EXPERIMENTAL STUDY ON MEASUREMENT OF INTERSECTION ANGLES OF FRAME CONNECTIONS BETWEEN COLUMN AND BEAM OF CONCRETE-FILLED STEEL TUBE USING DICM

The primary objective of this study is to demonstrate the feasibility of measuring intersection angle of the steel stiffening ring connection using the digital image correlation method (DICM). Due to the availability of a number of methods to connect the concrete-filled steel tube column with beam and their complex load/force transferring mechanisms, effective methods to measure the intersection angles of the connections have not been developed. DICM offers the advantages of a non-contact, high-precision, whole field system and does not add weight but is limited by its measuring range excluding large rotation and deformation. According to the features of the beam, column and their connection, shape functions in global co-ordinates are generated and used. From the modal experiment of the steel stiffening ring connection for concrete-filled steel tube column and beam frames, an improved DICM is used to investigate the relation between bending moment and intersection angle of the connections. The final results include the relationship between the bending moment and the rotational angle for different sections of the tube as connected to the column. Those include the joint points between the column and the stiffening ring, the stiffening ring and section of the beam and the section away from the stiffening ring on the beam (the distance equals to the height of the beam). By virtue of the analysis of the modal experiment, DICM is proved to solve the problem and find the exact intersection angle in the connections.