| Nowadays as requirements become increasingly high of architectural structures, their forms become more complicated, beam-column abnormal joints have been increasingly adopted in large-scale industrial and civil constructions. However, for absence of experimental and theoretical research national relevant specifications are still in the blank in this area now, and there is also no reliable method for its design. So investigate on this kind of steel frame beam-column joints have important theoretical meaning and practical values.This paper focuses on seismic behavior of steel frame beam-column joints with an offset in right and left beam positions strengthened external diaphragm. The model is designed to meet specifications "strong component weak node" by means of computation. The difference between the panel zone and the top and bottom panel zone were analyzed and compared. The joint panel zone is divided into three parts, including the middle panel zone as well as the top panel zone and the bottom panel zone symmetrically. Finite element analyses of the joints are performed using ABAQUS computer program. The stress distribution and the law of development of the joint panel zone under low-cyclic reversed loading are obtained, and the different behaviors between the middle panel zone and the top panel zone as well as the bottom panel zone are analyzed and compared.Test specimens are produced in the same size of the design model and tested under low-cyclic reversed loading. The impact of variation of the area parameter of external diaphragm, the offset value in right and left beam positions, different column cross-section forms on the seismic performance of abnormal joints are investigated. Bearing capacity, deformation performance, hysteretic behavior and failure mode of the abnormal joints are obtained and compared with the normal joints at the same time. The results of the dynamic cyclic test showed that:these kind of abnormal joints possess good ductility performance, energy-dissipating capacity and seismic performance. In the last stage of the displacement loading, although obvious shear deformations appear in the panel zone, the joints still remain well entirety.This study reveals the seismic performance and the yield failure mode of the steel frame beam-column joints with an offset in right and left beam positions strengthened external annular plate through tests and numerical simulations. The study results will provide references for the design and practical application of beam-column abnormal joints, and be helpful for the further research on the abnormal joints. |
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