Seismic Retrofit of Dry Precast Concrete Beam To Column Joint Using Shape Memory Alloy
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Abstract
Superelastic shape memory alloy (SMA) is regarded as an ideal material for enhancing the seismic capacity of structures due to its superelasticity and self-centering properties. This research introduces and validates a new concept for the structural upgrade of seismically deficient precast concrete structures using SMA. The proposed approach establishes partial moment transfer at the beam-column joint, enabling the frame to partially resist lateral loads alongside the building's shear core. To achieve this, a novel device—termed the SMA Partial Moment Transfer (SMA-PMT) device—is developed and validated through experimental testing and analytical modeling using hybrid simulation. The research was executed in three stages, including model development, the experimental joint design and the experimental test. The discussion summarizes the behavior of the experimental joint specimens, focusing on joint moment capacity (yield moment), energy dissipation capabilities, and joint damage assessments. Recommendations for future research are also provided.
Description
This research proposes an innovative seismic retrofit strategy for precast concrete structures through the development of a Shape Memory Alloy-based Partial Moment Transfer (SMA-PMT) device. The system enables partial frame action at beam-to-column joints, enhancing seismic performance while maintaining constructability. The methodology integrates analytical modeling and experimental validation. A building model was developed in SAP2000 to represent an existing shear-core structure deficient in seismic design, from which target joint demands were established using pushover analysis. Component-level design of the SMA-PMT device was informed by monotonic and cyclic testing of SMA materials and refined through a calibrated joint model.
Experimental validation was conducted through six carefully designed reduced-scale tests: one cyclic loading (CL), two pseudo-dynamic loading (PDL), and three real-time hybrid simulation (RTH) tests. The loading protocols were derived directly from the analytical models, ensuring consistency between design assumptions and experimental conditions. This integrated framework enabled evaluation of moment capacity, energy dissipation, and self-centering behavior under realistic seismic demands. Results demonstrate that SMA-PMT devices significantly enhance joint performance and seismic resilience.
Keywords
Superelastic shape memory alloy, Precast concrete, Seismic retrofit, Existing structures, Scaled testing, Hybrid simulation