Seismic performance of beam-column joints with SMA tendons strengthened by steel angles

Shape memory alloys (SMAs) are a class of intelligent materials with unique shape memory property and super-elastic property. These properties enable SMAs to be employed for re-centering and energy dissipative purposes in seismic-resistant structural frame. This paper in particular examines the structural performance of joints between CHS column and I-beam equipped with 12 mm diameter SMA tendons and steel angles. Two full-scale laboratory tests were conducted to investigate (1) the re-centering capability contributed by the SMA tendons and (2) the energy dissipative performance contributed primarily by the steel angles. Parallel numerical and parametric analyses through ANSYS were also conducted. Both experimental and numerical results confirmed the significance of the thickness of the steel angle and the initial prestress on the SMA tendons towards the connection's stiffness, re-centering and energy dissipative performance. A thinner angle resulted in lower connection stiffness and a lower energy dissipative ability, however a promising re-centering capability was guaranteed. Higher initial prestress on the SMA tendons also facilitates the re-centering performance.