Experimenta1 study on seismic behavior of Z-shaped reinforced concrete columns subjected to biaxial bending and axial compression

In order to study the seismic performance of Z-shaped reinforced concrete columns,cyclic loading tests were carried out on nine 1/2 reduced-scale specimens and monolithic loading tests on two specimens.The effect of axial compression ratio(n=0.30,0.45),lateral loading direction(α=0°,45°,90°,135°),web depth-thickness ratio(3∶ 1,4∶ 1) and strength of the longitudinal bars(HRB400,HRB500) were studied.And the failure characteristics,mechanical behaviors of Z-shaped section columns such as the loading-displacement hysteretic loops and skeleton curves,load bearing capacity and displacement ductility were analyzed.The experimental results indicate that the major failure made of the tested column is flexural failure,and the destruction mainly occurs at the mid-span cross-section which parallels the force direction.The hysteretic loops of Z-shaped section columns are symmetric and plump.The specimens have good ductility,indicating excellent seismic behavior.A computer program aiming at obtaining the bearing capacity of Z-shaped columns under axial compression and biaxial bending was compiled.The analytical results are in good agreement with the test results.