This paper proposes an Adjustable Circular Steel Connector(ACS) to enable immediate response to construction errors that may occur during the on-site assembly of modular members. To evaluate its flexural performance, one rectangular steel tube beam specimen without ACS and three specimens with ACS(with varying ACS lengths) were fabricated. Experimental results showed no pull-out occurred between Shank A and Shank B, and the application of ACS facilitated stress distribution in the rectangular steel tube. The specimens with ACS exhibited up to 92% of the maximum load capacity of the monolithic specimen, and showed increasingly ductile behavior as the ACS length increased. Due to the cross-sectional difference between Shank A and Shank B within the ACS, yielding was observed in Shank B. Further studies are needed on this part, as well as on the behavior of the ACS under cyclic loading conditions.

An analytic study on the bond stress between steel tube and concrete in concrete filled steel(CFT) rectangular column is presented in this paper. Recently buildings need members which are enhanced durability and ductility. Concrete filled rectangular column system is proposed as alternative plan. In this paper, ABAQUS/Standard Version 5.8 which is identified as usefulness for finite element analysis and has various element library is used. The variables in this study are the location and type of shear-connector. The modeling on contact problem practiced by Contact Pair and Contact Pressure method. In the step of physical bond, it is practiced by Change friction option After yielding of models, analytic results is less than that of experimental results.