Finite Element Analysis Of The Beam-column Joint Of Steel Structure In Considering Temperature Influence

With the rapid development of technology in the construction industry, steel structure has been widely used in architectural constructions. The records of Northridge earthquake in the United States and the Hanshin earthquake in Japan showed that the damage of the steel frame structure in the earthquake mainly represented as the damage of the welding beam-column connections. The shape and the kind of this damage are closely relevant to the construction details of the nodes. The scallop structure is the primary cause of the stress concentration, as well as the influencing factor of welding line quality. It is necessary to carry out rigorous calculated analysis and experimental study.On the base of the existing experiments, and with the help of ANSYS finite element software, this study focuses on comparing the welding composite steel-beam with scallop and no scallop in the residual stress distribution, and the stress and strain distribution after loadings. First of all, the thermal physical parameters and mechanical properties parameters are correctly defined according to the material of the selected building structures and the relevant norms; and then, before the ANSYS finite element calculation, it is necessary to choose a suitable element type, and mesh the structural model reasonably. The calculation takes advantage of the thermal-structural indirect coupling method. It means that it precedes the thermal analysis firstly, so as to get the temperature distribution of the models, and then re-entering into the Preferences, the thermal mass is changed into the corresponding structural mass. The results of temperature which are gained in the thermal analysis is regarded as the temperature loads born on the structural models, then following calculation proceeding. The main calculating methods are as follow. Firstly, in the thermal analysis, in order to simulate the cooling proceeding of welding lines after welding, with the technology called unit of life and death provided by the ANSYS, the temperature loads of the weld elements in beam-column junction is gradually withdrawn. So it can be found the impact of the angle in the temperature distribution of the different welding composite steel-beam models. And then, the residual stress is calculated in the structural analysis. As a result, the distribution of the residual stress can used to explain the influences of the angle in the welding composite steel-beam. Thirdly, the load calculation is finished on the models with the residual stress that has been calculated in the structural analysis before. So that the impact of the residual stress in the structures, and the impact of the different shapes of the angle in the welding composite steel-beam are foundThrough the thermal analysis and structural analysis about the welding composite steel-beam models with scallop and no scallop by the help of ANSYS software, the conclusions are as follow:(1) The thermal analysis results manifest that the angle alleviates the thermal influences in the welding line of the steel beam. Moreover, the temperature in the steel beam with no scallop is more concentrated;(2) The structural analysis results show that the scallop has a certain impact on the welding residual stress. The stress of non-scallop model has a greater value, because the temperature in the beam-column connection is more difficult in proliferation; The stress of scallop model is not easy to concentrate, because of the existence of corner and the average distribution of the temperature, and of stress is smaller than the values of the non-scallop;(3) After imposed the displacement cycle of repeated load, the scallop structure has the effect in the deformation capacity of beam-column joints, resulting in the deformation capacity of the beam and causing kinds of damages, strain concentration around the scallop area in beam-column junction, the brittle fracture in the flange starting from the scallop, the fracture of the penetration of the welded part and so on;(4) And after imposed the displacement cycle of repeated load on the no scallop model, the beam flange in the area of the free edges, in which the deformation is concentrated, and is difficult to appear the strain mutation phenomenon. The deformability of the nodes has been improved, but the structure is liable to occur brittle fracture.