Experimental study on seismic behavior of Z-shaped reinforced concrete columns subjected to biaxial shearing

In order to study the seismic performance of Z-shaped reinforced concrete columns subjected to biaxial shearing,quasi-static tests were carried out on four 1 /2 scale specimens.The effects of the horizontal loading directions(α = 0°,45°,90°,135°) were studied.And the failure characteristics,mechanical behaviors of Z-shaped columns were researched.The loading-displacement hysteretic loops and skeleton curves,load bearing capacity,displacement ductility,rigidity degradation and energy dissipation capacity were analyzed.Test results indicate four types of failure patterns can be seen from the test specimens,including shear-bending failure,bending failure,shearbond failure,shear compression failure,and the shear failure ductility is very poor.It shows that the influences of the lateral bevel loads on the shear strength of Z-shaped RC frame columns can be approximately described by ellipse law.The capacity of energy dissipation is maximized in the case of 45° loading angle,and the variation is small when the loading angles are 0° and 135°.A calculation method of Z-shaped reinforced concrete columns subjected to biaxial shear bearing capacity was proposed.According to the proposed method,totally 22 sets of test data from the tests presented in this paper and other previous tests were used for the calculation.The calculation results are in good agreement with test values.