cyclic loading to reach close to their full ultimate strength and fracture strain capacity over a short grouted development length. The tested bar, which was subjected to cyclic tension loading inside a tapered-cylindrical grouted splice, fractured (without pullout) during the 5th cycle to a maximum strain of 0.90ε_(su), where ε_(su) is the measured monotonic strain capacity of the bar at peak strength. This result demonstrates that ED bars with tapered-cylindrical grouted splices can achieve similar performance as bars with fully-embedded development lengths.