Experimental investigation on hysteretic behavior of planar and 3D joints in cruciform SRC column frame

In order to research the hysteretic behavior of steel reinforced concrete (SRC) special shaped column frame joints in the interior columns, low cycle reversed loading tests of four planar interior joint specimens and three 3D interior joint specimens were conducted. The main test parameters about column cross-section steel form and horizontal loading angle were considered. Seismic performance indicators, such as the failure patterns, hysteretic loops, bearing capacity, energy-dissipating and ductility index, were contrastively researched. The results show that the failure mode of SRC special-shaped column frame planar interior joints is shear failure in the joint core, and there is an inbibitional effect of two side column limbs perpendicular to the loading direction on the oblique fracture penetration. While the 3D interior joint is the shear diagonal destruction accompanied by bond failure. Compared with the planar joints, the hysteretic loop of 3D joints is much plumper, and their ductility and energy-dissipating are large enough, but their bearing capacity trends to be reduced. The shear bearing capacity for planar and 3D joints in the cruciform SRC columns are put forward, and the calculation results are in good agreement with test results.