Comparative Study On Seismic Behaviour Of SMA Braced Steel Frame And BRB Steel Frame Based On IDA

In this paper,the seismic response characteristics of the self-centering frame are studied,and the buckling-restrained braced frame is selected as the reference object.The incremental dynamic analysis method is the main research method.The core component of the self-resetting brace is a shape memory alloy.Before carrying out the seismic analysis of the system,a buckling-restrained damper with shape memory alloy and low yield point steel as the core component is firstly proposed in this paper.In this component,the buckling-restrained damper acts as an energy-consuming part to dissipate the input seismic energy,and the shape memory alloy provides a self-centering function to reduce the post-earthquake residual deformation of the structure.A finite element model of the buckling-restrained self-centering damper was built using the finite element analysis software ANSYS Workbench.The low-cycle repeated displacement loading was used to simulate the nonlinear static behavior of the component after earthquake.The hysteresis curve was obtained and compared with the existing experimental result.At the same time,the instantaneous dynamic elasto-plastic response and high-order buckling behavior of the component under earthquake are simulated by transient analysis.Based on this,the size of the model was changed by single-variable control.And the influence of size factors,such as model radius and the length of the flexion segment,on the effectiveness of the buckling-restrained self-centering damper was studied.Comparing the simulated values with experimental values and typical steel components' experimental values,the addition of shape memory alloys to the dampers reduces greater maximum and residual deformation than the conventional buckling-restrained dampers.Therefore,this component has certain engineering application prospects for areas with high seismic intensity and large-span structures.In the seismic analysis,a suite of 20 ground motion records developed for Los Angeles area of California were selected.The finite element model was built in the earthquake simulation platform OpenSees.The seismic response indexes mainly investigated include:peak interstory drift ratio,peak floor acceleration,residual interstory drift ratio.A single-degree-of-freedom structure and a multi-story braced frame representing the multi-degree-of-freedom structure are analyzed respectively.The seismic analysis shows that due to the low energy dissipation of the self-centering structure,the seismic response of the former tends to be greater when the self-centering braced frame and the buckling-restrained braced frame have the same elastic behavior and post-yield stiffness ratio.The parametric analysis of the post-yield stiffness ratio shows that:1)the peak displacement of the structure can be effectively controlled by increasing the post-yield stiffness;2)the peak floor acceleration of the structure does not increase due to the increase of post-yield stiffness;3)the input seismic energy is almost constant;4)with the increase of the post-yield stiffness,the seismic response dispersion and the interstory drift ratio of the structure are significantly reduced.