Seismic Performance Of RC Frame-Shear Wall Structure With SMA Re-centering Coupling Beams

Frame-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 damage of the concrete coupling beams is alleviated. The deformation of the SMA damper will restore automatically after earthquakes.The main contents in this paper are as follows:(1) Position of the SMA damper in coupling beams is addressed and construction of the damper is proposed. After that, the design parameters (damper’s yielding force to coupling beam’s ultimate shear force ratio Γ, damper’s yielding deformation to coupling beam’s net span ratio Δ and nominal stiffness of the SMA damper to coupling beam’s flexural stiffness factor ratio K) of the coupling beam with added SMA damper are proposed.(2) The Abaqus finite element model of the coupling beam subassemblage with added SMA damper is established. Monotonic and cyclic loading are applied on the coupling beam subassemblages. Influence of design parameters of the coupling beam (Γ、Δ、K) on its force condition, deformation condition and damage mode is addressed. Rational range of these design parameters is then obtained from the member design level.(3) Seismic responses of a18-story frame-shear wall structure are analyzed. SMA dampers are installed in coupling beams at each floor of the structure. The Abaqus finite element model of the structure is established. The elastic-plastic dynamic analyses of the structure with varied design parameters of the coupling beam (Γ、Δ、K) under ten seismic waves are conducted. Influence of design parameters of the coupling beam on seismic responses of the structure (roof drift, inter-story drift, absolute floor acceleration and total base shear force) and seismic responses of the member (coupling beam chord rotation, coupling beam end shear force and strain of dampers) under different levels of ground motions (major earthquake, moderate earthquake and small earthquake, defined according to Chinese earthquake resistant code) is addressed.