Seismic behavior of steel encased reinforced concrete beam-columns

Nine steel encased reinforced concrete beam-columns were tested to investigate their seismic behavior when subjected to constant or varied axial load and repeated lateral loading. Three experimental parameters were taken into consideration: shear aspect ratio, axial load level, and axial loading history. The test results showed that there were no remarkable effects of shear aspect ratio on flexural strength and deformation capacity of the beam-columns. Meanwhile, the axial load level as well as axial loading history was found the most influential factors. An analytical method was proposed to simulate the seismic behavior of the beam-columns. In the analysis, effects of shear aspect ratio on initial stiffness and confining effects of lateral reinforcement on concrete were taken into account. Comparisons of analytical and experimental results verified that the proposed analytical method could successfully simulate the seismic behavior of the steel encased reinforced concrete beam-columns.