| The transmission tower belongs to the truss structure and transmits the force through the joints.The force is complicated.The stress of the nodes is very complicated.High tower transmission tower is usually classfieded as steel pipe tower and angle steel tower.Due to the impact of clearance circle,etc.,at the K-joint crank,the angle of steel tower between the branches is less than 30 °."Code for design of steel structure" and "Technical code for the design of tower and pole structures of overhead transmission line" require that the main branch pipe angle of is not more than 30 ° and 15 °.The design of a small angle K-shaped node is not designed accordingly.The relevant research is almost blank.Designers often design conservative stiffeners to ensure safety,resulting in a degree of waste.In the angle steel tower,the commonly used connection forms for K nodes are classfieded as two kinds of arrangement forms according to whether the main material angle into the outer main angle.But there are problems such as machining accuracy and economy.At present,domestic power design institutes often choose the arrangement of joints to design this kind of node according to their own experiences and habits.After the design is completed according to the construction regulations,manual checking is conducted,which lacks the standard uniform design and calculation method.In order to meet the current UHV transmission tower project design and construction needs,this paper studies the mechanical properties and load carrying capacity of typical joints of steel pipe tower and angle steel tower,and mainly does the following work:(1)Through the full-scale test,the force characteristics of the K-joints of the steel tube tower crank arm are studied.The K-joint with the included angle of less than 30 ° between the main tube and the branch tube are studied.The relationship between angle of the main tube and the branch tube,the axial force of the main tube,Stiffener on the bearing capacity of the joint is studied,and the test verifies the provisions of the existing code branch pipe bearing capacity calculation method and the applicability of the method of processing the bearing capacity of the weld.(2)The angle between the main branch of the K-joint and the tapered branch is usually controlled by the clearance circle,and the angle is small.In view of the above,the steel pipe tower K-joint reinforcement is used to control the joint deformation and to improve the stress distribution.In this paper,two kinds of joints layout schemes of axially parallel stiffening plate and transverse ring plate are studied by numerical simulation,and the recommended scheme of K-joints stiffener placement is given and tested.(3)The characteristics of the K-joint of the crank arm of the small-angle steel tubular tower and the calculation method of the local bearing capacity of the ribbed Kjoint are studied.The design proposal formula is given for the K-joint of the crosswelding between the main pipe and the branch pipe whose angle is less than 30°.(4)In this paper,the force characteristics of K-joints in different arrangements of arm are compared and the advantages and disadvantages of each type of arrangement are analyzed.The recommended form is given.In order to compare the force of different joint forms,the finite element analysis of the K-joints was carried out.Singlepackage plug-in connection,single package and double package overhanging connections were used to compare the force characteristics of three different connection forms.Analyze its economy,given the recommended form of such connections. |
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