Study On Seismic Behavior Of Concrete-filled Square Steel Tubular Column To Steel Beam Connections With Anchorages

There were some special properties of the concrete-filled square steel tubular structures, such as high-strength, light weight, better fireproofing behavior, excellent seismic performance, rectangular geometry and they could be easily to design and construct, so they were more and more popular in the world. While the research on this structure was preliminary in our country and the joint patterns which could be adopted were few. In this paper, the concrete-filled square steel tubular column to steel beam connections with anchorages as a new type was studied. The web plates of the T-shaped anchorages were upright which were welded in the steel tube and vertical with the flanges of beam.In this paper, the three of this type of connections were tested under low cyclic loading to review seismic behavior of them and the failure modes, ductility, energy dissipation capacity, degradations of strength and stiffness of them under different axial-compression ratios were compared. The 3D models of this type of connections were founded by the finite element program ANSYS 9.0 and the capacity behaviors of connections which were under monotonic loading were analyzed. The results show the stresses distribution in the details. The difference of the load-displacement curve and the skeleton curve which were obtained from experimental research were analyzed and the results of finite element analysis were tally closely with the test results. Then, the influences of axial-compression ratios or strength classes of concretes on joints capacity behavior were analyzed.Based on the achievements in theory and experimental researches in this paper, the seismic behavior of concrete-filled square steel tubular column to steel beam connections with anchorages were discussed. When the horizontal load on the top of column was less, the seismic behaviors of the connections were better. While when the load was larger than yield limit load, the welds of column were torn and the concrete was crushed and the capability of connection was degenerated. So, connections of this kind could be adopted when the horizontal load was less.Design suggestion, detailing requirements and job practice were recommended. They could be referred in engineering design.