Analysis And Application Research On The Spatial Work Effect Of 500kV Entirely United Framework

As a new form of structural design,entirely united framework has been developing rapidly and widely used in the design of 500kV ehv substation frame structures,with its superiorities in better structural mechanical performance,less construction site demand and lower construction costs.In the entirely united framework with single steel tube columns,the outgoing line columns are connected with the middle frameworks by the busbar beam and incoming line beam,forming a united system.But so far,study on mechanical performance of outgoing line columns which belong to the united system is far from detailed.Meanwhile,the spatial work effect in the united system is simplified by the current design method recommended by code.Thus,with the aim of building the framework to be more scientific and economical in the field of design and application,500kV entirely united framework's spatial work effect in typical load conditions was proposed as the subject in this paper.By using ANSYS,the finite element analysis software,the spatial work performance of united framework system and the spatial work effect coefficients(SWEC)of the outgoing line columns were studied,and the method and suggestion for structural optimization design were proposed.The primary work and achievements are as follows:(1)The single-steel-tube entirely united framework models with three kind of beam-column connection stiffness were established,including rigid joint,pinned joint and semi-rigid joint.The A-type entirely united framework model with semi-rigid joint was established.The corresponding isolated outgoing line column models were established.The analysis method of the semi-rigid connection of beam-column joints based on inflection point was proposed,and the related parameters were suggested.(2)Mechanical and deformation performances of the overall frameworks were analysed,along with that of the outgoing line columns inside or outside the framework system.Factors which affected the analysis result,such as connection stiffness,type of column and load case were discussed.It was revealed that advantages on controlling framework deformation and column deformation were shown in single-steel-tube framework than that in A-type framework;the framework deformations of the two models with semi-rigid connections were not satisfied with the deformation limits,therefore,framework deformations should be controlled in case the semi-rigid connections assumption was adopted;under strong wind load conditions,outgoing line columns were generally used to bear axial force and bending moment,and minor axial force and larger moment of Z axis were shown in single-steel-tube columns than that in A-type columns;the force and moment of single-steel-tube columns with different connection stiffness were close under different wind load conditions,but there was no regularity shown among the results.(3)According to the internal force and displacement analysis results,SWEC of the outgoing line columns for internal force(?_S)and displacement(?_u)were calculated.Comparisons beween?_S and standard value recommend by code were made.It was revealed that the displacement coefficient of the four kinds of framework was less than 1.00;stronger restriction was shown in the single-steel-tube framework system than that in A-type framework,while little difference on displacement coefficient was made by the factor of connection stiffness;under the same load condition,internal force coefficients of single-steel-tube columns were close,and the same performance for magnifying or reducing were shown,while the internal force coefficients of A-type columns were presented as magnifying in most conditions;since certain regularity and uncertainty were shown among the results of internal force coefficients affected by the factors of connection stiffness,type of column and load case,each SWEC was suggested to be applied separately under different working conditions.(4)By the method of applying SWEC,the outgoing line column in the entirely united framework system was simplified into an isolated column model to be studied,which can provid reference for overall structure's mechanical properties and optimal substation design.