| Uniaxial tensile tests of the weld from steel structure were carried out in this paper, and the stress strain curves of attachment weld were also set up. On this account, finite element models of attachment weld from hollow section structure’s joint were established, analyzing the influences about different weld models to the K-and T-joint’s ultimate bearing capacity. The main study contents and conclusions are as follows:The tensile tests of butt weld and fillet weld:Contacting uniaxial test with full penetrated butt weld and T-fillet weld whose test specimens were full-scale rods made by Q235 and Q345, determine some basic parameters, such as yield strength, ultimate strength, limiting strain and modulus of elasticity, the typical load-displacement curve. At the mean time, some effects on the material static properties also took into account, such as material type, solder form and the direction of rolling steel.Based on those experiment studies, every test specimen’s constitutive model was set up and corresponding mathematical expressions were set up by polyfit. Then the weld finite element models were validated by comparing to the experiment results and the fracture forms of base material and welding specimen were illustrated at least. The result shows that the weld metal at the left and right sides from the T-fillet weld, welding process made a big difference to its metal strength and almost made no sense to material properties. To the same steel plate, there was significant difference between parallel and perpendicular direction, and almost no difference on strength. Through the reasonable design of specimen size, some typical stress-strain curves were obtained. Numerical simulation was conducted by ANSYS with its element PLANE 42, verifying the feasibility of weld models.The analysis of bearing capacity of steel joints based on different weld simulation:Taking K-joints and T-joints as objects of study and combining with relevant test data to simulate the attachment weld with different elements by ANSYS, the bearing capacity of K-and T-joints were analyzed and the geometric parameter--β、γ、τ on the failure mode and bearing capacity were investigated and explained. The result shows that both solid and shell model can be used to analyze bearing capacity, but shell model is easier than solid model and takes less time for calculating. Therefore, shell elements can be used to conduct large scale calculation with better accuracy. The weld model was set up by adding a circle of shell element, and its thickness was half the chord wall thickness. It can simulate weld better and has better universal property. Without considering weld model, the capacity of joints is lower than experimental result about 20%. If weld model takes into account, the FEM result is lower than experimental result about 13.03%. No mater chooses the shell or solid element, the bearing capacity all has improved and the result of solid element is closer to experiment. Comparing to the traditional numerical simulation with single material property, the bearing capacity will be closer to the reality if weld material property and base material property are considered separately.The bearing capacity of K joints with p and τ increases and with y decreases,the bearing capacity of T joints with p increases and with y decreases,little change with τ.The main creative points of this paper are as follows:Studying constitutive relation of weld material from the connection weld in steel structure joints the first time, prepare the ground of weld simulation and provide with the experimental data for later setting up the damage constitutive property. To the FEM establishment of joints of steel tubular structure, propose that consider the weld material’s and base material’s stress-stain curve separately, and it is closer to reality by using solid element. |
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