Seismic Performance Of Shear Wall Structure With Novel SMA Dampers In Coupling Beams

Shear wall is usually adopted as horizontal load resistance system in high-rise buildings. The coupling beams in shear wall structure often yield before wall limbs and dissipate large part of energy during earthquakes. At the same time, structural stiffness decrease with the yielding of coupling beams and structural periods become longer. The predominant period in earthquakes are avoided. However, the plastic deformation in coupling beams will result in damage after earthquakes. The cost in repairing the coupling beams is large, and the structure can not be used quickly after earthquake. Indirect economic loss due to the interception of social and economic activities is unpredictable. Therefore, a new type of coupling beams which can dissipate seismic energy and can restore to its original state after earthquake is needed.Shape memory alloy (SMA) is a new material with multi functions. The austenite SMA has good energy dissipation capacity under deformation. Also, its deformation can restore automatically when external force disappears due to the phase transformation inside the material. Then SMA is a potential material to develop the new coupling beams with good energy dissipation capability and good deformation restoring ability.A novel SMA damper which can endure shear deformation is proposed in this study. The austenitic SMA is adopted in this damper and the pseudo-elastic property is utilized. This novel SMA damper is installed in the middle of coupling beams and yield (and then dissipate energy) before shear wall. The deformation of the SMA damper will restore automatically after earthquakes.The main contents in this paper are as follows:(1) The super elasticity ability of NiTi SMA silk was tested. The effect of the strain amplitude, loading frequency and cyclic numbers on the super elasticity ability of SMA was analyzed.(2) One dimensional segment linear constitutive model of SMA was studied and added into ABAQUS material library. The proposed SMA-VUMAT subroutine was verified though time history analysis of a structure equipped with SMA material using complicated earthquake inputs.(3) The conceptual design a novel SMA-coupling beam was proposed. Seismic responses of a 12-story reinforced concrete coupled shear wall with and without the novel SMA-coupling beams are analyzed. Parametric analyses of the SMA dampers were performed, and the influences of SMA parameters on structural seismic responses were given.(4) The damage model and energy distribution of the new structure model was studied and the result showed that SMA damper can make the structure damage model more reasonable.