Research On Static And Hysteretic Behavior Of Cross Baffle Welded Joints

Cross baffle welded joints as a new node, has been applied in practical engineering, but at present bout static and hysteretic performance of such joints to study less, seriously restricted the development and engineering application of design theory of this kind of joints.Study of the static and hysteretic performance of cross baffle welded joints can help to better understand the mechanical properties and failure characteristics of it and to provide theoretical basis for designers. It is theoretically significant and practically valuable in the engineering.In this paper, the mechanical properties and failure mode of different cross joints are mainly studied through the static and quasi-static test of cross baffle welded joints considering different types of axial-compression ratio as well as geometric parameters. Moreover, the FEA model was established based on the test and can be used in the follow-up research. The main content can be divided into four parts.Firstly, the material parameters from7different kinds of long-span joints, the parameters are calibrated based on the Chaboche mixed strengthen theory. These results are validated through the FEA software ABAQUS, which can be regarded as the foundation of the followed work.Secondly,3full-scale static tests of the cross baffle welded joints are conducted to study the static mechanical performance and failure mode under different load conditions. The results showed that the joint can be buckled when the two adjacent perpendicular steel pipes were both under compression, can be in strength failure when the two adjacent perpendicular steel pipes were under different load conditions and both under tension. The ultimate capacity and ductility of the joints were increased in this load order.Thirdly,4full-scale quasi-static joint tests were conducted to study the effect of some key parameters such as axial-compression ratio, the thickness of joint plates, the size of steel pipe on the hysteretic performance and failure mode of the joints. The results showed that the ultimate capacity, the accumulative ductility and the energy dissipation value would be decrease as the increasing of the axial-compression value, decreasing the thickness of joint plates and the size of horizontal steel pipe. Moreover, the rate of stiffness degeneration would be accelerated.Lastly, the paper proposed a precise FEA based on ABAQUS software included some key information such as welds and heat affection, the material parameter obtained by previous work were also used in this model. Through the comparison of the result between the FEA model and tests, it is verified that the FEA model is precise under cyclic loading, and can be used to in follow-up research work when the joints were under earthquake loads.