The Multi-scale Research For Stress Field Of Transmission Towers Gusset Plate Considering Welding Residual Stress

Transmission project is generally higher than 100 meters, its structure is complex with a large number of bar types, and its joints are connected by welding. If unit characteristic length scale for the 10-3 meter is used to model, the number of element and node, and the workload will be so alarming that make difficult problem arise, resulting in analysis of target is difficult to achieve. However, a simplified model is difficult to meet Project needs. The paper references sub-mode method, using multi-point constraints. Firstly, calculate the overall response of the macro model, cut boundary for the nodes which need further analysis, get the boundary displacement, axial force and bending moment of boundary conditions. Secondly, establish local fine model considering welding residual stress.Finaly, realize multi-scale analysis with calculating the stress of fine model.This paper Simplified the whole transmission tower by 211 force nodes and calculated the mean wind load based on the local conditions and "Load code for the design of building structures", Taking "±500KV DC Large Royal Beach Hanjiang River Crossing Project" which was designed by Central Southern China Electric Power Design Institute as the engineering background. Then, the forward fluctuating wind loads on the 211 nodes of transmission tower was simulated by harmonic superposition method with matlab numerical computing language. Mean wind load and fluctuating wind load was added to the nodes of transmission tower, then got the response and superimposed it. The superposed response was considered as the overall response of the transmission tower under wind load.The residual stress is considered as initial stress when study the impact of welding residual stress on the gusset plate. Based on the ANSYS, We successfully simulate Welding residual stress by an indirect method. This paper analyzes how temperature field in the different time and residual stress of the different directions are and explains the reasons why they are distributed like that. What's more, it is shown that the simulation results are in good accordance with the experiments in the study. The results show that the welding residual maximum stress is close to or above yield strength of steel. There has geometric mutation on the start and end of groove weld where the nodes residual stress is great.Make a small scale analysis on the basis of overall transmission tower solution, obtain the result of gusset plate stress and key nodes stress time-history, and ultimately complete transmission tower gusset plate by multi-scale method. The method proposed in this paper can be a good way to break limitation from sub-model, which is a good supplement on the multi-scale modeling, and it has a good fitness for finite element analysis of large structure containing weld details.