Seismic Behavior, Design, and Analysis of Short-Grouted Ductile Rebar Connections for Precast Concrete Structures

This dissertation presents an investigation of precast concrete shear walls with nonproprietary, short-grouted connections for ductile energy-dissipating reinforcing bars crossing horizontal joints. Unlike available proprietary grouted splices that use end-threaded reinforcing bars for force transfer along the splice, the energy-dissipation bars in the proposed connection are terminated and grouted inside straight corrugated thin-gauge steel ducts. Vertical, transverse, and longitudinal tie reinforcement is designed around the connectors to transfer the energy-dissipation bar forces into the precast component. The research included six large-scale shear wall test specimens, numbered as specimens 1-6. Specimen 1 was tested by a previous Master’s student at the University of Notre Dame. All six specimens were tested and evaluated under pseudo-static reversed-cyclic lateral loading and superimposed axial loading per seismic acceptance criteria for special precast concrete shear walls in ACI 550.6-19. Specimen 1 was designed based on previous tests of isolated (that is, single) energy-dissipation bar connections subjected to reversed-cyclic uniaxial loading. The results from each wall test informed the design of the subsequent specimens. Among the first three walls, only specimen 3 satisfied the maximum lateral strength loss limit of 20% at the validation-level drift prescribed by ACI 550.6-19. Important connection design and detailing recommendations were made based on the performance differences between these specimens. Specimens 4, 5, and 6 were tested to evaluate the connections for varying energy-dissipation bar size, wall base moment-to-shear ratio, wall thickness, axial load ratio, and layout of connectors and tie reinforcement in the wall cross section. These specimens met all applicable validation requirements of ACI 550.6-19, sustaining limited damage despite undergoing large lateral displacements, and demonstrating high performance of the connectors for seismic application. The wall test results were used to improve a previous strut-and-tie model for designing the connection tie reinforcement and connector length. A simplified set of equations and accompanying sample calculations were created for engineers to design connections without engaging into the details of the strut-and-tie design model. Fiber element-based nonlinear numerical models as well as closed-form analytical approaches to predict the nominal and probable axial-flexural strengths of walls utilizing these connections were also developed.