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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Cyclic Performance Characterization of Large Diameter Steel Reinforcing Bars and Mechanical Couplers

The large strain cyclic response characteristics of large diameter bars, such as size #18, and of the various mechanical splices used with them remains largely unknown. Large strain cyclic load testing of large diameter bars and of mechanical splices for these bars has proven difficult, and questions about the use of these bars in the construction of bridge piers remain unanswered. Large-diameter bars continuous or mechanically coupled, have been rarely used as longitudinal reinforcement in large-diameter bridge reinforced concrete piers in modern times in our state. California Department of Transportation's (Caltrans) has expressed interest in increasing the use of large diameter bars in the construction of bridge piers as one of many incentives to accelerate bridge construction in the State. More recently National Cooperative Highway Research Program (NCHRP) 698 has stated an urgent need to characterize large bars and their mechanical couplers under reverse cyclic loading. When using precast concrete construction or construction techniques aimed at accelerating the construction process, the mechanical splicing of these large diameter bars could be advantageous in some particular cases. The lack of knowledge about their cyclic load response, and in particular, of the fatigue life of the bars and of the various mechanical splices available continues to hamper widespread use of these large diameter bars.