Experimental Research On Seismic Behavior Of Thin-walled Steel Tubular Columns Filled With Recycled Aggregate Concrete

The mechanical properties and durability of recycled concrete structure is lower than that of normal concrete, which limits recycled concrete used widely in building structures. The thin-walled steel tubular recycled concrete composite structure is formed by priming recycled concrete into thin-walled steel tubular. The composite structure has two advantages:Firstly, the capacity of recycled concrete increased, because of the core concrete in three stress state by using of the confinement effect of steel; secondly, resulted from recycled concrete in a confined space, the durability of recycled concrete improved. The composite structure makes steel and concrete weaknesses, becoming an effective structure.The paper was conducted to study seismic behavior of specimens by experimental and theoretical analysis of circular and square thin-walled steel tubular columns filled with recycled aggregate concrete under axial load and cyclic lateral load.(1) Experiment of two circular and two square thin-walled steel tubular columns filled with recycled aggregate concrete under axial load and cyclic lateral load was conducted. The experiment was conducted to study the failure pattern and hysteretic performance of the columns, and analyze their seismic behaviors, such as bearing capacity, stiffness degradation, ductility, energy dissipation capacity and so on. The experimental results show that the steel tube wall which is less than 200mm away from the roots of the columns is buckling when the specimens destroy. The hysteretic curves of the specimens are plump in shapes under low cyclic load, and the ductility coefficient is around 4.0. These illustrate circular thin-walled steel tubular column has good ductility and energy dissipation.(2) On the basis of experiments, the nonlinear numerical simulation of the test process was conducted by using the finite element software ABAQUS. The simulated curves like hysteretic curves, skeleton curves and stiffness degradation curves were compared with the experimental curves. The results show that numerical results are in good agreement with experimental results. These illustrate that the model can simulate the actual loading process of steel tubular structure accurately.(3) On the basis of experimental and finite element analysis, the paper proposed theoretical models of hysteretic curves、theoretical models of trilinear skeleton curves and simplified calculation method of ductility factor, and the specimens were verified. The results show that theoretical analysis results are in good agreement with experimental results. These illustrate that the theory can be used for theoretical analysis of seismic design.