Seismic behavior and design method of tubed reinforced concrete (RC) beam-columns

To investigate the seismic behavior and design method of tubed reinforced concrete (RC) beam-columns,circular tubed RC (CTRC) and square tubed RC (STRC) columns were experimentally studied. Results indicate that CTRC and STRC columns with high axial load ratio exhibit much higher flexural strength,displacement ductility and greater energy dissipation capability than common RC columns due to the effective confinement of the tube to the core concrete. The moment strength and ductility of CTRC columns are higher than those of STRC columns with the same axial load ratio and diameter-to-thickness ratio. The design method for steel tube confined RC beam-columns is proposed based on the experimental results. Fiber models are developed for CTRC and STRC beam-columns,and the analysis results of fiber models agree well with the experimental results.