Study On Stable Bearing Capacity Of X-Braced Truss Structure Of Unequal-Angle Steel In Transmission Tower

With the development of society,the power demand has been a necessity for human life.As the main structures of power transmission industry,transmission towers have become a vital and difficult project at home and abroad.At present,the transmission line towers of equilateral angle steel have been studied deeply by many scholars,while there is little research on the tower of unequal angle steel.This article describes the experimental investigation of the bearing capacity of two types of common transmission tower internodes X-Braced Truss Structure of unequal Angle steel,and the cross member of ultimate bearing capacity,failure pattern and cross internal force in tension and compression ratio of 0.2.The parameters of ABAQUS are further studied in order to research the stable bearing capacity of unequal crossing cross-sections.Firstly,the verification of the FEM based on test data was performed.Secondly,according to the validated finite element full-section models,the equivalent simplification is adopted on an inter-section model utilizing spring stiffness instead of the leg member.Then the finite element analysis of unequal angle steels considering different internal force ratios,different cross-sections,different intersection positions,and different material strengths were investigated.A correction coefficient for calculating the length of unequal-angle steel cross-bracing is proposed on this basis.The following conclusions are drawn from the research of the above content:(1)Two types of common lattice sections were tested to research the bearing capacity and failure model of cross bracing under tension/compression loading.The results show that the unequal angle steels were simultaneously of out-plane and in-plane buckling while the maximum cross section of the X-braced truss structure occurred near the intersection and near the lower end of compression me.(2)An equivalent internode finite element model was established for unequal-angle steel X-braced truss structure.The stability properties were studied,considering different material properties,intersection locations,slanted cross-section specifications,and gusset plate thickness under different internal force ratios.If one member is in tension and the other is in compression,both the stability capacity of cross bracing increases with compression.If the cross members are both in compression,the stability capacity of cross bracing decreases with compression.Under the condition of simultaneous compression,increasing the strength of the material and the position of the intersection point will have little effect on the improvement of the bearing capacity.The X-braced truss structure bearing capacity decreases with the decrease of the thickness of the gusset plate,but this effect is weakened as the steel strength increases.If the out-of-plane limb length increases and the in-plane limb length decreases,with the internal force of the tension brace being greater than 60 percent of that of the compression brace,the bearing capacity decreases..(3)According to the results of the test and the finite element analysis,the calculated length correction factor for unequal-angle steel cross bracings was proposed and compared with the existing codes.