| Recycled aggregate concrete (RAC) refers to the concrete with a certain proportion of recycled aggregate, water, cement, and natural aggregate. Recycled aggregate is the waste concrete of construction process by crushing, screening and cleaning. Recycled aggregate concrete research began in the early 1950 s, but due to the specialty of waste concrete, the recycled aggregate concrete is mainly used in non-bearing structure system, such as road. For more rational use of waste concrete, integrating recycled concrete with research more mature and more widely used new type concrete filled steel tube, to form recycled aggregate concrete filled steel tube, make full use of the ferrule effect of steel tube on core recycled aggregate concrete, let the core recycled aggregate concrete in three-way compression state, make the recycled aggregate concrete has high compressive strength and deformation capacity, also the concrete filling in is used to improve the stability of the steel tube wall. At present, the study of recycled aggregate concrete filled steel tube is mainly focused on the axial compression test, bending test, the pseudo static test, load test for a long time of the component, and mainly round steel pipe, steel pipe reported research is still rare. Especially the research of seismic performance of recycled aggregate concrete filled steel tube column.In order to study the seismic behavior of recycled concrete-filled square steel tubular column.9 specimens of size 150mm×150mm were produced in this test by three factors and three levels of orthogonal method. The main parameters in the tests are the thickness of steel tube, recycled aggregate replacement ratio and axial compression ratio. The pseudo-static test was carried out respectively to attain the hysteresis curves, skeleton curves of recycled concrete-filled square steel tubular column under horizontally reverse load, and thereby analyze the bearing capacity, deformation capacity, energy dissipation capacity and failure mode of recycled concrete-filled square steel tubular column to investigate the influence of basic parameters to the seismic performance of recycled concrete-filled steel tubular column. Research findings indicate that recycled aggregate replacement ratio affect a little on displacement ductility factor of recycled concrete-filled square steel tubular column, it is mainly influenced by the thickness of steel tube and axial compression ratio especially compression ratio. When the specimens yield to load and reach the peak value, it is mainly influenced by the thickness of steel tube, in addition, it is affected by axial compression ratio when it is destroyed. Recycled aggregate replacement ration has little effect on the stiffness of the specimens.On the basis of experiment study, a large general finite element software ABAQUS was involved in the analyses of the whole loading process of recycled concrete-filled square steel tubular columns according to appropriate constitutive relation. In addition, the horizontal load-displacement hysteretic curves are simulated by finite element software OpenSEES based on fiber-model theory. The influence of each parameter on the seismic performance of recycled concrete-filled square steel tubular columns in a larger parameter range was simulated under the condition of good agreement with the experimental results. Overall, the stiffness of recycled concrete-filled square steel tubular columns at elastic stage and horizontal bearing capacity are influenced by the thickness of steel tube and axial compression ratio. In a certain range, the stiffness of recycled concrete-filled square steel tubular columns at elastic stage and horizontal bearing capacity are improved by increasing the thickness of steel tube, while decreases when the axial compression ratio is increased. The results of the test show good correlation with the experimental results. |
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