Finite Element Analysis On The Damping Ratio And Seismic Performance Of Rubber Concrete Filled Steel Tubular Columns

The energy dissipation capacity of the building construction in the process of earthquake plays an important role in keeping the safety of buliding structures. Therefore, how to improve the energy dissipation capacity of the structures is one of the important issues which we are confronted with.The composite structures with CFT columns, combining the advantages of high bearing capability, good ductility, and significant economic benefit, are widely adopted in the high-rise and super high-rise bulidings. In the previous researches, it was discovered that the bearing capacity of CFT columns did not decrease significantly after yielding. Based on this discovery, P.Z. Xu and A. Kawano proposed the hybrid mechanism, which allowed parts of CFT columns to yeild to dissipate energy. In order to improve the energy dissipation capacity of CFT columns and recycle the waste rubber, a new structural component, rubber concrete filled steel tube (RCFT) column, is proposed. Owing to the restraining effect of steel tube, the bearing capacity of core rubber concrete enhances significantly. In addition, the rubber which belongs to viscous-elastic material results to the increase of energy dissipation capacity of yield columns. The RCFT columns can dissipate seismic energy effectively, thus, the building construction can avoid to be destroyed in the earthquake.In the paper, experimental studies and theoretical analysis are conducted to obtain the inherent frequency and damping ratio of RCFT columns with different rubber content and aixal load. Based on the results, elasto-plastic dynamic and time-history analysis method are applied to research on the influence of damping dissipation energy on the seismic performance of hybrid mechanism frame structure. The main objectives of the research are as follows:Four RCFT columns are tested in the research. Rubber content and aixal load ratio are taken as the main experimental parameters. Rubber content equals to0%(ordinary concrete),10%,20%, and30%respectively. And axial force ratio equals to0,0.2,0.4,0.5respectively. The time domain waveforms of RCFT columns are measured by free vibration method. And time domain analysis method is applied to obtain the frequency and damp ratio. The experimental results show that the increase of the damp ratio tends to the greatest when the rubber content is20%. The cantilever state of RCFT columns changes after axial force is applied. Thus, it has great influence on the frequency and vibration mode of the columns, however, damping ratio still increases with the increase of the rubber content.SNAP, a software of finite-element analysis, is selected to simulate the experiment of damp ratio tests of RCFT columns. Thus the frequency and vibration mode of the columns are obtained. The analysis results obtained by SNAP coincide with the experimental results in the case that the specimens are under the state of freedom vibration. However, in the case that the specimens is under axial load, the analysis results have some differences with the experimental results due to the complexity of loading device.Time-history analysis method is adopted to study the effect of damp ratio on the story drift, energy dissipation of frame structure, the deformation and shear force of columns. The results show that the increase of damping ratio of yield columns has significant effect on decreasing story drift and increasing the energy dissipation of the frame structures. Therefore, seismic safety of the structures enhance significantly.