Experimental Study on Seismic Performance of Steel Reinforced Concrete Columns after Axial Sustained Loading

In view of the time-dependent behavior of steel reinforced concrete (SRC) columns caused by creep and shrinkage under sustained loading，this paper provides an experimental study on the seismic behavior of SRC columns under low cyclic reversed loading，after they are subjected to axial sustained loading. Long-term axial deformations due to shrinkage and creep of the concrete were recorded，and the failure mode，deformation and strength of these columns in seismic test were analyzed. The test results indicate that the columns develope most of the creep deformation after 1 year of axial sustained loading. All columns fail in flexural-shear failure mode under the cyclic loading test. Whether or not the columns undergo sustained loading，the influence of steel reinforcement configuration and axial compression ratio on their seismic performance is similar to the conclusions drawn by previous studies. The deformation capacity and energy dissipation capacity of columns can be improved by adding steel tube in the columns. With the increase of axial compression ratio，the deformation capacity and energy dissipation capacity of columns decrease，but the shear capacity is improved. Sustained loading can lead to enlargement of yielding displacement，while it can decrease the initial stiffness and ductility coefficient in reinforced concrete columns. However，for the steel reinforced concrete columns，the influence of sustained loading on their seismic performance is restricted and weakened owing to the contribution of steel tube. Therefore，compared with the important design parameters such as steel reinforcement configuration and axial compression ratio，the influence of sustained loading on the seismic performance of SRC columns can be neglected in design. Keywords:   steel reinforced concrete,  column,  creep,  shrinkage,  seismic performance