Experimental study on compression bending property of casing joint of concrete filled steel tubular supporting arch with square section

In order to obtain the compression bending characteristics of casing joint on the square steel tube confined concrete supporting arch,by considering the four influencing factors as concrete strength,length and thickness of the casing pipe and the gap of the casing joint,the orthogonal test schemes were designed. ABAQUS was used for the nu- merical tests,and the laboratory tests were carried out to verify the simulation results. The deformation mode of casing joints under eccentric load was analyzed. The Mu -Nu curves were drawn based on the tests results,and the compression bending bearing capacity formulas were obtained by fitting method. Orthogonal analysis was carried out and it was found that:the concrete strength and casing joint length are the main factors that affect the bearing capacity and flexur- al capacity respectively,and the effect of the other factors are very small;the axial bearing capacity and flexural capac- ity of the test members with casing joints are lower than the one without casing joint about 30% ,and the shorter the casing pipe the lower the bearing capacity.