| Due to the advantages of transmission capacity and high transmission efficiency,the UHV transmission line is being increasingly widely used and its security cannot be ignored. It is very important to select a correct calculation model in the UHV transmission tower structure nonlinear stress analysis. In traditional design, analysis of tower is simplified to hinge-joint. In fact, the node connection of the UHV transmission tower is a kind of semi-rigid joint between pinned and rigid connection.Generally analysis method is not accorded with the actual mechanical characteristics of the UHV transmission tower structure. Semi-rigid connection steel frame at home and abroad have been carried on thoroughly and made gratifying achievements, but the UHV transmission tower is different from that of the steel frame special space lattice structure. The structure form, the node structure, material selection and mechanical characteristics are different so that those methods are not suitable. It needs special research. Therefore, this article has carried on the research concerning the nonlinear stress analysis on semi-rigid jointed UHV transmission tower structure, and examines the semi-rigid nodes for the influence degree of the mechanical performance under different parameters of engineering design, then provide necessary guidance for practical engineering design.This paper established a typical UHV transmission tower angle-plate K-node finite element entity model,and calculated the moment-rotation curve.After checking with the test result, this node model was taken into the semi-rigid UHV transmission tower plane model,the space tower-leg model and whole tower model for nonlinear stress analysis. Though computing and analysis the UHV transmission tower-leg、the whole tower structure which has a large number of degrees of freedom, this article studied the semi-rigid node’s rotational stiffness(bending stiffness and torsional stiffness) influence with the performance of UHV transmission tower structure systematically, and analysised the regularity about transmission tower with different heights,node bending stiffness,torsional stiffness,load form and initial defects.Basing an these analysis results, the following conclusions were drawed:1)Using ANSYS analysis software to establish the finite element model of angle-plate K-node can effectively reflect the semi-rigid joint stress performance. Through the comparing of the moment-rotation curve’s numerical results with the experimental results, the rationality of the numerical simulation method was verified.2)Analyzing the semi-rigid plane tower-leg model, confirmed that the model can well simulate the mechanical characteristics of the tower-legs, at the same time, proved the UHV lattice Angle of transmission tower joint is a semi-rigid joint between pinned and rigid connection. Since the influence factors of semi-rigid nodes is too many, the analysis of rotational stiffness under the influence of factors such as line stiffness ratio, heights of tower legs, internode number, the angle between the principal and inclined member and initial defects, was made to obtain the scope of the influence of various factors. By fitting a large number of calculated data, the limit bearing capacity calculation formula of plane tower legs is made.3)Based on the analysis of the plane tower-legs,this article further analyzed the semi-rigid tower leg stress resistance performance of the space model, and obtained the influence of the UHV transmission tower rotational stiffness with the ultimate capacity under factors such as material line stiffness ratio, heights of tower legs, loading angle, internode number,the angle between the principal and inclined member and initial defects. The space tower leg ultimate bearing capacity are obtained by amending the formula for computing the ultimate bearing capacity of plane tower leged.4) Based on the calculation and analysis of tower leg structure, the whole semi-rigid UHV transmission tower stress performance were further studied. In different material line stiffness ratio, tower heights, load angle and initial defects, the analysis of joint rotational stiffness of semi-rigid UHV transmission tower impacting on the ultimate capacity was studied, providing reference for practical engineering design and ultimate capacity analysis of UHV transmission tower. Limiting the scope of the various parameters can make the damage occurred in tower tower leg position, thus we can use the space limit bearing capacity formula of tower leg for undertakes checking.5)The influence of semi-rigid nodes on dynamic characteristics of the UHV transmission tower are analyzed. |
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